Finite element (FE) coupled thermal-mechanical analysis is widely used to predict the deformation and residualstress of wire arc additive manufacturing (WAAM) parts. In this study, an innovative single-layermulti-bead...Finite element (FE) coupled thermal-mechanical analysis is widely used to predict the deformation and residualstress of wire arc additive manufacturing (WAAM) parts. In this study, an innovative single-layermulti-bead profilegeometric modeling method through the isosceles trapezoid function is proposed to build the FE model of theWAAMprocess. Firstly, a straight-line model for overlapping beads based on the parabola function was establishedto calculate the optimal center distance. Then, the isosceles trapezoid-based profile was employed to replace theparabola profiles of the parabola-based overlapping model to establish an innovative isosceles trapezoid-basedmulti-bead overlapping geometric model. The rationality of the isosceles trapezoid-based overlapping model wasconfirmed by comparing the geometric deviation and the heat dissipation performance index of the two overlappingmodels. In addition, the FE-coupled thermal-mechanical analysis, as well as a comparative experiment of thesingle-layer eight-bead deposition process show that the simulation results of the above two models agree with theexperimental results. At the same time, the proposed isosceles trapezoid-based overlappingmodels are all straightlineprofiles, which can be divided into high-quality FE elements. It can improve the modeling efficiency andshorten the simulation calculation time. The innovative modeling method proposed in this study can provide anefficient and high-precision geometricmodelingmethod forWAAMpart FE coupled thermal-mechanical analysis.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
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
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
基金the National Natural Science Foundation of China(Grant No.51705287)the Scientific Research Foundation of Hubei Provincial Education Department(Grant No.D20211203).
文摘Finite element (FE) coupled thermal-mechanical analysis is widely used to predict the deformation and residualstress of wire arc additive manufacturing (WAAM) parts. In this study, an innovative single-layermulti-bead profilegeometric modeling method through the isosceles trapezoid function is proposed to build the FE model of theWAAMprocess. Firstly, a straight-line model for overlapping beads based on the parabola function was establishedto calculate the optimal center distance. Then, the isosceles trapezoid-based profile was employed to replace theparabola profiles of the parabola-based overlapping model to establish an innovative isosceles trapezoid-basedmulti-bead overlapping geometric model. The rationality of the isosceles trapezoid-based overlapping model wasconfirmed by comparing the geometric deviation and the heat dissipation performance index of the two overlappingmodels. In addition, the FE-coupled thermal-mechanical analysis, as well as a comparative experiment of thesingle-layer eight-bead deposition process show that the simulation results of the above two models agree with theexperimental results. At the same time, the proposed isosceles trapezoid-based overlappingmodels are all straightlineprofiles, which can be divided into high-quality FE elements. It can improve the modeling efficiency andshorten the simulation calculation time. The innovative modeling method proposed in this study can provide anefficient and high-precision geometricmodelingmethod forWAAMpart FE coupled thermal-mechanical analysis.
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 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.
