This work characterizes microstructural evolutions of electron beam melted(EBM) Ti-6 Al-4 V alloy modified via laser shock peening(LSP).The depth stress distribution and tensile properties of EBM Ti-6 Al-4 V alloy wer...This work characterizes microstructural evolutions of electron beam melted(EBM) Ti-6 Al-4 V alloy modified via laser shock peening(LSP).The depth stress distribution and tensile properties of EBM Ti-6 Al-4 V alloy were measured before and after LSP.The results indicate that microstructure consists of β phase with 7.2%±0.4% vol.% and balance α lamellar in EBM sample,and the α lamella was refined into nano-equiaxed grains and submicro-equiaxed grains after LSP.The dominant refinement mechanism is revealed during LSP.Stacking faults were found in the LSP-treated sample,and their corresponding planes were determined as(0001) basal plane,(1010) prismatic plane,and(1011) pyramidal plane obtained by high resolution transmission electron microscopy.The subgrains and high-angle grains formed during dynamic recrystallization were identified by selected area electron diffraction pattern.The LSP treatment produces a significantly residual compressive stress approximately-380 MPa with the depth of compressive stress layer reaching 450 μm.Strength and elongation of the EBM sample were significantly increased after LSP.The strength and ductility enhancements are attributed to compre s sive stress,grain refinement and grain gradient distribution of α phase.展开更多
The effects of laser shock peening (LSP) on the impact wear behavior of Ti-6Al-4V alloys were investigated by a homemade impact wear test rig. The microstructure and mechanical properties of the peened samples were st...The effects of laser shock peening (LSP) on the impact wear behavior of Ti-6Al-4V alloys were investigated by a homemade impact wear test rig. The microstructure and mechanical properties of the peened samples were studied. During the impact wear test, the energy absorption, impact force, wear contact time and wear mechanism of all the test samples were investigated in terms of the influence of the impact kinetic energy. The results showed that microhardness, elastic modulus and residual compressive stress of the treated samples were markedly improved. The wear resistances of both treated samples were highly improved after LSP, and a higher pulse energy corresponded to a more obvious effect. Besides, the wear in all test samples involved a combination of abrasive and oxidation wear and fatigue spalling.展开更多
The fatigue properties of laser shock processing （LSP） on both side surfaces of fastener hole with diameter of 3 mm in the LY12CZ aluminum alloy specimens were investigated. The superficial residual stress was measu...The fatigue properties of laser shock processing （LSP） on both side surfaces of fastener hole with diameter of 3 mm in the LY12CZ aluminum alloy specimens were investigated. The superficial residual stress was measured by X-ray diffraction method. Fatigue experiments of specimens with and without LSP were performed, and the microstructural features of fracture of specimens were characterized by scanning electron microscopy （SEM）. The results indicate that the compressive residual stress can be induced into the surface of specimen, and the fatigue life of the specimen with LSP is 3.5 times as long as that of specimen without LSP. The location of fatigue crack initiation is transferred from the top surface to the sub-surface after LSP, and the fatigue striation spacing of the treated specimen during the expanding fatigue crack is narrower than that of the untreated specimen. Furthermore, the diameters of the dimples on the fatigue crack rupture zone of the specimen with LSP are relatively bigger, which is related to the serious plastic deformation in the material with LSP.展开更多
基金supported financially by the Shanghai Science and Technology Committee Innovation Grant (Nos. 17JC1400600 and 17JC1400603)Distinguished Professor Program of Shanghai University of Engineering Science。
文摘This work characterizes microstructural evolutions of electron beam melted(EBM) Ti-6 Al-4 V alloy modified via laser shock peening(LSP).The depth stress distribution and tensile properties of EBM Ti-6 Al-4 V alloy were measured before and after LSP.The results indicate that microstructure consists of β phase with 7.2%±0.4% vol.% and balance α lamellar in EBM sample,and the α lamella was refined into nano-equiaxed grains and submicro-equiaxed grains after LSP.The dominant refinement mechanism is revealed during LSP.Stacking faults were found in the LSP-treated sample,and their corresponding planes were determined as(0001) basal plane,(1010) prismatic plane,and(1011) pyramidal plane obtained by high resolution transmission electron microscopy.The subgrains and high-angle grains formed during dynamic recrystallization were identified by selected area electron diffraction pattern.The LSP treatment produces a significantly residual compressive stress approximately-380 MPa with the depth of compressive stress layer reaching 450 μm.Strength and elongation of the EBM sample were significantly increased after LSP.The strength and ductility enhancements are attributed to compre s sive stress,grain refinement and grain gradient distribution of α phase.
基金Project(2016YFB1102601)supported by the National Key R&D Program of ChinaProjects(51375407,U1530136)supported by the National Natural Science Foundation of ChinaProject(2017TD0017)supported by the Young Scientific Innovation Team of Science and Technology of Sichuan Province,China
文摘The effects of laser shock peening (LSP) on the impact wear behavior of Ti-6Al-4V alloys were investigated by a homemade impact wear test rig. The microstructure and mechanical properties of the peened samples were studied. During the impact wear test, the energy absorption, impact force, wear contact time and wear mechanism of all the test samples were investigated in terms of the influence of the impact kinetic energy. The results showed that microhardness, elastic modulus and residual compressive stress of the treated samples were markedly improved. The wear resistances of both treated samples were highly improved after LSP, and a higher pulse energy corresponded to a more obvious effect. Besides, the wear in all test samples involved a combination of abrasive and oxidation wear and fatigue spalling.
基金Project (51175002) supported by the National Natural Science Foundation of ChinaProject (090414156) supported by the Natural Science Foundation of Anhui Province,China
文摘The fatigue properties of laser shock processing （LSP） on both side surfaces of fastener hole with diameter of 3 mm in the LY12CZ aluminum alloy specimens were investigated. The superficial residual stress was measured by X-ray diffraction method. Fatigue experiments of specimens with and without LSP were performed, and the microstructural features of fracture of specimens were characterized by scanning electron microscopy （SEM）. The results indicate that the compressive residual stress can be induced into the surface of specimen, and the fatigue life of the specimen with LSP is 3.5 times as long as that of specimen without LSP. The location of fatigue crack initiation is transferred from the top surface to the sub-surface after LSP, and the fatigue striation spacing of the treated specimen during the expanding fatigue crack is narrower than that of the untreated specimen. Furthermore, the diameters of the dimples on the fatigue crack rupture zone of the specimen with LSP are relatively bigger, which is related to the serious plastic deformation in the material with LSP.
