The refinement of the as-cast grain structure in austenitic heat-resistant stainless steel depends on the formation of active solid nuclei during solidification.Titanium(Ti)additions successfully induced the formation...The refinement of the as-cast grain structure in austenitic heat-resistant stainless steel depends on the formation of active solid nuclei during solidification.Titanium(Ti)additions successfully induced the formation of Ti-containing inclusions,enhancing heterogeneous nucleation and promoting equiaxed dendritic growth in 347H stainless steel.Thermal simulation experiments indicated that the equiaxed crystal ratios increased notably with Ti content;samples with 0.06,0.12,and 0.36 wt.%Ti exhibited equiaxed ratios of 18%,24%,and 41%,respectively.Three primary inclusion types—TiN,Al_(2)O_(3)-TiN,and TiO_(x)-TiN—were identified at the cores of equiaxed dendrites,with nucleation core sizes predominantly ranging from 0.5 to 8μm.Among the tested samples,the 0.36 wt.%Ti addition produced the highest nucleation core density.Increasing Ti content significantly elevated dendrite tip undercooling from 2.6 K(0.06 wt.%Ti)to 10.8 K(0.36 wt.%Ti),accelerating solidification front instability and thus enhancing heterogeneous nucleation.Additionally,higher Ti content increased the divergence angle between adjacent columnar dendrites,further promoting the columnar-to-equiaxed transition(CET).展开更多
Micropillar compression tests were used to investigate the influence of hydrogen on the deformation behavior and hydrogen embrittlement(HE)of nitrogen-alloyed austenitic stainless steel QN_(2)109.Results indicate that...Micropillar compression tests were used to investigate the influence of hydrogen on the deformation behavior and hydrogen embrittlement(HE)of nitrogen-alloyed austenitic stainless steel QN_(2)109.Results indicate that the hydrogen increases the dislocation density,reduces the yield stress,and accelerates the formation and intersection of slip bands,with hydrogen-induced cracks initiating at slip band intersections.X-ray diffraction confirms the absence of martensitic transformation,ruling out the role of martensitic transformation in HE.The micropillar compression technique is highly sensitive for characterizing hydrogen-material interactions,owing to the material’s low hydrogen diffusivity and the small size of its hydrogen-affected zone.These findings align with the hydrogen-enhanced localized plasticity mechanism.展开更多
To elucidate the accelerated degradation mechanisms of metallic interconnects in operational solid oxide fuel cells,the oxidation behavior of FSS430 ferritic stainless steel under the coupling of simultaneous electric...To elucidate the accelerated degradation mechanisms of metallic interconnects in operational solid oxide fuel cells,the oxidation behavior of FSS430 ferritic stainless steel under the coupling of simultaneous electrical current and high-temperature exposure is investigated.Isothermal thermogravimetric analysis was employed to quantify oxidation kinetics,complemented by microstructural characterization using X-ray diffraction,scanning electron microscopy with energy-dispersive spectroscopy and transmission electron microscopy.Experimental results demonstrate that the applied current dramatically enhances oxidation rates,increasing specific mass gain from 0.25 mg/cm^(2)(0 A/cm^(2))to 5.20 mg/cm^(2)(0.2 A/cm^(2))and oxide scale thickness from 1.87 to 15.62μm after 200 h.This acceleration originates from current-induced electromigration forces that promote cationic transport through the oxide layer.The quantitative relationships between current density and oxidation parameters are established,enabling predictive modeling of interconnector degradation in solid oxide fuel cell(SOFC)systems.展开更多
Different from previous attention on the austenization temperature or dwelling time of PH13-8Mo stainless steels,the effect of the cooling rate on the hierarchical microstructure and mechanical properties was revealed...Different from previous attention on the austenization temperature or dwelling time of PH13-8Mo stainless steels,the effect of the cooling rate on the hierarchical microstructure and mechanical properties was revealed.For all of water,oil,air and furnace cooling,there is almost-complete martensite with the favorable hardenability.The increase in cooling rate mainly increases the density of dislocation and residual strain in the as-solution annealed matrix.After aging treatment,the cooling rate dominates the ratio of high-angle grain boundaries(HAGBs)instead of the size of martensite blocks.The ratio of HAGBs continuously increases with the decreased cooling rate,while the width of blocks maintains 2.40-2.49μm.Meanwhile,more reversed austenite distributes at the martensite sub-grain boundaries.By comparison,the increased rate of water cooling contributes to a favorable precipitation of NiAl with fine size and dispersive distribution caused by more accumulated internal defects of vacancies and dislocations.With the decrease of cooling rate,NiAl precipitates exhibits a similar diameter of~7 nm while a larger inter-particle distance of~22 nm.In the case of low cooling rate(oil,air and furnace),the stable precipitation strengthening effect contributes to a high yield strength of~1.3 GPa and ultimate tensile strength of~1.4 GPa.The high-ratio HAGBs,reversed austenite and NiAl precipitates with larger-interparticle distance synergistically improve the impact toughness(V-notched Charpy impact energy of 100-110 J).展开更多
Cold deformation treatment of Cu-bearing stainless steel through a cold rolling process combined with electric pulse treatment(EPT)can significantly improve the microstructure and formability of cold-rolled Cu-bearing...Cold deformation treatment of Cu-bearing stainless steel through a cold rolling process combined with electric pulse treatment(EPT)can significantly improve the microstructure and formability of cold-rolled Cu-bearing stainless steel.The microstructure after EPT was characterized by scanning electron microscopy,transmission electron microscopy,and in-situ tensile testing.It is found that compared with conventional heat treatment,EPT process can significantly promote the nucleation rate and mobility at grain boundaries of the deformed samples,greatly accelerating the recovery and static recrystallization of Cu-bearing stainless steel samples at lower temperatures and contributing to the recovery of anisotropy and the re-molding of deformed samples.Microstructural characterization and theoretical analyses show that the rapid recrystallization during EPT process is caused not only by Joule heating effects but also by non-thermal effects that accelerate grain boundary migration and dislocation destruction and regeneration.In addition,EPT process significantly accelerated the nucleation and precipitation growth of Cu-rich phase.The coarsening of Cu-rich phase during EPT process is due to not only the high vacancy diffusion coefficient under the action of the electric pulse but also the increase in the vacancy diffusion flux induced by the electromigration in the process of the electric pulse.展开更多
350 keV He^(+) ions were injected into laser powder bed fusion(LPBF)-processed 304L stainless steel and traditional rolled 304L stainless steel with a flux of 1×10^(17) ions/cm^(2) at room temperature,followed by...350 keV He^(+) ions were injected into laser powder bed fusion(LPBF)-processed 304L stainless steel and traditional rolled 304L stainless steel with a flux of 1×10^(17) ions/cm^(2) at room temperature,followed by annealing at 750℃ for 10,100,and 300 h,respectively.The results showed that material swelling due to helium bubble coarsening was almost not observed in either the LPBF or rolled samples after 10 h of annealing duration.Rapid coarsening and swelling of bubbles occurred in the rolled samples,but only moderate bubble growth occurred in the LPBF sample after annealing for 100 h.After annealing for 300 h,the helium bubbles in both samples tended to grow steadily.For 10 h of annealing,the irradiated samples were in a disequilibrium state,and the apparent activation energy(E^(act))calculated by the Arrhenius model determined that helium atoms tended to diffuse through the displacement mechanism,and helium bubbles grew under the migration and coalescence(MC)mechanism.With annealing times over 100 h,the high-density dislocations and nano-oxide particles in the LPBF sample still had a strong trapping effect on the movement and growth of helium bubbles.After annealing for 300 h,the cellular subgrains in the LPBF sample decomposed,and the nano-oxide particles had no trapping effect on the helium bubbles.At this time,the dislocation structure played a primary role in suppressing the growth of helium bubbles,and the radiation resistance of the LPBF sample remained superior to that of the rolled samples.展开更多
Incorporating ceramic particles into metal matrices is a proven strategy for boosting mechanical properties and wear resistance.The reinforcement potential of tungsten carbide(WC)particles in 316L stainless steel is r...Incorporating ceramic particles into metal matrices is a proven strategy for boosting mechanical properties and wear resistance.The reinforcement potential of tungsten carbide(WC)particles in 316L stainless steel is revealed,utilizing selective laser melting(SLM)to fabricate composites with 5 and 10 vol.%WC.The WC incorporation markedly alters the composite’s microstructure and mechanical attributes.Notably,5 vol.%WC-316L composite exhibits a refined submicron cellular structure,averaging 0.67μm in grain size.Elemental diffusion at WC-316L interface formed a 0.8μm gradient transition layer enriched with M_(2)C carbides(Fe,Cr,W),ensuring robust metallurgical bonding.Compared with unreinforced 316L,5%WC composite exhibits a 70%increase in tensile strength,reaching 1012.6 MPa,and a 25.3%rise in hardness,while maintaining acceptable ductility.10%WC composite achieves a 70.8%hardness enhancement,albeit with reduced elongation.Friction coefficient is reduced by up to 17.3%,and the wear mechanism shifts from adhesive to abrasive,significantly improving wear resistance.展开更多
Titanium plates with a Ti−O solid solution surface-hardened layer were cold roll-bonded with 304 stainless steel plates with high work hardening rates.The evolution and mechanisms affecting the interfacial bonding str...Titanium plates with a Ti−O solid solution surface-hardened layer were cold roll-bonded with 304 stainless steel plates with high work hardening rates.The evolution and mechanisms affecting the interfacial bonding strength in titanium/stainless steel laminated composites were investigated.Results indicate that the hardened layer reduces the interfacial bonding strength from over 261 MPa to less than 204 MPa.During the cold roll-bonding process,the hardened layer fractures,leading to the formation of multi-scale cracks that are difficult for the stainless steel to fill.This not only hinders the development of an interlocking interface but also leads to the presence of numerous microcracks and hardened blocks along the nearly straight interface,consequently weakening the interfacial bonding strength.In metals with high work hardening rates,the conventional approach of enhancing interface interlocking and improving interfacial bonding strength by using a surface-hardened layer becomes less effective.展开更多
Austenitic stainless steels(ASSs)are widely used in various in-dustries such as aerospace,nuclear energy,food,and biotechnol-ogy owing to their exceptional combination of corrosion resistance,weldability,toughness,and...Austenitic stainless steels(ASSs)are widely used in various in-dustries such as aerospace,nuclear energy,food,and biotechnol-ogy owing to their exceptional combination of corrosion resistance,weldability,toughness,and formability[1,2].However,a signifi-cant drawback of ASSs is their low yield strength,which limits their applications in extreme environments[3].Grain boundary(GB)engineering plays a crucial role in enhancing the strength of ASSs[4,5].For instance,grain refinement techniques such as cold rolling followed by annealing[6],severe plastic deformation(SPD)[7],and surface mechanical attrition/rolling treatments[8,9]introduce high-angle GBs(HAGBs)into ASSs,thereby improving their strength.However,the high density of HAGBs limits their ca-pacity for dislocation storage and multiplication,leading to a sig-nificant loss of ductility[10,11].Additionally,several studies have shown that twin boundaries(TBs)can simultaneously enhance the strength,toughness,and corrosion resistance of ASSs[12,13].展开更多
Super duplex stainless steels(SDSSs)and hyper duplex stainless steels(HDSSs),with more alloying elements content,are more corrosion resistant than the standard grades.Progresses of research works on weldability of SDS...Super duplex stainless steels(SDSSs)and hyper duplex stainless steels(HDSSs),with more alloying elements content,are more corrosion resistant than the standard grades.Progresses of research works on weldability of SDSSs and HDSSs in recent years are reviewed in this paper.If proper heat input is provided,SDSSs and HDSSs can be welded with most fusion welding processes,while tungsten inert gas welding is the most popular process.SDSSs and HDSSs are more prone to secondary phases precipitation than the standard and lean grades,and heat input for SDSSs and HDSSs welding is restricted to a smaller range.Matching filler materials are usually recommended for SDSSs and HDSSs welding,rather than Ni-riched ones for standard and lean grades.Nitrogen addition in shielding gas is always beneficial.Post weld heat treatment with slow cooling rate will be harmful.Hot cracking tendency of SDSSs and HDSSs joints is not high,but sometimes they can suffer from hydrogen induced stress cracking.展开更多
In-situ formed high Mn steel coating reinforced by carbides was formed by laser surface alloying(LSA).Laser alloyed layers on 1Cr18Ni9Ti steel with Mn+W_(2)C(specimen A),Mn+NiWC(specimen B)and Mn+SiC(specimen C)powder...In-situ formed high Mn steel coating reinforced by carbides was formed by laser surface alloying(LSA).Laser alloyed layers on 1Cr18Ni9Ti steel with Mn+W_(2)C(specimen A),Mn+NiWC(specimen B)and Mn+SiC(specimen C)powders were fabricated to improve the wear and corrosion behavior of 1Cr18Ni9Ti steel blades in high speed mixers.Microstructure evolution,phases,element distribution,microhardness,wear and corrosion behavior of the laser alloyed layers were investigated.Results indicated that high Mn steel matrix composites with undissolved W_(2)C,WC and other in-situ formed carbides were formed by LSA with Mn+W_(2)C and Mn+NiWC while SiC totally dissolved into the high Mn matrix when adding Mn+SiC.Ni as the binding phase in Ni-WC powder decreased the crack sensitivity of the alloyed layer as compared with the addition of W_(2)C powder.An improvement in average microhardness was achieved in the matrix in specimen A,B and C,with the value of 615,602 and 277 HV_(0.5),while that of the substrate was 212 HV_(0.5).The increase of microhardness,wear and corrosion resistance is highly corelated to microstructure,formed phases,type and content of carbides,micro-hardness and toughness of the alloyed layers.展开更多
In 316L austenitic stainless steel,the presence of ferrite phase severely affects the non-magnetic properties.316L austenitic stainless steel with low-alloy type(L-316L)and high-alloy type(H-316L)has been studied.The ...In 316L austenitic stainless steel,the presence of ferrite phase severely affects the non-magnetic properties.316L austenitic stainless steel with low-alloy type(L-316L)and high-alloy type(H-316L)has been studied.The microstructure and solidification kinetics of the two as-cast grades were in situ observed by high temperature confocal laser scanning microscopy(HT-CLSM).There are significant differences in the as-cast microstructures of the two 316L stainless steel compositions.In L-316L steel,ferrite morphology appears as the short rods with a ferrite content of 6.98%,forming a dual-phase microstructure consisting of austenite and ferrite.Conversely,in H-316L steel,the ferrite appears as discontinuous network structures with a content of 4.41%,forming a microstructure composed of austenite and sigma(σ)phase.The alloying elements in H-316L steel exhibit a complex distribution,with Ni and Mo enriching at the austenite grain boundaries.HT-CLSM experiments provide the real-time observation of the solidification processes of both 316L specimens and reveal distinct solidification modes:L-316L steel solidifies in an FA mode,whereas H-316L steel solidifies in an AF mode.These differences result in ferrite and austenite predominantly serving as the nucleation and growth phases,respectively.The solidification mode observed by experiments is similar to the thermodynamic calculation results.The L-316L steel solidified in the FA mode and showed minimal element segregation,which lead to a direct transformation of ferrite to austenite phase(δ→γ)during phase transformation after solidification.Besides,the H-316L steel solidified in the AF mode and showed severe element segregation,which lead to Mo enrichment at grain boundaries and transformation of ferrite into sigma and austenite phases through the eutectoid reaction(δ→σ+γ).展开更多
The effect of hot band annealing processes—batch annealing and continuous annealing—on the texture evolution and ridging performance of ferritic stainless steel was investigated.The surface and central layers of the...The effect of hot band annealing processes—batch annealing and continuous annealing—on the texture evolution and ridging performance of ferritic stainless steel was investigated.The surface and central layers of the hot band exhibited strong shear and plane deformation textures,respectively.After batch annealing,the texture intensity of the hot-rolled sheet texture significantly decreased,and a weak recrystallization texture appeared,while fully recrystallized grains occurred after continuous annealing.A complete recrystallized{111}texture was obtained after recrystallization annealing.The sheet subjected to continuous annealing exhibited the highest intensity of{111}texture,which was accompanied by a dispersed grain orientation distribution,resulting in the lowest ridging height.展开更多
Selective laser melting(SLM)is a cost-effective 3 D metal additive manufacturing(AM)process.However,AM 316 L stainless steel(SS)has different surface and microstructure properties as compared to conventional ones.Bori...Selective laser melting(SLM)is a cost-effective 3 D metal additive manufacturing(AM)process.However,AM 316 L stainless steel(SS)has different surface and microstructure properties as compared to conventional ones.Boriding process is one of the ways to modify and increase the surface properties.The aim of this study is to predict and understand the growth kinetic of iron boride layers on AM 316 L SS.In this study,the growth kinetic mechanism was evaluated for AM 316 L SS.Pack boriding was applied at 850,900 and 950℃,each for 2,4 and 6 h.The thickness of the boride layers ranged from(1.8±0.3)μm to(27.7±2.2)μm.A diffusion model based on error function solutions in Fick’s second law was proposed to quantitatively predict and elucidate the growth rate of FeB and Fe_(2)B phase layers.The activation energy(Q)values for boron diffusion in FeB layer,Fe_(2)B layer,and dual FeB+Fe_(2)B layer were found to be 256.56,161.61 and 209.014 kJ/mol,respectively,which were higher than the conventional 316 L SS.The findings might provide and open new directions and approaches for applications of additively manufactured steels.展开更多
The addition of vanadium substantially enhances the strength of the high-nitrogen austenitic stainless steel(HNASS),while maintaining excellent ductility and pitting corrosion resistance.The effects of vanadium microa...The addition of vanadium substantially enhances the strength of the high-nitrogen austenitic stainless steel(HNASS),while maintaining excellent ductility and pitting corrosion resistance.The effects of vanadium microalloying on the microstructure,mechanical properties,and pitting resistance of HNASS were systematically analyzed with a focus on the role of VN during the pitting process.The results suggest that vanadium promoted the precipitation of VN,contributing to grain boundary pinning and grain refinement.As vanadium content increased,the number of precipitates rose,and the average grain size decreased.At lower vanadium content(0-0.2 wt.%),the strength of the material was significantly reinforced with increasing vanadium content,while maintaining excellent ductility and pitting resistance.However,when the vanadium content reached 0.3-0.4 wt.%,precipitates demonstrated a substantially increased number and coarsened,accompanied by the formation of numerous dislocations around the precipitates.This brought about further strength reinforcement but a marked decline in ductility and pitting resistance.Additionally,pitting corrosion was initiated at the matrix-VN interface.Compared to the matrix,VN exhibited higher reactivity and preferentially reacted with Cl−ions,provoking dissolution.However,NH4+generated during the dissolution of VN facilitated repassivation of the material,suppressing further pitting propagation.展开更多
The trade-offbetween strength and ductility remains a persistent obstacle in the development of advanced structural materials.In the present study,a novel dual-heterogeneous structure with a bimodal grain distribution...The trade-offbetween strength and ductility remains a persistent obstacle in the development of advanced structural materials.In the present study,a novel dual-heterogeneous structure with a bimodal grain distribution in both ferrite and austenite phases was fabricated via cold rolling and partial recrystallization annealing on solution-treated 2205 duplex stainless steel(DSS).The processed steel exhibited superior mechanical properties,with the yield strength increasing from 586 MPa to 903 MPa,and the ultimate tensile strength from 796 MPa to 1082 MPa,while maintaining a high total elongation of 35.3%.Based on in-situ electron backscatter diffraction(EBSD)and scanning electron microscope(SEM)analyses,the microstructural deformation behavior and strengthening mechanisms of the dual-heterostructured 2205 DSS were elucidated.The outstanding combination of strength and ductility was ascribed to the synergistic effects of grain refinement,dislocation strengthening,and hetero-deformation induced(HDI)strengthening.Moreover,the high ductility in DSS was attributed to the coactivation of cross-slip systems in ferrite{110}and{112}along with the single-slip systems in austenite{111}.These findings provide a new strategy for the design and development of high-strength and ultra-high-strength DSSs.展开更多
Stainless steel parts with complex shape can be fabricated using additive manufacturing,which do not rely on molds and dies.However,coarse dendrites induced by repeated heating of additive manufacturing result in weak...Stainless steel parts with complex shape can be fabricated using additive manufacturing,which do not rely on molds and dies.However,coarse dendrites induced by repeated heating of additive manufacturing result in weak properties,which limits its application.In this study,an in-situ ultrasonic rolling(UR)device was developed to assist the laser directed energy deposition(LDED)process.The microstructural characteristics,as well as the microhardness and wear behavior,were studied for the 316L stainless steel manufactured by in-situ ultrasonic rolling assisted LDED.It is found that austenite,ferrite,and small Si oxides are the main constituents of both the LDED and LDED-UR alloy samples.Under the severe plastic deformation of ultrasonic rolling,the long-branched ferrites by LDED are transformed into the rod-like phases by LDED-UR.Meanwhile,the ferrite is more uniformly distributed in the LDED-UR alloy sample compared with that in LDED alloy sample.Columnar grains with the size of 97.85μm appear in the LDED alloy sample,which is larger than the fully equiaxed grains(22.35μm)of the LDED-UR alloy.The hardness of the LDED-UR alloy sample is about 266.13±13.62 HV_(0.2),which is larger than that of the LDED alloy sample(212.93±12.85 HV_(0.2)).Meanwhile,the wear resistance is also greatly enhanced by applying the assisted in-situ ultrasonic rolling.The achieved high wear resistance can be ascribed to the uniformly distributed hard matter(ferrites)and the impedance of dislocations by high fraction of grain boundaries.Abrasive wear and adhesive wear are identified as the primary wear mechanisms of the studied alloy.Gaining an in-depth understanding of the relationship between wear mechanisms and microstructures offers an effective approach in manufacturing high wear resistant alloys suitable for use in harsh working environments.展开更多
Austenitic stainless steel(ASS)is a common material used in high-pressure hydrogen systems.Prolonged exposure to high-pressure hydrogen can cause hydrogen embrittlement(HE),raising significant safety concerns.Selectiv...Austenitic stainless steel(ASS)is a common material used in high-pressure hydrogen systems.Prolonged exposure to high-pressure hydrogen can cause hydrogen embrittlement(HE),raising significant safety concerns.Selective Laser Melting(SLM),known for its high precision,is a promising additive manufacturing technology that has been widely adopted across various industries.Studies have reported that under certain SLM manufacturing conditions and process parameters,the HE resistance of SLM ASS is significantly better than that of conventionally manufactured(CM)ASS,showing great potential for application in high-pressure hydrogen systems.Thus,studying the HE of SLM ASS is crucial for further improving the safety of high-pressure hydrogen systems.This paper provides an overview of the SLM process,reviews the mechanisms of HE and their synergistic effects,and analyzes the HE characteristics of SLM ASS.Additionally,it examines the influence of unique microstructures and SLM process variables on HE of SLM ASS and offers recommendations for future research to enhance the safety of high-pressure hydrogen systems.展开更多
This study investigates the mechanical properties and microstructure of SS304L stainless steel(SS)fabricated via laser powder bed fusion(LPBF)under controlled oxygen levels(0.2%)at both room and cryogenic temperatures...This study investigates the mechanical properties and microstructure of SS304L stainless steel(SS)fabricated via laser powder bed fusion(LPBF)under controlled oxygen levels(0.2%)at both room and cryogenic temperatures(77 K and 4 K).Experimental results show that the LPBF SS304L exhibits significant improvements in yield strength(YS),with an increase of∼336 MPa at room temperature and up to∼398 MPa at 4 K compared to wrought SS304L.Additionally,the current LPBF SS304L demonstrates an extra∼64 MPa YS strengthening over previous LPBF SS304L data at room temperature.These strength enhancements are primarily attributed to oxide dispersion hardening,promoted by the controlled oxygen level,alongside grain boundary strengthening and dislocation hardening,without significant ductility loss.Furthermore,strain-induced martensitic transformation(SIMT)was absent at room temperature and reduced at cryogenic temperatures compared to wrought SS304L,likely due to high dislocation density and nitrogen-stabilized austenite.A jerk flow observed at 4 K is attributed to adiabatic heating from plastic deformation,consistent with the low thermal conductivity.Finite element simulations reveal a short residence time(0.0137 s)for molten material during the LPBF process,with oxide particles forming predominantly through heterogeneous nucleation at the melt pool surface,and uniformly distributed by Marangoni convection.These findings provide key insights into developing LPBF parameters for enhanced mechanical performance of SS304L for cryogenic and ambient temperature applications.展开更多
Separating oil/water mixtures via superhydrophobic stainless steel mesh(SSM)is a kind of efficient methods of treating oily wastewater,and the superhydrophobic SSM with a low cost,simple fabrication process and robust...Separating oil/water mixtures via superhydrophobic stainless steel mesh(SSM)is a kind of efficient methods of treating oily wastewater,and the superhydrophobic SSM with a low cost,simple fabrication process and robust usability remains a challenge.Herein,urushiol-based benzoxazine(U-D)with a strong substrate adhesion and low surface free energy was used to anchor SiO_(2) particles on the SSM surface to obtain a durable superhydrophobic SSM(PU-D/SiO_(2)/SSM)through a simple dip-coating process,meanwhile,epoxy resin was also introduced to further improve the adhesion between coating and SSM.PU-D/SiO_(2)/SSM could successfully separate various immiscible oil-water mixtures with a separation efficiency of over 96%and a flux up to 27100 L/m^(2) h only by gravity,respectively.Especially,the modified SSM could effectively remove water from water-in-oil emulsion with a separation efficiency of 99.7%.Moreover,PU-D/SiO_(2)/SSM had an outstanding reusability,whose water contact angle and separation efficiency only slightly decreased after 20 cycles of separating oil/water mixture.In addition,the modified SSM also displayed a satisfactory abrasion resistance,chemical stability and self-cleaning property.Thereby,the robust PU-D/SiO_(2)/SSM prepared by cheap raw materials and facile dip-coating method exhibits a high potential for separating oil/water mixtures.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2021YFB3700602)the Jiaxing Key Research and Development Program(Grant No.2022BZ10010).
文摘The refinement of the as-cast grain structure in austenitic heat-resistant stainless steel depends on the formation of active solid nuclei during solidification.Titanium(Ti)additions successfully induced the formation of Ti-containing inclusions,enhancing heterogeneous nucleation and promoting equiaxed dendritic growth in 347H stainless steel.Thermal simulation experiments indicated that the equiaxed crystal ratios increased notably with Ti content;samples with 0.06,0.12,and 0.36 wt.%Ti exhibited equiaxed ratios of 18%,24%,and 41%,respectively.Three primary inclusion types—TiN,Al_(2)O_(3)-TiN,and TiO_(x)-TiN—were identified at the cores of equiaxed dendrites,with nucleation core sizes predominantly ranging from 0.5 to 8μm.Among the tested samples,the 0.36 wt.%Ti addition produced the highest nucleation core density.Increasing Ti content significantly elevated dendrite tip undercooling from 2.6 K(0.06 wt.%Ti)to 10.8 K(0.36 wt.%Ti),accelerating solidification front instability and thus enhancing heterogeneous nucleation.Additionally,higher Ti content increased the divergence angle between adjacent columnar dendrites,further promoting the columnar-to-equiaxed transition(CET).
基金support from the National Natural Science Foundation of China(Grant No.U24A20105 and 52071209)the Major Scientific and Technological Innovation Project of CITIC Group(Grant No.2022ZXKYA06100,with Hongzhou Lu as the principal grant recipient)the Program of Shanghai Academic and Technology Research Leader(Grant No.18XD1402200).
文摘Micropillar compression tests were used to investigate the influence of hydrogen on the deformation behavior and hydrogen embrittlement(HE)of nitrogen-alloyed austenitic stainless steel QN_(2)109.Results indicate that the hydrogen increases the dislocation density,reduces the yield stress,and accelerates the formation and intersection of slip bands,with hydrogen-induced cracks initiating at slip band intersections.X-ray diffraction confirms the absence of martensitic transformation,ruling out the role of martensitic transformation in HE.The micropillar compression technique is highly sensitive for characterizing hydrogen-material interactions,owing to the material’s low hydrogen diffusivity and the small size of its hydrogen-affected zone.These findings align with the hydrogen-enhanced localized plasticity mechanism.
基金supported by Natural Science Foundation of Wuhan(2024040701010051)Natural Science Foundation of Hubei(2023AFB111)and National Natural Science Foundation of China(52401108).
文摘To elucidate the accelerated degradation mechanisms of metallic interconnects in operational solid oxide fuel cells,the oxidation behavior of FSS430 ferritic stainless steel under the coupling of simultaneous electrical current and high-temperature exposure is investigated.Isothermal thermogravimetric analysis was employed to quantify oxidation kinetics,complemented by microstructural characterization using X-ray diffraction,scanning electron microscopy with energy-dispersive spectroscopy and transmission electron microscopy.Experimental results demonstrate that the applied current dramatically enhances oxidation rates,increasing specific mass gain from 0.25 mg/cm^(2)(0 A/cm^(2))to 5.20 mg/cm^(2)(0.2 A/cm^(2))and oxide scale thickness from 1.87 to 15.62μm after 200 h.This acceleration originates from current-induced electromigration forces that promote cationic transport through the oxide layer.The quantitative relationships between current density and oxidation parameters are established,enabling predictive modeling of interconnector degradation in solid oxide fuel cell(SOFC)systems.
基金supported by the National Key Research and Development Program(Grant No.2024YFB3714200)the National Natural Science Foundation of China(Grant Nos.52173305,52233017,52203384,U244120568 and U2441261)+1 种基金the Key Program of the Chinese Academy of Sciences(Grant No.RCJJ-145-24-40)LingChuang Research Project of China National Nuclear Corporation,and Special Funds for Science and Technology Planning of Jiangsu Province(No.BZ2024059).
文摘Different from previous attention on the austenization temperature or dwelling time of PH13-8Mo stainless steels,the effect of the cooling rate on the hierarchical microstructure and mechanical properties was revealed.For all of water,oil,air and furnace cooling,there is almost-complete martensite with the favorable hardenability.The increase in cooling rate mainly increases the density of dislocation and residual strain in the as-solution annealed matrix.After aging treatment,the cooling rate dominates the ratio of high-angle grain boundaries(HAGBs)instead of the size of martensite blocks.The ratio of HAGBs continuously increases with the decreased cooling rate,while the width of blocks maintains 2.40-2.49μm.Meanwhile,more reversed austenite distributes at the martensite sub-grain boundaries.By comparison,the increased rate of water cooling contributes to a favorable precipitation of NiAl with fine size and dispersive distribution caused by more accumulated internal defects of vacancies and dislocations.With the decrease of cooling rate,NiAl precipitates exhibits a similar diameter of~7 nm while a larger inter-particle distance of~22 nm.In the case of low cooling rate(oil,air and furnace),the stable precipitation strengthening effect contributes to a high yield strength of~1.3 GPa and ultimate tensile strength of~1.4 GPa.The high-ratio HAGBs,reversed austenite and NiAl precipitates with larger-interparticle distance synergistically improve the impact toughness(V-notched Charpy impact energy of 100-110 J).
基金supported by the National Natural Science Foundation of China(Nos.52305401 and 52475391)National Key Research and Development Program of China(2024YFB3714301)+1 种基金the Fundamental Research Program of Shanxi Province(202303011211004,TZLH20230818001)Engineering Research Center of the Ministry of Education.
文摘Cold deformation treatment of Cu-bearing stainless steel through a cold rolling process combined with electric pulse treatment(EPT)can significantly improve the microstructure and formability of cold-rolled Cu-bearing stainless steel.The microstructure after EPT was characterized by scanning electron microscopy,transmission electron microscopy,and in-situ tensile testing.It is found that compared with conventional heat treatment,EPT process can significantly promote the nucleation rate and mobility at grain boundaries of the deformed samples,greatly accelerating the recovery and static recrystallization of Cu-bearing stainless steel samples at lower temperatures and contributing to the recovery of anisotropy and the re-molding of deformed samples.Microstructural characterization and theoretical analyses show that the rapid recrystallization during EPT process is caused not only by Joule heating effects but also by non-thermal effects that accelerate grain boundary migration and dislocation destruction and regeneration.In addition,EPT process significantly accelerated the nucleation and precipitation growth of Cu-rich phase.The coarsening of Cu-rich phase during EPT process is due to not only the high vacancy diffusion coefficient under the action of the electric pulse but also the increase in the vacancy diffusion flux induced by the electromigration in the process of the electric pulse.
基金supported by the National Natural Science Foundation of China(Nos.U22B2067 and 52073176).
文摘350 keV He^(+) ions were injected into laser powder bed fusion(LPBF)-processed 304L stainless steel and traditional rolled 304L stainless steel with a flux of 1×10^(17) ions/cm^(2) at room temperature,followed by annealing at 750℃ for 10,100,and 300 h,respectively.The results showed that material swelling due to helium bubble coarsening was almost not observed in either the LPBF or rolled samples after 10 h of annealing duration.Rapid coarsening and swelling of bubbles occurred in the rolled samples,but only moderate bubble growth occurred in the LPBF sample after annealing for 100 h.After annealing for 300 h,the helium bubbles in both samples tended to grow steadily.For 10 h of annealing,the irradiated samples were in a disequilibrium state,and the apparent activation energy(E^(act))calculated by the Arrhenius model determined that helium atoms tended to diffuse through the displacement mechanism,and helium bubbles grew under the migration and coalescence(MC)mechanism.With annealing times over 100 h,the high-density dislocations and nano-oxide particles in the LPBF sample still had a strong trapping effect on the movement and growth of helium bubbles.After annealing for 300 h,the cellular subgrains in the LPBF sample decomposed,and the nano-oxide particles had no trapping effect on the helium bubbles.At this time,the dislocation structure played a primary role in suppressing the growth of helium bubbles,and the radiation resistance of the LPBF sample remained superior to that of the rolled samples.
基金supported by Opening funding of National Key Laboratory of Aerospace Liquid Propulsion(HTKJ2024KL011004)Aeronautical Science Fund of China(ASFC-20240042070001)+2 种基金Opening funding of State Key Laboratory of Metal Forming Technology and Heavy Equipment(B2408100.W05)National Key R&D Program of China(2022YFB4601804)National Natural Science Foundation of China(52250287,52275375).
文摘Incorporating ceramic particles into metal matrices is a proven strategy for boosting mechanical properties and wear resistance.The reinforcement potential of tungsten carbide(WC)particles in 316L stainless steel is revealed,utilizing selective laser melting(SLM)to fabricate composites with 5 and 10 vol.%WC.The WC incorporation markedly alters the composite’s microstructure and mechanical attributes.Notably,5 vol.%WC-316L composite exhibits a refined submicron cellular structure,averaging 0.67μm in grain size.Elemental diffusion at WC-316L interface formed a 0.8μm gradient transition layer enriched with M_(2)C carbides(Fe,Cr,W),ensuring robust metallurgical bonding.Compared with unreinforced 316L,5%WC composite exhibits a 70%increase in tensile strength,reaching 1012.6 MPa,and a 25.3%rise in hardness,while maintaining acceptable ductility.10%WC composite achieves a 70.8%hardness enhancement,albeit with reduced elongation.Friction coefficient is reduced by up to 17.3%,and the wear mechanism shifts from adhesive to abrasive,significantly improving wear resistance.
基金supported by the National Key R&D Program of China (No. 2018YFA0707300)the National Natural Science Foundation of China (No. 52374376)the Introduction Plan for High end Foreign Experts, China (No. G2023105001L)。
文摘Titanium plates with a Ti−O solid solution surface-hardened layer were cold roll-bonded with 304 stainless steel plates with high work hardening rates.The evolution and mechanisms affecting the interfacial bonding strength in titanium/stainless steel laminated composites were investigated.Results indicate that the hardened layer reduces the interfacial bonding strength from over 261 MPa to less than 204 MPa.During the cold roll-bonding process,the hardened layer fractures,leading to the formation of multi-scale cracks that are difficult for the stainless steel to fill.This not only hinders the development of an interlocking interface but also leads to the presence of numerous microcracks and hardened blocks along the nearly straight interface,consequently weakening the interfacial bonding strength.In metals with high work hardening rates,the conventional approach of enhancing interface interlocking and improving interfacial bonding strength by using a surface-hardened layer becomes less effective.
基金financially supported by the National Key R&D program(No.2022YFB3707501)the GDAS’Project of Science and Technology(No.2022GDASZH-2022010202)the Guangdong Provincial Project(Nos.2022A0505050053,2021B1515120071,and 2020B1515130007)。
文摘Austenitic stainless steels(ASSs)are widely used in various in-dustries such as aerospace,nuclear energy,food,and biotechnol-ogy owing to their exceptional combination of corrosion resistance,weldability,toughness,and formability[1,2].However,a signifi-cant drawback of ASSs is their low yield strength,which limits their applications in extreme environments[3].Grain boundary(GB)engineering plays a crucial role in enhancing the strength of ASSs[4,5].For instance,grain refinement techniques such as cold rolling followed by annealing[6],severe plastic deformation(SPD)[7],and surface mechanical attrition/rolling treatments[8,9]introduce high-angle GBs(HAGBs)into ASSs,thereby improving their strength.However,the high density of HAGBs limits their ca-pacity for dislocation storage and multiplication,leading to a sig-nificant loss of ductility[10,11].Additionally,several studies have shown that twin boundaries(TBs)can simultaneously enhance the strength,toughness,and corrosion resistance of ASSs[12,13].
文摘Super duplex stainless steels(SDSSs)and hyper duplex stainless steels(HDSSs),with more alloying elements content,are more corrosion resistant than the standard grades.Progresses of research works on weldability of SDSSs and HDSSs in recent years are reviewed in this paper.If proper heat input is provided,SDSSs and HDSSs can be welded with most fusion welding processes,while tungsten inert gas welding is the most popular process.SDSSs and HDSSs are more prone to secondary phases precipitation than the standard and lean grades,and heat input for SDSSs and HDSSs welding is restricted to a smaller range.Matching filler materials are usually recommended for SDSSs and HDSSs welding,rather than Ni-riched ones for standard and lean grades.Nitrogen addition in shielding gas is always beneficial.Post weld heat treatment with slow cooling rate will be harmful.Hot cracking tendency of SDSSs and HDSSs joints is not high,but sometimes they can suffer from hydrogen induced stress cracking.
文摘In-situ formed high Mn steel coating reinforced by carbides was formed by laser surface alloying(LSA).Laser alloyed layers on 1Cr18Ni9Ti steel with Mn+W_(2)C(specimen A),Mn+NiWC(specimen B)and Mn+SiC(specimen C)powders were fabricated to improve the wear and corrosion behavior of 1Cr18Ni9Ti steel blades in high speed mixers.Microstructure evolution,phases,element distribution,microhardness,wear and corrosion behavior of the laser alloyed layers were investigated.Results indicated that high Mn steel matrix composites with undissolved W_(2)C,WC and other in-situ formed carbides were formed by LSA with Mn+W_(2)C and Mn+NiWC while SiC totally dissolved into the high Mn matrix when adding Mn+SiC.Ni as the binding phase in Ni-WC powder decreased the crack sensitivity of the alloyed layer as compared with the addition of W_(2)C powder.An improvement in average microhardness was achieved in the matrix in specimen A,B and C,with the value of 615,602 and 277 HV_(0.5),while that of the substrate was 212 HV_(0.5).The increase of microhardness,wear and corrosion resistance is highly corelated to microstructure,formed phases,type and content of carbides,micro-hardness and toughness of the alloyed layers.
基金support of the Research Project Supported by Shanxi Scholarship Council of China(2022-040)"Chunhui Plan"Collaborative Research Project by the Ministry of Education of China(HZKY20220507)+2 种基金National Natural Science Foundation of China(52104338)Applied Fundamental Research Programs of Shanxi Province(202303021221036)Shandong Postdoctoral Science Foundation(SDCX-ZG-202303027,SDBX2023054).
文摘In 316L austenitic stainless steel,the presence of ferrite phase severely affects the non-magnetic properties.316L austenitic stainless steel with low-alloy type(L-316L)and high-alloy type(H-316L)has been studied.The microstructure and solidification kinetics of the two as-cast grades were in situ observed by high temperature confocal laser scanning microscopy(HT-CLSM).There are significant differences in the as-cast microstructures of the two 316L stainless steel compositions.In L-316L steel,ferrite morphology appears as the short rods with a ferrite content of 6.98%,forming a dual-phase microstructure consisting of austenite and ferrite.Conversely,in H-316L steel,the ferrite appears as discontinuous network structures with a content of 4.41%,forming a microstructure composed of austenite and sigma(σ)phase.The alloying elements in H-316L steel exhibit a complex distribution,with Ni and Mo enriching at the austenite grain boundaries.HT-CLSM experiments provide the real-time observation of the solidification processes of both 316L specimens and reveal distinct solidification modes:L-316L steel solidifies in an FA mode,whereas H-316L steel solidifies in an AF mode.These differences result in ferrite and austenite predominantly serving as the nucleation and growth phases,respectively.The solidification mode observed by experiments is similar to the thermodynamic calculation results.The L-316L steel solidified in the FA mode and showed minimal element segregation,which lead to a direct transformation of ferrite to austenite phase(δ→γ)during phase transformation after solidification.Besides,the H-316L steel solidified in the AF mode and showed severe element segregation,which lead to Mo enrichment at grain boundaries and transformation of ferrite into sigma and austenite phases through the eutectoid reaction(δ→σ+γ).
文摘The effect of hot band annealing processes—batch annealing and continuous annealing—on the texture evolution and ridging performance of ferritic stainless steel was investigated.The surface and central layers of the hot band exhibited strong shear and plane deformation textures,respectively.After batch annealing,the texture intensity of the hot-rolled sheet texture significantly decreased,and a weak recrystallization texture appeared,while fully recrystallized grains occurred after continuous annealing.A complete recrystallized{111}texture was obtained after recrystallization annealing.The sheet subjected to continuous annealing exhibited the highest intensity of{111}texture,which was accompanied by a dispersed grain orientation distribution,resulting in the lowest ridging height.
文摘Selective laser melting(SLM)is a cost-effective 3 D metal additive manufacturing(AM)process.However,AM 316 L stainless steel(SS)has different surface and microstructure properties as compared to conventional ones.Boriding process is one of the ways to modify and increase the surface properties.The aim of this study is to predict and understand the growth kinetic of iron boride layers on AM 316 L SS.In this study,the growth kinetic mechanism was evaluated for AM 316 L SS.Pack boriding was applied at 850,900 and 950℃,each for 2,4 and 6 h.The thickness of the boride layers ranged from(1.8±0.3)μm to(27.7±2.2)μm.A diffusion model based on error function solutions in Fick’s second law was proposed to quantitatively predict and elucidate the growth rate of FeB and Fe_(2)B phase layers.The activation energy(Q)values for boron diffusion in FeB layer,Fe_(2)B layer,and dual FeB+Fe_(2)B layer were found to be 256.56,161.61 and 209.014 kJ/mol,respectively,which were higher than the conventional 316 L SS.The findings might provide and open new directions and approaches for applications of additively manufactured steels.
基金founded by National Natural Science Foundations of China(Nos.52231003,52201084,and U21A20113)Major Program(JD)of Hubei Province(No.2023BAA019)+1 种基金Natural Science Foundation of Guangdong Province(No.2024A1515011022)Guangdong Province Basic and Applied Basic Research Fund Offshore Wind Power Joint Fund(No.2023B1515250006).
文摘The addition of vanadium substantially enhances the strength of the high-nitrogen austenitic stainless steel(HNASS),while maintaining excellent ductility and pitting corrosion resistance.The effects of vanadium microalloying on the microstructure,mechanical properties,and pitting resistance of HNASS were systematically analyzed with a focus on the role of VN during the pitting process.The results suggest that vanadium promoted the precipitation of VN,contributing to grain boundary pinning and grain refinement.As vanadium content increased,the number of precipitates rose,and the average grain size decreased.At lower vanadium content(0-0.2 wt.%),the strength of the material was significantly reinforced with increasing vanadium content,while maintaining excellent ductility and pitting resistance.However,when the vanadium content reached 0.3-0.4 wt.%,precipitates demonstrated a substantially increased number and coarsened,accompanied by the formation of numerous dislocations around the precipitates.This brought about further strength reinforcement but a marked decline in ductility and pitting resistance.Additionally,pitting corrosion was initiated at the matrix-VN interface.Compared to the matrix,VN exhibited higher reactivity and preferentially reacted with Cl−ions,provoking dissolution.However,NH4+generated during the dissolution of VN facilitated repassivation of the material,suppressing further pitting propagation.
基金supported by the National Natural Science Foundation of China(Nos.U1960115 and U21A20116)the Fundamental Research Funds for the Central Universities(No.N232405-10)Special thanks are due to the instrumental and data analysis from Analytical and Testing Center,Northeastern University.
文摘The trade-offbetween strength and ductility remains a persistent obstacle in the development of advanced structural materials.In the present study,a novel dual-heterogeneous structure with a bimodal grain distribution in both ferrite and austenite phases was fabricated via cold rolling and partial recrystallization annealing on solution-treated 2205 duplex stainless steel(DSS).The processed steel exhibited superior mechanical properties,with the yield strength increasing from 586 MPa to 903 MPa,and the ultimate tensile strength from 796 MPa to 1082 MPa,while maintaining a high total elongation of 35.3%.Based on in-situ electron backscatter diffraction(EBSD)and scanning electron microscope(SEM)analyses,the microstructural deformation behavior and strengthening mechanisms of the dual-heterostructured 2205 DSS were elucidated.The outstanding combination of strength and ductility was ascribed to the synergistic effects of grain refinement,dislocation strengthening,and hetero-deformation induced(HDI)strengthening.Moreover,the high ductility in DSS was attributed to the coactivation of cross-slip systems in ferrite{110}and{112}along with the single-slip systems in austenite{111}.These findings provide a new strategy for the design and development of high-strength and ultra-high-strength DSSs.
基金supports from the National Natural Science Foundation of China(No.52305440)the Natural Science Foundation of Changsha City(Nos.kq2208272,kq2208274)+1 种基金the Tribology Science Fund of the State Key Laboratory of Tribology in Advanced Equipment(No.SKLTKF22B09)the National Key Research and Development Program of China(No.2022YFB3706902)were acknowledged.
文摘Stainless steel parts with complex shape can be fabricated using additive manufacturing,which do not rely on molds and dies.However,coarse dendrites induced by repeated heating of additive manufacturing result in weak properties,which limits its application.In this study,an in-situ ultrasonic rolling(UR)device was developed to assist the laser directed energy deposition(LDED)process.The microstructural characteristics,as well as the microhardness and wear behavior,were studied for the 316L stainless steel manufactured by in-situ ultrasonic rolling assisted LDED.It is found that austenite,ferrite,and small Si oxides are the main constituents of both the LDED and LDED-UR alloy samples.Under the severe plastic deformation of ultrasonic rolling,the long-branched ferrites by LDED are transformed into the rod-like phases by LDED-UR.Meanwhile,the ferrite is more uniformly distributed in the LDED-UR alloy sample compared with that in LDED alloy sample.Columnar grains with the size of 97.85μm appear in the LDED alloy sample,which is larger than the fully equiaxed grains(22.35μm)of the LDED-UR alloy.The hardness of the LDED-UR alloy sample is about 266.13±13.62 HV_(0.2),which is larger than that of the LDED alloy sample(212.93±12.85 HV_(0.2)).Meanwhile,the wear resistance is also greatly enhanced by applying the assisted in-situ ultrasonic rolling.The achieved high wear resistance can be ascribed to the uniformly distributed hard matter(ferrites)and the impedance of dislocations by high fraction of grain boundaries.Abrasive wear and adhesive wear are identified as the primary wear mechanisms of the studied alloy.Gaining an in-depth understanding of the relationship between wear mechanisms and microstructures offers an effective approach in manufacturing high wear resistant alloys suitable for use in harsh working environments.
基金finncially supported by the National Natural Science Foundation of China(No.52075183)the Guangdong Basic and Applied Research Fundamental(No.2023A1515010692)the Key-Area Research and Development Program of Guangdong Province(Nos.2024B1111080002 and 2020B0404020004).
文摘Austenitic stainless steel(ASS)is a common material used in high-pressure hydrogen systems.Prolonged exposure to high-pressure hydrogen can cause hydrogen embrittlement(HE),raising significant safety concerns.Selective Laser Melting(SLM),known for its high precision,is a promising additive manufacturing technology that has been widely adopted across various industries.Studies have reported that under certain SLM manufacturing conditions and process parameters,the HE resistance of SLM ASS is significantly better than that of conventionally manufactured(CM)ASS,showing great potential for application in high-pressure hydrogen systems.Thus,studying the HE of SLM ASS is crucial for further improving the safety of high-pressure hydrogen systems.This paper provides an overview of the SLM process,reviews the mechanisms of HE and their synergistic effects,and analyzes the HE characteristics of SLM ASS.Additionally,it examines the influence of unique microstructures and SLM process variables on HE of SLM ASS and offers recommendations for future research to enhance the safety of high-pressure hydrogen systems.
基金supported financially by Fundamental Research Program of the Korea Institute of Materials Science(No.PNKA320)the Korea Institute of Energy Technology Evaluation and Planning(KETEP)and the Ministry of Trade,Industry&Energy(MOTIE)of the Republic of Korea(RS-2024-00435433).
文摘This study investigates the mechanical properties and microstructure of SS304L stainless steel(SS)fabricated via laser powder bed fusion(LPBF)under controlled oxygen levels(0.2%)at both room and cryogenic temperatures(77 K and 4 K).Experimental results show that the LPBF SS304L exhibits significant improvements in yield strength(YS),with an increase of∼336 MPa at room temperature and up to∼398 MPa at 4 K compared to wrought SS304L.Additionally,the current LPBF SS304L demonstrates an extra∼64 MPa YS strengthening over previous LPBF SS304L data at room temperature.These strength enhancements are primarily attributed to oxide dispersion hardening,promoted by the controlled oxygen level,alongside grain boundary strengthening and dislocation hardening,without significant ductility loss.Furthermore,strain-induced martensitic transformation(SIMT)was absent at room temperature and reduced at cryogenic temperatures compared to wrought SS304L,likely due to high dislocation density and nitrogen-stabilized austenite.A jerk flow observed at 4 K is attributed to adiabatic heating from plastic deformation,consistent with the low thermal conductivity.Finite element simulations reveal a short residence time(0.0137 s)for molten material during the LPBF process,with oxide particles forming predominantly through heterogeneous nucleation at the melt pool surface,and uniformly distributed by Marangoni convection.These findings provide key insights into developing LPBF parameters for enhanced mechanical performance of SS304L for cryogenic and ambient temperature applications.
基金Funded by the National Natural Science Foundation of China(No.22165019)。
文摘Separating oil/water mixtures via superhydrophobic stainless steel mesh(SSM)is a kind of efficient methods of treating oily wastewater,and the superhydrophobic SSM with a low cost,simple fabrication process and robust usability remains a challenge.Herein,urushiol-based benzoxazine(U-D)with a strong substrate adhesion and low surface free energy was used to anchor SiO_(2) particles on the SSM surface to obtain a durable superhydrophobic SSM(PU-D/SiO_(2)/SSM)through a simple dip-coating process,meanwhile,epoxy resin was also introduced to further improve the adhesion between coating and SSM.PU-D/SiO_(2)/SSM could successfully separate various immiscible oil-water mixtures with a separation efficiency of over 96%and a flux up to 27100 L/m^(2) h only by gravity,respectively.Especially,the modified SSM could effectively remove water from water-in-oil emulsion with a separation efficiency of 99.7%.Moreover,PU-D/SiO_(2)/SSM had an outstanding reusability,whose water contact angle and separation efficiency only slightly decreased after 20 cycles of separating oil/water mixture.In addition,the modified SSM also displayed a satisfactory abrasion resistance,chemical stability and self-cleaning property.Thereby,the robust PU-D/SiO_(2)/SSM prepared by cheap raw materials and facile dip-coating method exhibits a high potential for separating oil/water mixtures.
