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
Wire-arc directed energy deposition(WA-DED)has emerged as a transformative technology for producing large-scale metal components owing to its capacity for cost-effective fabrication and suitable deposition rates.Recen...Wire-arc directed energy deposition(WA-DED)has emerged as a transformative technology for producing large-scale metal components owing to its capacity for cost-effective fabrication and suitable deposition rates.Recently,the focus has shifted to the WA-DED of magnesium alloys,which are promising lightweight structural materials in the aerospace transportation and military industries.This article systematically reviews recent advancements in magnesium alloys fabricated using WA-DED.It discusses aspects such as forming quality,internal defects,microstructural evolution,and mechanical properties.Prevalent internal defects such as pores and cracks in WA-DED magnesium alloys are identified and characterized.Additionally,strategies for enhancing the manufacturing quality are elucidated.Furthermore,this article comprehensively explores the underlying mechanisms of the interplay among process parameters,internal defects,and microstructural heterogeneity.The main objective is to provide insights into and strategies for defect elimination,microstructural homogenization,and property enhancement.Finally,some perspectives are proposed for further progress in the application of WA-DED magnesium alloy components for superior performance.展开更多
Wire arc-directed energy deposition(WADED)has shown great advantages and potential in fabricating large-scale aluminum(Al)alloy components.However,WADED Al alloys typically exhibit low strength and reliability due to ...Wire arc-directed energy deposition(WADED)has shown great advantages and potential in fabricating large-scale aluminum(Al)alloy components.However,WADED Al alloys typically exhibit low strength and reliability due to pore defects and lack of work hardening or precipitation strengthening.This study utilized a combination of laser shock peening(LSP)and annealing to regulate the microstructure of WADED Al-Mg4.5Mn alloy and enhance mechanical properties.The effects of LSP and annealing on phase composition,pore distribution,and microstructures at multiple scales were systematically investigated to reveal the mechanical property improving mechanism.The results demonstrated that LSP-induced plastic deformation formed a defect-free zone by closing near-surface pore defects.LSP created the hardened layer with gradient mechanical properties by inducing gradient changes in grain size,the number of low-angle grain boundaries(LAGBs),and dislocation density along the depth direction.The annealing process promoted grain coarsening and reduced excessive dislocations and LAGBs,weakening the work harden-ing effect caused by LSP.Furthermore,the high-density dislocations and high stored energy generated by LSP accelerated the recrystallization,facilitating growth of near-surface grains.The defect-free zone,dislocation strengthening,and LAGBs strengthening were responsible for the increase in strength,while the synergistic deformation between hardened layers and soft core facilitated maintaining excellent elon-gation.The strength and elongation of WADED Al alloy can be synergistically improved by balancing the effects of LSP and heat treatment.展开更多
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supported by National Natural Science Foundation of China(Grant Nos.52305331,U20B2031)China Postdoctoral Science Foundation(Grant No.2022M710298)Fundamental Research Funds for the Central Universities,China(Grant No.YWF-22-L-607).
文摘Wire-arc directed energy deposition(WA-DED)has emerged as a transformative technology for producing large-scale metal components owing to its capacity for cost-effective fabrication and suitable deposition rates.Recently,the focus has shifted to the WA-DED of magnesium alloys,which are promising lightweight structural materials in the aerospace transportation and military industries.This article systematically reviews recent advancements in magnesium alloys fabricated using WA-DED.It discusses aspects such as forming quality,internal defects,microstructural evolution,and mechanical properties.Prevalent internal defects such as pores and cracks in WA-DED magnesium alloys are identified and characterized.Additionally,strategies for enhancing the manufacturing quality are elucidated.Furthermore,this article comprehensively explores the underlying mechanisms of the interplay among process parameters,internal defects,and microstructural heterogeneity.The main objective is to provide insights into and strategies for defect elimination,microstructural homogenization,and property enhancement.Finally,some perspectives are proposed for further progress in the application of WA-DED magnesium alloy components for superior performance.
基金supported by the National Key Re-search and Development Program of China(No.2023YFB3407800)the Beijing Natural Science Foundation(No.3202016)the National Natural Science Foundation of China(No.52105315).
文摘Wire arc-directed energy deposition(WADED)has shown great advantages and potential in fabricating large-scale aluminum(Al)alloy components.However,WADED Al alloys typically exhibit low strength and reliability due to pore defects and lack of work hardening or precipitation strengthening.This study utilized a combination of laser shock peening(LSP)and annealing to regulate the microstructure of WADED Al-Mg4.5Mn alloy and enhance mechanical properties.The effects of LSP and annealing on phase composition,pore distribution,and microstructures at multiple scales were systematically investigated to reveal the mechanical property improving mechanism.The results demonstrated that LSP-induced plastic deformation formed a defect-free zone by closing near-surface pore defects.LSP created the hardened layer with gradient mechanical properties by inducing gradient changes in grain size,the number of low-angle grain boundaries(LAGBs),and dislocation density along the depth direction.The annealing process promoted grain coarsening and reduced excessive dislocations and LAGBs,weakening the work harden-ing effect caused by LSP.Furthermore,the high-density dislocations and high stored energy generated by LSP accelerated the recrystallization,facilitating growth of near-surface grains.The defect-free zone,dislocation strengthening,and LAGBs strengthening were responsible for the increase in strength,while the synergistic deformation between hardened layers and soft core facilitated maintaining excellent elon-gation.The strength and elongation of WADED Al alloy can be synergistically improved by balancing the effects of LSP and heat treatment.
