Interlayer friction stir processing(FSP)has been proved to be an efective method of enhancing the mechanical properties of wire arc-directed energy deposited(WA-DED)samples.However,the original deposition structure wa...Interlayer friction stir processing(FSP)has been proved to be an efective method of enhancing the mechanical properties of wire arc-directed energy deposited(WA-DED)samples.However,the original deposition structure was still retained in the FSP-WA-DED component besides the processed zone(PZ),thus forming a composite structure.Considering the material utilization and practical service process of the deposited component,more attention should be paid on this special composite structure,but the relevant investigation has not been carried out.In this study,an Al–Mg–Sc alloy was prepared by WA-DED with interlayer FSP treatment,and the composite structure was frstly investigated.Almost all of the pores were eliminated under the pressure efect from the tool shoulder.The grains were further refned with an average size of about 1.2μm in the PZ.Though no severe plastic deformation was involved in the retained WA-DED deposition zone,comparable tensile properties with the PZ sample were obtained in the composite structure.Low ultimate tensile strength(UTS)of 289 MPa and elongation of 3.2%were achieved in the WA-DED sample.After interlayer FSP treatment,the UTS and elongation of the PZ samples were signifcantly increased to 443 MPa and 16.3%,while those in the composite structure remained at relatively high levels of 410 MPa and 13.5%,respectively.Meanwhile,a high fatigue strength of 180 and 130 MPa was obtained in the PZ and composite structure samples,which was clearly higher than that of the WA-DED sample(100 MPa).It is concluded that the defects in traditional WA-DED process can be eliminated in the composite structure after interlayer FSP treatment,resulting in enhanced tensile and fatigue properties,which provides an efective method of improving the mechanical properties of the WA-DED sample.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
Friction stir processing(FSP)was employed as a post-printing surface modification technique to enhance surface properties of arc-directed energy deposited 316 L austenitic stainless-steel parts.Corrosion properties an...Friction stir processing(FSP)was employed as a post-printing surface modification technique to enhance surface properties of arc-directed energy deposited 316 L austenitic stainless-steel parts.Corrosion properties and passivity of stir zone and base metal were investigated in 3.5 wt.%NaCl solution.Results reveal a gradual improvement in corrosion protection ability of formed passive film on the alloy's surface over time.Specifically,FSPed region exhibited superior passive behavior and uniform corrosion resistance compared to base metal.This improvement was attributed to a more homogeneous microstructure of stir zone,which hindered micro-galvanic coupling effect.However,it was observed that FSP-treatment did not effectively impede the propagation of pitting corrosion.展开更多
基金supported by the National Natural Science Foundation of China(No.U23A20538)the Fundamental Research Funds for the Universities of Liaoning Province,Shenyang U40 Outstanding Youth Foundation(No.RC230864)+1 种基金the Foundation of CAS Henan Industrial Technology Innovation&Incubation Center(No.2024110)the Natural Science Foundation of Liaoning Province(No.2023-BS-016)。
文摘Interlayer friction stir processing(FSP)has been proved to be an efective method of enhancing the mechanical properties of wire arc-directed energy deposited(WA-DED)samples.However,the original deposition structure was still retained in the FSP-WA-DED component besides the processed zone(PZ),thus forming a composite structure.Considering the material utilization and practical service process of the deposited component,more attention should be paid on this special composite structure,but the relevant investigation has not been carried out.In this study,an Al–Mg–Sc alloy was prepared by WA-DED with interlayer FSP treatment,and the composite structure was frstly investigated.Almost all of the pores were eliminated under the pressure efect from the tool shoulder.The grains were further refned with an average size of about 1.2μm in the PZ.Though no severe plastic deformation was involved in the retained WA-DED deposition zone,comparable tensile properties with the PZ sample were obtained in the composite structure.Low ultimate tensile strength(UTS)of 289 MPa and elongation of 3.2%were achieved in the WA-DED sample.After interlayer FSP treatment,the UTS and elongation of the PZ samples were signifcantly increased to 443 MPa and 16.3%,while those in the composite structure remained at relatively high levels of 410 MPa and 13.5%,respectively.Meanwhile,a high fatigue strength of 180 and 130 MPa was obtained in the PZ and composite structure samples,which was clearly higher than that of the WA-DED sample(100 MPa).It is concluded that the defects in traditional WA-DED process can be eliminated in the composite structure after interlayer FSP treatment,resulting in enhanced tensile and fatigue properties,which provides an efective method of improving the mechanical properties of the WA-DED sample.
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.
基金the support provided by the Natural Sciences and Engineering Research Council of Canada(NSERC)[grant number RGPIN-2017–04368]the Canada Research Chair program[grant number CRC-2019–00017],Ocean Frontier Institute,and Dalhousie University in making this work possiblethe Herff College of Engineering at the University of Memphis for the financial support of the research through the HCOE-FRG program
文摘Friction stir processing(FSP)was employed as a post-printing surface modification technique to enhance surface properties of arc-directed energy deposited 316 L austenitic stainless-steel parts.Corrosion properties and passivity of stir zone and base metal were investigated in 3.5 wt.%NaCl solution.Results reveal a gradual improvement in corrosion protection ability of formed passive film on the alloy's surface over time.Specifically,FSPed region exhibited superior passive behavior and uniform corrosion resistance compared to base metal.This improvement was attributed to a more homogeneous microstructure of stir zone,which hindered micro-galvanic coupling effect.However,it was observed that FSP-treatment did not effectively impede the propagation of pitting corrosion.
