Wire arc additive manufacturing(WAAM)has emerged as a promising technique for producing large-scale metal components,favoured by high deposition rates,flexibility and low cost.Despite its potential,the complexity of W...Wire arc additive manufacturing(WAAM)has emerged as a promising technique for producing large-scale metal components,favoured by high deposition rates,flexibility and low cost.Despite its potential,the complexity of WAAM processes,which involves intricate thermal dynamics,phase transitions,and metallurgical,mechanical,and chemical interactions,presents considerable challenges in final product qualities.Simulation technologies in WAAM have proven invaluable,providing accurate predictions in key areas such as material properties,defect identification,deposit morphology,and residual stress.These predictions play a critical role in optimising manufacturing strategies for the final product.This paper provides a comprehensive review of the simulation techniques applied in WAAM,tracing developments from 2013 to 2023.Initially,it analyses the current challenges faced by simulation methods in three main areas.Subsequently,the review explores the current modelling approaches and the applications of these simulations.Following this,the paper discusses the present state of WAAM simulation,identifying specific issues inherent to WAAM simulation itself.Finally,through a thorough review of existing literature and related analysis,the paper offers future perspectives on potential advancements in WAAM simulation strategies.展开更多
Wire arc additive manufacturing(WAAM)presents a promising approach for fabricating medium-to-large austenitic stainless steel components,which are essential in industries like aerospace,pressure vessels,and heat excha...Wire arc additive manufacturing(WAAM)presents a promising approach for fabricating medium-to-large austenitic stainless steel components,which are essential in industries like aerospace,pressure vessels,and heat exchangers.This research examines the mi-crostructural characteristics and tensile behaviour of SS308L manufactured via the gas metal arc welding-based WAAM(WAAM 308L)process.Tensile tests were conducted at room temperature(RT,25℃),300℃,and 600℃in as-built conditions.The microstructure con-sists primarily of austenite grains with retainedδ-ferrite phases distributed within the austenitic matrix.The ferrite fraction,in terms of fer-rite number(FN),ranged between 2.30 and 4.80 along the build direction from top to bottom.The ferrite fraction in the middle region is 3.60 FN.Tensile strength was higher in the horizontal oriented samples(WAAM 308L-H),while ductility was higher in the vertical ones.Tensile results show a gradual reduction in strength with increasing test temperature,in which significant dynamic strain aging(DSA)is observed at 600℃.The variation in serration behavior between the vertical and horizontal specimens may be attributed to microstructural differences arising from the build orientation.The yield strength(YS),ultimate tensile strength(UTS),and elongation(EL)of WAAM 308L at 600℃were(240±10)MPa,(442±16)MPa,and(54±2.00)%,respectively,in the horizontal orientation(WAAM 308L-H),and(248±9)MPa,(412±19)MPa,and(75±2.80)%,respectively,in the vertical orientation(WAAM 308L-V).Fracture surfaces revealed a transition from ductile dimple fracture at RT and 300℃to a mixed ductile-brittle failure with intergranular facets at 600℃.The research explores the applicability and constraints of WAAM-produced 308L stainless steel in high-temperature conditions,offering crucial in-sights for its use in thermally resistant structural and industrial components.展开更多
Additive manufacturing(AM)technologies,with their high degree of flexibility,enhance material utilization in the fabrication of large magnesium alloy parts,effectively meeting the demands of complex geometries.However...Additive manufacturing(AM)technologies,with their high degree of flexibility,enhance material utilization in the fabrication of large magnesium alloy parts,effectively meeting the demands of complex geometries.However,research on the corrosion resistance of magnesium alloy components produced via AM is currently limited.This study investigates the microstructural and corrosion characteristics of AZ91D magnesium alloy fabricated by wire arc additive manufacturing(WAAM)compared to its cast counterpart.A large-sized AZ91D bulk part was deposited on an AZ31 base plate using a layer-by-layer stacking approach.The results showed that the WAAM AZ91D was featured by obviously refined grains from 228.92μm of the cast one to 52.92μm on the travel direction-through thickness(TD-TT)and 50.07μm on the normal direction-through thickness(ND-TT).The rapid solidification process of WAAM inhibited the formation of β-Mg_(17)Al_(12) phase while promoting the formation of uniformly distributed network of dislocations,the dispersive precipitation of nano Al_(8)Mn_(5) phase,as well as Zn segregation.WAAM AZ91D demonstrated the occurrence of pitting corrosion and inferior corrosion resistance compared to cast AZ91D,attributed to the micro-galvanic corrosion between the α-Mg matrix and Al_(8)Mn_(5) particles and the increased number of grain boundaries.展开更多
Owing to the lack of matching commercial welding wires,the development of wire arc additive manufacturing(WAAM)for most aluminum alloys is hindered.A wire-powder synchronous arc additive manufacturing(WPAAM)was propos...Owing to the lack of matching commercial welding wires,the development of wire arc additive manufacturing(WAAM)for most aluminum alloys is hindered.A wire-powder synchronous arc additive manufacturing(WPAAM)was proposed to prepare the target Al-Si-Mg aluminum alloy.Based on the synchronous deposition of AlSi_(12) wire and pure Mg powder,the deposition width of the WPAAMed thin-wall was increased by 61% compared with that of WAAMed thin-wall using AlSi_(12) wire,and the machining allowance was reduced by 81%.The added Mg powder benefited to form refined equiaxed grains,and reduced the average grain size of the WPAAMed thin-wall to 47.1μm,showing a decrease of 23.8% relatively to that of the WAAMed thin-wall.Besides,Mg reacted with Si to form Mg_(2)Si strengthening phases.The mechanical properties tests showed that the ultimate tensile strength and elongation of the WPAAMed thin-wall increased up to 174.5 MPa and 4.1%,reaching 92% and 60% those of the WAAMed thin-wall,respectively.展开更多
Si-containing Mg alloys solidified at conventional rates often contain coarse and sharp Mg_(2)Si phases,which can result in inferior material properties.In this study,Mg-6wt.%Si(Mg-6Si)alloy was prepared by wire arc a...Si-containing Mg alloys solidified at conventional rates often contain coarse and sharp Mg_(2)Si phases,which can result in inferior material properties.In this study,Mg-6wt.%Si(Mg-6Si)alloy was prepared by wire arc additive manufacturing(WAAM),employing the gas tungsten arc welding technique with rapid cooling.The microstructures and mechanical properties of the WAAM alloy were investigated and compared with those of the as-cast samples produced using a metal mold.The results indicate that the WAAM Mg-6Si is harder and stronger than the as-cast samples.The microhardness of the WAAM Mg-6Si increases by 36.6% in comparison to that of as-cast Mg-6Si alloy.Furthermore,the average tensile strengths at room temperature and 150℃ increases by 63.4% and 21.3%,respectively.WAAM refines both the Mg_(2)Si phase and the overall grains,resulting in a homogeneous morphology and improved mechanical properties.The granular Mg_(2)Si phase,characterized by fine particles with a diffused distribution,shows a significant increase in concentration.The acicular Mg_(2)Si phase is distributed along the grain boundaries,and its concentration significantly decreases.The average grain size of the Mg_(2)Si phase is about 9.20μm,about 5 times smaller.The refinement and distribution of the granular Mg_(2)Si phase,as well as the reduction in the amount of needle-like Mg_(2)Si particles,are the key factors for improving the mechanical properties of WAAM Mg-6Si alloy.展开更多
A reasonable process plan is an important basis for implementing wire arc additive and subtractive hybrid manufacturing(ASHM),and a new optimization method is proposed.Firstly,the target parts and machining tools are ...A reasonable process plan is an important basis for implementing wire arc additive and subtractive hybrid manufacturing(ASHM),and a new optimization method is proposed.Firstly,the target parts and machining tools are modeled by level set functions.Secondly,the mathematical model of the additive direction optimization problem is established,and an improved particle swarm optimization algorithm is designed to decide the best additive direction.Then,the two-step strategy is used to plan the hybrid manufacturing alternating sequence.The target parts are directly divided into various processing regions;each processing region is optimized based on manufacturability and manufacturing efficiency,and the optimal hybrid manufacturing alternating sequence is obtained by merging some processing regions.Finally,the method is used to outline the process plan of the designed example model and applied to the actual hybrid manufacturing process of the model.The manufacturing result shows that the method can meet the main considerations in hybrid manufacturing.In addition,the degree of automation of process planning is high,and the dependence on manual intervention is low.展开更多
The Mg-Gd-Y-Zn-Zr(GWZ)alloy containing a long-period ordered stacking(LPSO)phase fabricated by Wire arc additive manufacturing(WAAM)shows substantial potential in the aerospace and automotive industries.In this work,M...The Mg-Gd-Y-Zn-Zr(GWZ)alloy containing a long-period ordered stacking(LPSO)phase fabricated by Wire arc additive manufacturing(WAAM)shows substantial potential in the aerospace and automotive industries.In this work,Mg-9Gd-4Y-1Zn-0.4Zr(wt%)single-layer and multilayer components with high-forming-quality were fabricated using WAAM based on cold metal transfer(WAAM-CMT).The deposition parameters were optimized,achieving better deposition morphology and surface quality.The layer-by-layer cyclic microstructure includes remelting zone(RMZ)and non-remelting zone(NRZ),which consisted of α-Mg matrix,blocky LPSO phase,and eutectic phase.The average grain size were 26.8μm in RMZ and 39.3μm in NRZ,and the volume fraction of secondary phases was around 8%,remaining consistent across different layers.The coarse-fine-grain alternating structure generated hetero deformation induced(HDI)strengthening,while at the same time caused the fracture occurring between the NRZ and RMZ due to the weak interlayer bonding.The thermally stabilized blocky LPSO phase played an effective role on inhibiting grain growth during the solid-solution treatment.The specimen achieved highest isotropic mechanical properties after optimized heat treatment with yield strength,ultimate tensile strength,and elongation higher than 220 MPa,370 MPa,and 8.0%,respectively.The GWZ alloys fabricated by WAAM with great isotropic strength-ductility-synergy are promising candidates to replace the conventionally cast counterparts.展开更多
Customized heat treatment is essential for enhancing the mechanical properties of additively manufactured metallic materials,especially for alloys with complex phase constituents and heterogenous microstructure.Howeve...Customized heat treatment is essential for enhancing the mechanical properties of additively manufactured metallic materials,especially for alloys with complex phase constituents and heterogenous microstructure.However,the interrelated evolutions of different microstructure features make it difficult to establish optimal heat treatment processes.Herein,we proposed a method for customized heat treatment process exploration and establishment to overcome this challenge for such kind of alloys,and a wire arc additively manufactured(WAAM)Mg-Gd-Y-Zn-Zr alloy with layered heterostructure was used for feasibility verification.Through this method,the optimal microstructures(fine grain,controllable amount of long period stacking ordered(LPSO)structure and nano-scaleβ'precipitates)and the corresponding customized heat treatment processes(520°C/30 min+200°C/48 h)were obtained to achieve a good combination of a high strength of 364 MPa and a considerable elongation of 6.2%,which surpassed those of other state-of-the-art WAAM-processed Mg alloys.Furthermore,we evidenced that the favorable effect of the undeformed LPSO structures on the mechanical properties was emphasized only when the nano-scaleβ'precipitates were present.It is believed that the findings promote the application of magnesium alloy workpieces and help to establish customized heat treatment processes for additively manufactured materials.展开更多
The preparation of large-scale magnesium(Mg)alloy parts by wire arc additive manufacturing(WAAM)has broad application prospects,including automotive and aerospace industries.The chemical composition of Mg alloy wires ...The preparation of large-scale magnesium(Mg)alloy parts by wire arc additive manufacturing(WAAM)has broad application prospects,including automotive and aerospace industries.The chemical composition of Mg alloy wires plays a critical role in determining mechanical properties of WAAM Mg alloys.However,types of Mg alloy wires for WAAM need to be extended,in order to improve mechanical properties.Therefore,in the present work,a novel ATZM31 Mg alloy wire has been prepared and applied to the cold metal transfer(CMT)-WAAM process.This study focuses on understanding the forming quality,microstructure evolution,and mechanical properties of the ATZM31 alloy thin-wall component fabricated by WAAM.The results show that the Mg alloy thin-wall component possesses satisfactory formability,with minor sidewall roughness.The ATZM31 thin-wall component is mainly composed of columnar dendrites and equiaxed dendrites of the α-Mg phase,with theη-Al8Mn5phase distributes dispersedly at grain boundaries.The area fraction of the η-Al8Mn5phase is estimated to be~0.21%based on the statistical analysis of SEM images.Due to different cooling behaviors,the distribution of grain size along the build direction of the thin-walled component is uneven.The average grain size is~46μm,~74μm and~61μm at the bottom,middle and top of the ATZM31 alloy thin-wall component,respectively.From the substrate to the top of the ATZM31 alloy thin-wall component,the hardness decreases gradually.The ultimate tensile strength along the deposition direction and build direction are~225 MPa and~214 MPa,respectively,without pronounced anisotropy.The ATZM31 alloy thin-wall component fabricated by WAAM exhibits a comparable ultimate tensile strength to forged AZ31 Mg alloys and weaker anisotropy than wrought Mg alloys.展开更多
Under the working environment of high temperature and strong load impact,hot forging die is prone to failure which reduces the service life of die.Using arc additive manufacturing in the die cavity,a gradient material...Under the working environment of high temperature and strong load impact,hot forging die is prone to failure which reduces the service life of die.Using arc additive manufacturing in the die cavity,a gradient material hot forging die with high precision,superior per-formance,and conformal cooling channels is developed.This improves the toughness of the die cavity and reduces the working temperature,thereby forming an isothermal field,which is an effective method to enhance the lifespan of the hot forging die.Three kinds of gradient flux-cored wires are designed for the surface of 5CrNiMo steel,and the microstructure and mechanical properties between gradient interfaces were studied.Based on the spatial curved structure of shaped waterways in the hot forging die cavity,a study was conducted on the strategy of partitioned forming for the manufacturing of the die with shaped waterways.In order to avoid interference with the arc gun,the hot for-ging die is divided into four regions,namely the transition region,upper,middle,and lower region,based on a combination of cavity depth and internal U-shaped and quadrilateral structures.The results show that the developed flux-cored wires have good moldability with straight sides of deposited metal under different process parameters and flat surface without cracks,pores and other defects.Under the same working conditions,the life of hot forging die formed by the gradient materials is more than multiple times that of the single material hot forging die,and the temperature gradient field of the shaped waterway die is 7℃/cm smaller than that of traditional straight waterway.展开更多
NiTiCu thin walls were produced by twin-wire arc additive manufacturing(T-WAAM)using commercial NiTi and Cu wires as the feedstock materials.This approach aims to solve the problems typically associated with large pha...NiTiCu thin walls were produced by twin-wire arc additive manufacturing(T-WAAM)using commercial NiTi and Cu wires as the feedstock materials.This approach aims to solve the problems typically associated with large phase transformation hysteresis in NiTi shape memory alloys.The microstructure,mechanical properties,and phase transformation behavior of the as-deposited NiTiCu alloy were comprehensively examined.The results re-vealed that the as-deposited NiTiCu alloy was well-formed,with its microstructure showed columnar,equiaxed,and needle-like grains,depending on the location within the deposited walls.The microhardness gradually in-creased from the first to the third layer.The Cu content was 20.80 at%,and Cu-based precipitates were formed in the as-deposited NiTiCu.The volume fractions and lattice parameters of the matrix and precipitates in the as-deposited NiTiCu material were analyzed using high-energy synchrotron X-ray diffraction.The martensitic phase was identified as a B19 crystal structure,and the as-deposited NiTiCu underwent a one-step B2-B19 phase transformation.The tensile strength and fracture strain were approximately 232 MPa and 3.72%,respectively.In particular,the addition of Cu narrowed the phase transformation hysteresis of the as-deposited NiTiCu alloy from 24.4 to 7.1◦C compared with conventional binary NiTi alloys.This study expands the potential of T-WAAM in modifying the phase transformation behavior of NiTi-based ternary alloys.展开更多
Wire arc additive manufacturing(WAAM)technique is a promising approach to producing large-scale metal components due to high deposition efficiency and low production cost.However,fundamental research about WAAM-proces...Wire arc additive manufacturing(WAAM)technique is a promising approach to producing large-scale metal components due to high deposition efficiency and low production cost.However,fundamental research about WAAM-processed Al-Mg-Sc-Zr alloy was still fewer.In this study,Al-6.54Mg-0.36Sc-0.11Zr(wt%)components were successfully manufactured by WAAM with an interlayer temperature at 100℃(named IW)and continuous printing(named CP),and the corresponding porosity,microstructure,and mechanical properties of components were studied in detail.The porosity of components as-deposited was relatively low,about 0.385%and 0.116%,respectively.The microstructures of the two components exhibited the same distribution characteristics in XZ and YZ planes:fine equiaxed grains(FEG)at remelted zone+FEG and coarse equiaxed grain(CEG)alternative distribution at middle zone+FEG at the top zone of the molten pool.The average grain size of component IW was about 10.51±6.01μm,and that of component CP significantly increased,to about 11.85±5.86μm.The short-circuit transition mode of cold metal transfer technology and the heterogeneous nucleation effect of primary Al3(Sc,Zr)and Al3(Sc,Zr,Ti)phases together promoted the formation of equiaxed grains and refined the microstructures.After heat treatment at 325℃and 6 h,nano-Al3Sc precipitated with a size of about 15-50 nm.The yield strength(YS)of components IW and CP increased from 171±3 to 261±1 MPa and 168±7 to 240±17 MPa,respectively.Component IW had the highest ultimate tensile strength,about 400±1 MPa.For WAAMprocessed Al-Mg-Sc-Zr alloys,the contribution of the strengthening mechanism to YS was solid solution strengthening>precipitation strengthening>fine grain strengthening>dislocation strengthening.展开更多
Wire arc additive manufacturing(WAAM)technology has been used to fabricate the multi-layer single-pass deposited wall of AZ80M magnesium(Mg)alloy by gas tungsten arc welding.The formability,thermal cycles,microstructu...Wire arc additive manufacturing(WAAM)technology has been used to fabricate the multi-layer single-pass deposited wall of AZ80M magnesium(Mg)alloy by gas tungsten arc welding.The formability,thermal cycles,microstructural evolution and mechanical properties of the WAAM AZ80M Mg alloy were investigated.The results show that there was significant difference in the temperature variation and the geometries between the original several layers and the subsequent deposited layers.Owing to the arc energy input,the interpass temperature rised rapidly and then stabilized at 150℃.As a result,the width of the deposited wall increased and then kept stable.There were obvious differences in the microstructure of the WAAM AZ80M Mg alloy among the top zone,intermediate zone and bottom zone of deposited wall.During the arc deposition process,theβphase of the WAAM AZ80M Mg alloy redissolved due to the cyclic heat accumulation,and then precipitated in the grain boundary.The cyclic heat accumulation also led to weakening of dendrite segregation.From the substrate to the top zone,the hardness of the deposited wall decreased gradually,and the intermediate zone which was the main body of deposited wall had relatively uniform hardness.The tensile properties of the WAAM AZ80M Mg alloy were different between the vertical direction and the horizontal direction.And the maximum ultimate tensile strength of the WAAM AZ80M Mg alloy was 308 MPa which was close to that of the as-extruded AZ80M Mg alloy.展开更多
Additive manufacturing is a very promising manufacturing method widely used in various industries.In this study,for the first time,a new type of combined cable wire(CCW)with multi-element composition has been designed...Additive manufacturing is a very promising manufacturing method widely used in various industries.In this study,for the first time,a new type of combined cable wire(CCW)with multi-element composition has been designed and developed for arc additive manufacturing(AAM)of non-equiatomic Al-Co-Cr-FeNi high-entropy alloy.CCW composed of 7 filaments and 5 elements has the advantages of high deposition efficiency,self-rotation of welding arc and energy saving capability.Thin HEA walls were fabricated under pure argon gas using cold metal transfer technology.Microstructural observations of the developed HEA reveal(i)BCC and FCC phases,(ii)Good bonding between layers and(iii)defect-free microstructure.The developed alloy exhibits high compression strength(~2.8 GPa)coupled with high plastic strain(~42%)values(possess both strength and ductility).It has been identified that by varying the heat input via torch travel speed,the microstructure and mechanical properties of the HEA can be controlled.From this feasibility study,it has been proved that the innovative CCW method can be used to manufacture HEAs with CCW-AAM.Further,the study highlights the advantage of the rapid cooling involved in the CCW-AAM process which gives rise to superior mechanical properties.展开更多
A graded structural material(GSM)with a material transition from TA15 to TC11 was fabricated by wire arc additive manufacturing(WAAM)method.The grain morphology,chemical composition,microstructure and mechanical prope...A graded structural material(GSM)with a material transition from TA15 to TC11 was fabricated by wire arc additive manufacturing(WAAM)method.The grain morphology,chemical composition,microstructure and mechanical properties of the as-deposited GSM were all characterized to investigate their variations along the deposition direction.The results indicate that from TA15 to TC11,the grain size decreases and a transition from columnar grains to equiaxed grains occurs.The content of alloy element alters greatly within a short distance,and the width of the mutation zone is 800μm.Both TA15 and TC11 regions exhibit basketweave microstructure withα-phase andβ-phase.However,during the transition from TA15 to TC11,theα-lath becomes fine,which leads to an increase in microhardness.The tensile test shows that the bonding strength at the interface is higher than the longitudinal strength of TA15,and the lateral elongation at the interface is higher than that of TA15 and TC11.展开更多
To maximize the benefits of wire arc additive manufacturing(WAAM)processes,the effect of post-deposition heat treatment on the microstructure and mechanical properties of WAAM AZ80M magnesium(Mg)alloy was investigated...To maximize the benefits of wire arc additive manufacturing(WAAM)processes,the effect of post-deposition heat treatment on the microstructure and mechanical properties of WAAM AZ80M magnesium(Mg)alloy was investigated.Three different heat treatment procedures(T4,T5 and T6)were performed.According to the results,after T4 heat treatment,the microsegregation of alloying elements was improved with the eutectic structure dissolved.Samples after T5 heat treatment inherited the net-like distribution of secondary phases similar to the as-deposited sample,where the eutectic structure covering the interdendritic regions and theβ-phase precipitated around the eutectic structure.After T6 heat treatment,the tinyβ-phases re-precipitated from the matrix and distributed in inner and outer of the grains.The hardness distribution of the samples went through T4 and T6 heat treatment was more uniform in comparison to that of T5 heat treated samples.The tensile test showed that the T6 heat treatment improved the strength and ductility,and the anisotropy between horizontal and vertical can be eliminated.Moreover,T4 treated samples exhibited highest ductility.展开更多
Aluminum–Lithium(Al–Li) alloy is a topic of great interest owing to its high strength and light weight, but there are only a few applications of Al–Li alloy in wire ss, a special AA2050 Al–Li alloy + arc additive ...Aluminum–Lithium(Al–Li) alloy is a topic of great interest owing to its high strength and light weight, but there are only a few applications of Al–Li alloy in wire ss, a special AA2050 Al–Li alloy + arc additive manufacturing(WAAM) process. To identify its feasibility in WAAM procewire was produced and employed in the production of straight-walled components, using a WAAM system based on variable polarity gas tungsten arc welding(VP-GTAW) process. The influence of post-deposited heat treatment on the microstructure and property of the deposit was investigated using optical micrographs(OM), scanning electron microscopy(SEM), X-ray diffraction(XRD), hardness and tensile properties tests. Results revealed that the microstructures of AA2050 aluminum deposits varied with their location layers. The upper layers consisted of fine equiaxed grains, while the bottom layer exhibited a coarse columnar structure. Mechanical properties witnessed a significant improvement after post-deposited heat treatment, with the average micro-hardness reaching 141 HV and the ultimate tensile strength exceeding 400 MPa. Fracture morphology exhibited a typical ductile fracture.展开更多
Additive manufacturing(AM)of Mg alloys has become a promising strategy for producing complex structures,but the corrosion performance of AM Mg components remains unexploited.In this study,wire and arc additive manufac...Additive manufacturing(AM)of Mg alloys has become a promising strategy for producing complex structures,but the corrosion performance of AM Mg components remains unexploited.In this study,wire and arc additive manufacturing(WAAM)was employed to produce single AZ31 layer.The results revealed that the WAAM AZ31 was characterized by significant grain refinement with non-textured crystallographic orientation,similar phase composition and stabilized corrosion performance comparing to the cast AZ31.These varied corrosion behaviors were principally ascribed to the size of grain,where cast AZ31 and WAAM AZ31 were featured by micro galvanic corrosion and intergranular corrosion,respectively.展开更多
A high-building multi-directional pipe joint(HBMDPJ)was fabricated by wire and arc additive manufacturing using high-strength low-alloy(HSLA)steel.The microstructure characteristics and transformation were observed an...A high-building multi-directional pipe joint(HBMDPJ)was fabricated by wire and arc additive manufacturing using high-strength low-alloy(HSLA)steel.The microstructure characteristics and transformation were observed and analyzed.The results show that the forming part includes four regions.The solidification zone solidifies as typical columnar crystals from a molten pool.The complete austenitizing zone forms from the solidification zone heated to a temperature greater than 1100℃,and the typical columnar crystals in this zone are difficult to observe.The partial austenitizing zone forms from the completely austenite zone heated between Ac1(austenite transition temperature)and1100℃,which is mainly equiaxed grains.After several thermal cycles,the partial austenitizing zone transforms to the tempering zone,which consistes of fully equiaxed grains.From the solidification zone to the tempering zone,the average grain size decreases from 75 to20μm.The mechanical properties of HBMDPJ satisfies the requirement for the intended application.展开更多
Aluminum alloy is the most widely used light alloy at present.By combining different types of aluminum alloys,their functional properties can be expanded.In the present research,two components composed of 2319(Al-6.5C...Aluminum alloy is the most widely used light alloy at present.By combining different types of aluminum alloys,their functional properties can be expanded.In the present research,two components composed of 2319(Al-6.5Cu)and 5B06(Al-6.4Mg)dissimilar alloys were fabricated by wire and arc additive manufacturing(WAAM).The deposited component with the bottom half of 2319 and the top half of 5B06 exhibits better mechanical properties than its counterpart deposited vice versa.Its ultimate tensile strength,yield strength,and elongation are 258.5 MPa,139.3 MPa,and 5.6%,respectively,which are only slightly inferior to the mechanical properties of 2319 base metal.The results show that for both components,fracture occurred at a layer thickness above the interface layer during the tensile test,regardless of the deposition order.It appears that the thermal stress due to the long dwell time and the remelting of the S-AlCu Mg phase are the main factors promoting crack initiation.Depending on the deposition order,cracks propagate either along the aggregated pores or stripθ-AlCu phase distributed along the grain boundary.By analyzing the heat input and selecting the appropriate depositing order,the strength of WAAM dissimilar aluminum alloys can be effectively improved through the proper control of microstructure and internal defects.展开更多
基金supported in part by China Scholarship Council under Grant 202208200010。
文摘Wire arc additive manufacturing(WAAM)has emerged as a promising technique for producing large-scale metal components,favoured by high deposition rates,flexibility and low cost.Despite its potential,the complexity of WAAM processes,which involves intricate thermal dynamics,phase transitions,and metallurgical,mechanical,and chemical interactions,presents considerable challenges in final product qualities.Simulation technologies in WAAM have proven invaluable,providing accurate predictions in key areas such as material properties,defect identification,deposit morphology,and residual stress.These predictions play a critical role in optimising manufacturing strategies for the final product.This paper provides a comprehensive review of the simulation techniques applied in WAAM,tracing developments from 2013 to 2023.Initially,it analyses the current challenges faced by simulation methods in three main areas.Subsequently,the review explores the current modelling approaches and the applications of these simulations.Following this,the paper discusses the present state of WAAM simulation,identifying specific issues inherent to WAAM simulation itself.Finally,through a thorough review of existing literature and related analysis,the paper offers future perspectives on potential advancements in WAAM simulation strategies.
基金supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP)and the Ministry of Trade,Industry&Energy(MOTIE)of the Republic of Korea program(No.RS-2025-02603127,Innovation Research Center for Zero-carbon Fuel Gas Turbine Design,Manufacture,and Safety).
文摘Wire arc additive manufacturing(WAAM)presents a promising approach for fabricating medium-to-large austenitic stainless steel components,which are essential in industries like aerospace,pressure vessels,and heat exchangers.This research examines the mi-crostructural characteristics and tensile behaviour of SS308L manufactured via the gas metal arc welding-based WAAM(WAAM 308L)process.Tensile tests were conducted at room temperature(RT,25℃),300℃,and 600℃in as-built conditions.The microstructure con-sists primarily of austenite grains with retainedδ-ferrite phases distributed within the austenitic matrix.The ferrite fraction,in terms of fer-rite number(FN),ranged between 2.30 and 4.80 along the build direction from top to bottom.The ferrite fraction in the middle region is 3.60 FN.Tensile strength was higher in the horizontal oriented samples(WAAM 308L-H),while ductility was higher in the vertical ones.Tensile results show a gradual reduction in strength with increasing test temperature,in which significant dynamic strain aging(DSA)is observed at 600℃.The variation in serration behavior between the vertical and horizontal specimens may be attributed to microstructural differences arising from the build orientation.The yield strength(YS),ultimate tensile strength(UTS),and elongation(EL)of WAAM 308L at 600℃were(240±10)MPa,(442±16)MPa,and(54±2.00)%,respectively,in the horizontal orientation(WAAM 308L-H),and(248±9)MPa,(412±19)MPa,and(75±2.80)%,respectively,in the vertical orientation(WAAM 308L-V).Fracture surfaces revealed a transition from ductile dimple fracture at RT and 300℃to a mixed ductile-brittle failure with intergranular facets at 600℃.The research explores the applicability and constraints of WAAM-produced 308L stainless steel in high-temperature conditions,offering crucial in-sights for its use in thermally resistant structural and industrial components.
基金The National Natural Science Foundations of China(Nos.52071191 and 52471080)are acknowledged for providing the financial support.
文摘Additive manufacturing(AM)technologies,with their high degree of flexibility,enhance material utilization in the fabrication of large magnesium alloy parts,effectively meeting the demands of complex geometries.However,research on the corrosion resistance of magnesium alloy components produced via AM is currently limited.This study investigates the microstructural and corrosion characteristics of AZ91D magnesium alloy fabricated by wire arc additive manufacturing(WAAM)compared to its cast counterpart.A large-sized AZ91D bulk part was deposited on an AZ31 base plate using a layer-by-layer stacking approach.The results showed that the WAAM AZ91D was featured by obviously refined grains from 228.92μm of the cast one to 52.92μm on the travel direction-through thickness(TD-TT)and 50.07μm on the normal direction-through thickness(ND-TT).The rapid solidification process of WAAM inhibited the formation of β-Mg_(17)Al_(12) phase while promoting the formation of uniformly distributed network of dislocations,the dispersive precipitation of nano Al_(8)Mn_(5) phase,as well as Zn segregation.WAAM AZ91D demonstrated the occurrence of pitting corrosion and inferior corrosion resistance compared to cast AZ91D,attributed to the micro-galvanic corrosion between the α-Mg matrix and Al_(8)Mn_(5) particles and the increased number of grain boundaries.
基金supported by the National Natural Science Foundation of China(No.52205360)。
文摘Owing to the lack of matching commercial welding wires,the development of wire arc additive manufacturing(WAAM)for most aluminum alloys is hindered.A wire-powder synchronous arc additive manufacturing(WPAAM)was proposed to prepare the target Al-Si-Mg aluminum alloy.Based on the synchronous deposition of AlSi_(12) wire and pure Mg powder,the deposition width of the WPAAMed thin-wall was increased by 61% compared with that of WAAMed thin-wall using AlSi_(12) wire,and the machining allowance was reduced by 81%.The added Mg powder benefited to form refined equiaxed grains,and reduced the average grain size of the WPAAMed thin-wall to 47.1μm,showing a decrease of 23.8% relatively to that of the WAAMed thin-wall.Besides,Mg reacted with Si to form Mg_(2)Si strengthening phases.The mechanical properties tests showed that the ultimate tensile strength and elongation of the WPAAMed thin-wall increased up to 174.5 MPa and 4.1%,reaching 92% and 60% those of the WAAMed thin-wall,respectively.
基金supported by the National Natural Science Foundation of China(Grant Nos.52001037,U2037601,and U21A2048)the Science and Technology Program of Guangzhou,China(Grant No.2022BLC003).
文摘Si-containing Mg alloys solidified at conventional rates often contain coarse and sharp Mg_(2)Si phases,which can result in inferior material properties.In this study,Mg-6wt.%Si(Mg-6Si)alloy was prepared by wire arc additive manufacturing(WAAM),employing the gas tungsten arc welding technique with rapid cooling.The microstructures and mechanical properties of the WAAM alloy were investigated and compared with those of the as-cast samples produced using a metal mold.The results indicate that the WAAM Mg-6Si is harder and stronger than the as-cast samples.The microhardness of the WAAM Mg-6Si increases by 36.6% in comparison to that of as-cast Mg-6Si alloy.Furthermore,the average tensile strengths at room temperature and 150℃ increases by 63.4% and 21.3%,respectively.WAAM refines both the Mg_(2)Si phase and the overall grains,resulting in a homogeneous morphology and improved mechanical properties.The granular Mg_(2)Si phase,characterized by fine particles with a diffused distribution,shows a significant increase in concentration.The acicular Mg_(2)Si phase is distributed along the grain boundaries,and its concentration significantly decreases.The average grain size of the Mg_(2)Si phase is about 9.20μm,about 5 times smaller.The refinement and distribution of the granular Mg_(2)Si phase,as well as the reduction in the amount of needle-like Mg_(2)Si particles,are the key factors for improving the mechanical properties of WAAM Mg-6Si alloy.
基金The National Natural Science Foundation of China(No.52305381)the Natural Science Foundation of Jiangsu Province(No.BK20210351)the Fundamental Research Funds for the Central Universities(No.30923011008).
文摘A reasonable process plan is an important basis for implementing wire arc additive and subtractive hybrid manufacturing(ASHM),and a new optimization method is proposed.Firstly,the target parts and machining tools are modeled by level set functions.Secondly,the mathematical model of the additive direction optimization problem is established,and an improved particle swarm optimization algorithm is designed to decide the best additive direction.Then,the two-step strategy is used to plan the hybrid manufacturing alternating sequence.The target parts are directly divided into various processing regions;each processing region is optimized based on manufacturability and manufacturing efficiency,and the optimal hybrid manufacturing alternating sequence is obtained by merging some processing regions.Finally,the method is used to outline the process plan of the designed example model and applied to the actual hybrid manufacturing process of the model.The manufacturing result shows that the method can meet the main considerations in hybrid manufacturing.In addition,the degree of automation of process planning is high,and the dependence on manual intervention is low.
基金supported by the National Key Research and Development Program of China(No.2021YFB3701004)National Natural Science Foundation of China(No.52071211)Joint Research Center of Advanced Aerospace Technology of Shanghai Academy of Spaceflight Technology-Shanghai Jiao Tong University(No.USCAST2020-1).
文摘The Mg-Gd-Y-Zn-Zr(GWZ)alloy containing a long-period ordered stacking(LPSO)phase fabricated by Wire arc additive manufacturing(WAAM)shows substantial potential in the aerospace and automotive industries.In this work,Mg-9Gd-4Y-1Zn-0.4Zr(wt%)single-layer and multilayer components with high-forming-quality were fabricated using WAAM based on cold metal transfer(WAAM-CMT).The deposition parameters were optimized,achieving better deposition morphology and surface quality.The layer-by-layer cyclic microstructure includes remelting zone(RMZ)and non-remelting zone(NRZ),which consisted of α-Mg matrix,blocky LPSO phase,and eutectic phase.The average grain size were 26.8μm in RMZ and 39.3μm in NRZ,and the volume fraction of secondary phases was around 8%,remaining consistent across different layers.The coarse-fine-grain alternating structure generated hetero deformation induced(HDI)strengthening,while at the same time caused the fracture occurring between the NRZ and RMZ due to the weak interlayer bonding.The thermally stabilized blocky LPSO phase played an effective role on inhibiting grain growth during the solid-solution treatment.The specimen achieved highest isotropic mechanical properties after optimized heat treatment with yield strength,ultimate tensile strength,and elongation higher than 220 MPa,370 MPa,and 8.0%,respectively.The GWZ alloys fabricated by WAAM with great isotropic strength-ductility-synergy are promising candidates to replace the conventionally cast counterparts.
基金supported by the Projects of Major Scientific and Technological Achievements Local Transformation of Xi’an(2022JH-ZDZH-0039)International Science and Technology Cooperation Program of Shaanxi Province (2023-GHZD-50)+9 种基金Project of Qin Chuangyuan ‘Scientist+Engineer’team constructionKey R&D plan of Shaanxi Province (S2023-YF-QCYK-0001-237)Projects of Major Scientific and Technological Achievements Local Transformation of Xi’an (2022JH-ZDZH-0039)National Natural Science Foundation of China (52101134)Natural Science Foundation of Guangdong Province (2022A1515010275)Scientific Research Program Funded by Shaanxi Provincial Education Department (22JK0479)Doctoral Dissertations Innovation Fund of Xi’an University of Technology (101-252072305)Research Start-up Project of Xi’an University of Technology(101-256082204)Natural Science Foundation of Shaanxi Province (2023-JC-QN-0573)Natural Science Basic Research Program of Shaanxi(2023-JC-YB-412)
文摘Customized heat treatment is essential for enhancing the mechanical properties of additively manufactured metallic materials,especially for alloys with complex phase constituents and heterogenous microstructure.However,the interrelated evolutions of different microstructure features make it difficult to establish optimal heat treatment processes.Herein,we proposed a method for customized heat treatment process exploration and establishment to overcome this challenge for such kind of alloys,and a wire arc additively manufactured(WAAM)Mg-Gd-Y-Zn-Zr alloy with layered heterostructure was used for feasibility verification.Through this method,the optimal microstructures(fine grain,controllable amount of long period stacking ordered(LPSO)structure and nano-scaleβ'precipitates)and the corresponding customized heat treatment processes(520°C/30 min+200°C/48 h)were obtained to achieve a good combination of a high strength of 364 MPa and a considerable elongation of 6.2%,which surpassed those of other state-of-the-art WAAM-processed Mg alloys.Furthermore,we evidenced that the favorable effect of the undeformed LPSO structures on the mechanical properties was emphasized only when the nano-scaleβ'precipitates were present.It is believed that the findings promote the application of magnesium alloy workpieces and help to establish customized heat treatment processes for additively manufactured materials.
基金funded by National Natural Science Foundation of China(Nos.52001133 and 52271103)Jilin Scientific and Technological Development Program(Nos.20220301026GX,20210201115GX and 20210301041GX)。
文摘The preparation of large-scale magnesium(Mg)alloy parts by wire arc additive manufacturing(WAAM)has broad application prospects,including automotive and aerospace industries.The chemical composition of Mg alloy wires plays a critical role in determining mechanical properties of WAAM Mg alloys.However,types of Mg alloy wires for WAAM need to be extended,in order to improve mechanical properties.Therefore,in the present work,a novel ATZM31 Mg alloy wire has been prepared and applied to the cold metal transfer(CMT)-WAAM process.This study focuses on understanding the forming quality,microstructure evolution,and mechanical properties of the ATZM31 alloy thin-wall component fabricated by WAAM.The results show that the Mg alloy thin-wall component possesses satisfactory formability,with minor sidewall roughness.The ATZM31 thin-wall component is mainly composed of columnar dendrites and equiaxed dendrites of the α-Mg phase,with theη-Al8Mn5phase distributes dispersedly at grain boundaries.The area fraction of the η-Al8Mn5phase is estimated to be~0.21%based on the statistical analysis of SEM images.Due to different cooling behaviors,the distribution of grain size along the build direction of the thin-walled component is uneven.The average grain size is~46μm,~74μm and~61μm at the bottom,middle and top of the ATZM31 alloy thin-wall component,respectively.From the substrate to the top of the ATZM31 alloy thin-wall component,the hardness decreases gradually.The ultimate tensile strength along the deposition direction and build direction are~225 MPa and~214 MPa,respectively,without pronounced anisotropy.The ATZM31 alloy thin-wall component fabricated by WAAM exhibits a comparable ultimate tensile strength to forged AZ31 Mg alloys and weaker anisotropy than wrought Mg alloys.
基金supported by the National Key R&D Program of China(No.2017YFB1103200).
文摘Under the working environment of high temperature and strong load impact,hot forging die is prone to failure which reduces the service life of die.Using arc additive manufacturing in the die cavity,a gradient material hot forging die with high precision,superior per-formance,and conformal cooling channels is developed.This improves the toughness of the die cavity and reduces the working temperature,thereby forming an isothermal field,which is an effective method to enhance the lifespan of the hot forging die.Three kinds of gradient flux-cored wires are designed for the surface of 5CrNiMo steel,and the microstructure and mechanical properties between gradient interfaces were studied.Based on the spatial curved structure of shaped waterways in the hot forging die cavity,a study was conducted on the strategy of partitioned forming for the manufacturing of the die with shaped waterways.In order to avoid interference with the arc gun,the hot for-ging die is divided into four regions,namely the transition region,upper,middle,and lower region,based on a combination of cavity depth and internal U-shaped and quadrilateral structures.The results show that the developed flux-cored wires have good moldability with straight sides of deposited metal under different process parameters and flat surface without cracks,pores and other defects.Under the same working conditions,the life of hot forging die formed by the gradient materials is more than multiple times that of the single material hot forging die,and the temperature gradient field of the shaped waterway die is 7℃/cm smaller than that of traditional straight waterway.
基金supported by National Natural Science Founda-tion of China(Grant No.52175292)Science and Technology Project of Sichuan Province(Grant Nos.23NSFJQ0064,2022YFQ0058)+2 种基金Guangdong Basic and Applied Basic Research Foundation(Grant No.2021B1515140048)JPO and JS acknowledge the funding by na-tional funds from Fundação para a Ciência e a Tecnologia(FCT),I.P.,within the scope of projects LA/P/0037/2020,UIDP/50025/2020,and UIDB/50025/2020 of the Associate Laboratory Institute of Nanostruc-tures,Nanomodelling,and Nanofabrication-i3NDESY(Hamburg,Germany),a member of the Helmholtz Associa-tion HGF,for providing the experimental facilities.Part of this study was conducted at PETRA III.The research leading to this result was sup-ported by project CALIPSOplus under Grant Agreement 730872 from the EU Framework Programme for Research and Innovation HORIZON 2020.
文摘NiTiCu thin walls were produced by twin-wire arc additive manufacturing(T-WAAM)using commercial NiTi and Cu wires as the feedstock materials.This approach aims to solve the problems typically associated with large phase transformation hysteresis in NiTi shape memory alloys.The microstructure,mechanical properties,and phase transformation behavior of the as-deposited NiTiCu alloy were comprehensively examined.The results re-vealed that the as-deposited NiTiCu alloy was well-formed,with its microstructure showed columnar,equiaxed,and needle-like grains,depending on the location within the deposited walls.The microhardness gradually in-creased from the first to the third layer.The Cu content was 20.80 at%,and Cu-based precipitates were formed in the as-deposited NiTiCu.The volume fractions and lattice parameters of the matrix and precipitates in the as-deposited NiTiCu material were analyzed using high-energy synchrotron X-ray diffraction.The martensitic phase was identified as a B19 crystal structure,and the as-deposited NiTiCu underwent a one-step B2-B19 phase transformation.The tensile strength and fracture strain were approximately 232 MPa and 3.72%,respectively.In particular,the addition of Cu narrowed the phase transformation hysteresis of the as-deposited NiTiCu alloy from 24.4 to 7.1◦C compared with conventional binary NiTi alloys.This study expands the potential of T-WAAM in modifying the phase transformation behavior of NiTi-based ternary alloys.
基金supported by the Basic Key Research Program of Basic Strengthening Plan(No.2021-JCJQ-ZD-075-11)the CISRI Independent Research and Development Programs(Nos.21H62580Z and No.23H60450Z)the National Natural Science Foundation of China(Grant No.52374365).
文摘Wire arc additive manufacturing(WAAM)technique is a promising approach to producing large-scale metal components due to high deposition efficiency and low production cost.However,fundamental research about WAAM-processed Al-Mg-Sc-Zr alloy was still fewer.In this study,Al-6.54Mg-0.36Sc-0.11Zr(wt%)components were successfully manufactured by WAAM with an interlayer temperature at 100℃(named IW)and continuous printing(named CP),and the corresponding porosity,microstructure,and mechanical properties of components were studied in detail.The porosity of components as-deposited was relatively low,about 0.385%and 0.116%,respectively.The microstructures of the two components exhibited the same distribution characteristics in XZ and YZ planes:fine equiaxed grains(FEG)at remelted zone+FEG and coarse equiaxed grain(CEG)alternative distribution at middle zone+FEG at the top zone of the molten pool.The average grain size of component IW was about 10.51±6.01μm,and that of component CP significantly increased,to about 11.85±5.86μm.The short-circuit transition mode of cold metal transfer technology and the heterogeneous nucleation effect of primary Al3(Sc,Zr)and Al3(Sc,Zr,Ti)phases together promoted the formation of equiaxed grains and refined the microstructures.After heat treatment at 325℃and 6 h,nano-Al3Sc precipitated with a size of about 15-50 nm.The yield strength(YS)of components IW and CP increased from 171±3 to 261±1 MPa and 168±7 to 240±17 MPa,respectively.Component IW had the highest ultimate tensile strength,about 400±1 MPa.For WAAMprocessed Al-Mg-Sc-Zr alloys,the contribution of the strengthening mechanism to YS was solid solution strengthening>precipitation strengthening>fine grain strengthening>dislocation strengthening.
基金This work was supported by the China Scholarship Coun-cil(No.201907000039)the national key research and devel-opment plan of China(grant number 2017YFB0305905)the Doctoral Innovation Fund Program of Southwest Jiaotong University(No.D-CX201830).
文摘Wire arc additive manufacturing(WAAM)technology has been used to fabricate the multi-layer single-pass deposited wall of AZ80M magnesium(Mg)alloy by gas tungsten arc welding.The formability,thermal cycles,microstructural evolution and mechanical properties of the WAAM AZ80M Mg alloy were investigated.The results show that there was significant difference in the temperature variation and the geometries between the original several layers and the subsequent deposited layers.Owing to the arc energy input,the interpass temperature rised rapidly and then stabilized at 150℃.As a result,the width of the deposited wall increased and then kept stable.There were obvious differences in the microstructure of the WAAM AZ80M Mg alloy among the top zone,intermediate zone and bottom zone of deposited wall.During the arc deposition process,theβphase of the WAAM AZ80M Mg alloy redissolved due to the cyclic heat accumulation,and then precipitated in the grain boundary.The cyclic heat accumulation also led to weakening of dendrite segregation.From the substrate to the top zone,the hardness of the deposited wall decreased gradually,and the intermediate zone which was the main body of deposited wall had relatively uniform hardness.The tensile properties of the WAAM AZ80M Mg alloy were different between the vertical direction and the horizontal direction.And the maximum ultimate tensile strength of the WAAM AZ80M Mg alloy was 308 MPa which was close to that of the as-extruded AZ80M Mg alloy.
基金the National Natural Science Foundation of China(No.51975419)。
文摘Additive manufacturing is a very promising manufacturing method widely used in various industries.In this study,for the first time,a new type of combined cable wire(CCW)with multi-element composition has been designed and developed for arc additive manufacturing(AAM)of non-equiatomic Al-Co-Cr-FeNi high-entropy alloy.CCW composed of 7 filaments and 5 elements has the advantages of high deposition efficiency,self-rotation of welding arc and energy saving capability.Thin HEA walls were fabricated under pure argon gas using cold metal transfer technology.Microstructural observations of the developed HEA reveal(i)BCC and FCC phases,(ii)Good bonding between layers and(iii)defect-free microstructure.The developed alloy exhibits high compression strength(~2.8 GPa)coupled with high plastic strain(~42%)values(possess both strength and ductility).It has been identified that by varying the heat input via torch travel speed,the microstructure and mechanical properties of the HEA can be controlled.From this feasibility study,it has been proved that the innovative CCW method can be used to manufacture HEAs with CCW-AAM.Further,the study highlights the advantage of the rapid cooling involved in the CCW-AAM process which gives rise to superior mechanical properties.
基金financial supports from the National Natural Science Foundation of China(Nos.51875041,51875042)。
文摘A graded structural material(GSM)with a material transition from TA15 to TC11 was fabricated by wire arc additive manufacturing(WAAM)method.The grain morphology,chemical composition,microstructure and mechanical properties of the as-deposited GSM were all characterized to investigate their variations along the deposition direction.The results indicate that from TA15 to TC11,the grain size decreases and a transition from columnar grains to equiaxed grains occurs.The content of alloy element alters greatly within a short distance,and the width of the mutation zone is 800μm.Both TA15 and TC11 regions exhibit basketweave microstructure withα-phase andβ-phase.However,during the transition from TA15 to TC11,theα-lath becomes fine,which leads to an increase in microhardness.The tensile test shows that the bonding strength at the interface is higher than the longitudinal strength of TA15,and the lateral elongation at the interface is higher than that of TA15 and TC11.
基金the China Scholarship Council[grant numbers:201907000039],the National Key Research and Development Plan of China[grant number 2017YFB0305905]The authors acknowledge the financial support from the 2020 open projects[grant numbers:KLATM202003]of Key laboratory of Advanced Technologies of Materials,Ministry of Education China,Southwest Jiaotong University。
文摘To maximize the benefits of wire arc additive manufacturing(WAAM)processes,the effect of post-deposition heat treatment on the microstructure and mechanical properties of WAAM AZ80M magnesium(Mg)alloy was investigated.Three different heat treatment procedures(T4,T5 and T6)were performed.According to the results,after T4 heat treatment,the microsegregation of alloying elements was improved with the eutectic structure dissolved.Samples after T5 heat treatment inherited the net-like distribution of secondary phases similar to the as-deposited sample,where the eutectic structure covering the interdendritic regions and theβ-phase precipitated around the eutectic structure.After T6 heat treatment,the tinyβ-phases re-precipitated from the matrix and distributed in inner and outer of the grains.The hardness distribution of the samples went through T4 and T6 heat treatment was more uniform in comparison to that of T5 heat treated samples.The tensile test showed that the T6 heat treatment improved the strength and ductility,and the anisotropy between horizontal and vertical can be eliminated.Moreover,T4 treated samples exhibited highest ductility.
基金Supported by National Natural Science Foundation of China(Grant No.51675031)Beijing Municipal Science and Technology Commission and Fundamental Research Funds for the Central Universities(Grant No.YWF-18-BJ-J-244,YWF-19-BJ-J-232)+1 种基金Beijing Natural Science Foundation(Grant No.3182020)the Academic Excellence Foundation of BUAA for PhD
文摘Aluminum–Lithium(Al–Li) alloy is a topic of great interest owing to its high strength and light weight, but there are only a few applications of Al–Li alloy in wire ss, a special AA2050 Al–Li alloy + arc additive manufacturing(WAAM) process. To identify its feasibility in WAAM procewire was produced and employed in the production of straight-walled components, using a WAAM system based on variable polarity gas tungsten arc welding(VP-GTAW) process. The influence of post-deposited heat treatment on the microstructure and property of the deposit was investigated using optical micrographs(OM), scanning electron microscopy(SEM), X-ray diffraction(XRD), hardness and tensile properties tests. Results revealed that the microstructures of AA2050 aluminum deposits varied with their location layers. The upper layers consisted of fine equiaxed grains, while the bottom layer exhibited a coarse columnar structure. Mechanical properties witnessed a significant improvement after post-deposited heat treatment, with the average micro-hardness reaching 141 HV and the ultimate tensile strength exceeding 400 MPa. Fracture morphology exhibited a typical ductile fracture.
基金the financial support by National Key Research and Development Project(Grand No.2020YFC1107202)Guangdong Basic and Applied Basic Research Foundation(Grand No.2020A1515110754)+3 种基金MOE Key Lab of Disaster Forest and Control in Engineering,Jinan University(Grand No.20200904008)Educational Commission of Guangdong Province(Grand No.2020KTSCX012)the Fundamental Research Funds for Central Universities(Grand No.21620342)the support from National Natural Science Foundation of China,NSFC(Grand No.51775556)。
文摘Additive manufacturing(AM)of Mg alloys has become a promising strategy for producing complex structures,but the corrosion performance of AM Mg components remains unexploited.In this study,wire and arc additive manufacturing(WAAM)was employed to produce single AZ31 layer.The results revealed that the WAAM AZ31 was characterized by significant grain refinement with non-textured crystallographic orientation,similar phase composition and stabilized corrosion performance comparing to the cast AZ31.These varied corrosion behaviors were principally ascribed to the size of grain,where cast AZ31 and WAAM AZ31 were featured by micro galvanic corrosion and intergranular corrosion,respectively.
基金financially supported by the National Key R&D Program of China(No.2017YFB1103200)the Independent Innovation Research Fund Project of Huazhong University of Science and Technology(No.2018KFYXMPT002)。
文摘A high-building multi-directional pipe joint(HBMDPJ)was fabricated by wire and arc additive manufacturing using high-strength low-alloy(HSLA)steel.The microstructure characteristics and transformation were observed and analyzed.The results show that the forming part includes four regions.The solidification zone solidifies as typical columnar crystals from a molten pool.The complete austenitizing zone forms from the solidification zone heated to a temperature greater than 1100℃,and the typical columnar crystals in this zone are difficult to observe.The partial austenitizing zone forms from the completely austenite zone heated between Ac1(austenite transition temperature)and1100℃,which is mainly equiaxed grains.After several thermal cycles,the partial austenitizing zone transforms to the tempering zone,which consistes of fully equiaxed grains.From the solidification zone to the tempering zone,the average grain size decreases from 75 to20μm.The mechanical properties of HBMDPJ satisfies the requirement for the intended application.
基金the National Natural Science Foundation of China(No.51805415)the China Postdoctoral Science Foundation(No.2019M663682)the Open Fund of the State Key Laboratory for Mechanical Behavior of Materials(No.20212311)。
文摘Aluminum alloy is the most widely used light alloy at present.By combining different types of aluminum alloys,their functional properties can be expanded.In the present research,two components composed of 2319(Al-6.5Cu)and 5B06(Al-6.4Mg)dissimilar alloys were fabricated by wire and arc additive manufacturing(WAAM).The deposited component with the bottom half of 2319 and the top half of 5B06 exhibits better mechanical properties than its counterpart deposited vice versa.Its ultimate tensile strength,yield strength,and elongation are 258.5 MPa,139.3 MPa,and 5.6%,respectively,which are only slightly inferior to the mechanical properties of 2319 base metal.The results show that for both components,fracture occurred at a layer thickness above the interface layer during the tensile test,regardless of the deposition order.It appears that the thermal stress due to the long dwell time and the remelting of the S-AlCu Mg phase are the main factors promoting crack initiation.Depending on the deposition order,cracks propagate either along the aggregated pores or stripθ-AlCu phase distributed along the grain boundary.By analyzing the heat input and selecting the appropriate depositing order,the strength of WAAM dissimilar aluminum alloys can be effectively improved through the proper control of microstructure and internal defects.
