Additive manufacturing(AM)is an emerging customized three-dimensional(3D)functional product fabrication technology.It provides a higher degree of design freedom,reduces manufacturing steps,cost and production cycles.H...Additive manufacturing(AM)is an emerging customized three-dimensional(3D)functional product fabrication technology.It provides a higher degree of design freedom,reduces manufacturing steps,cost and production cycles.However,existing metallic component 3D printing techniques are mainly for the manufacture of single material components.With the increasing commercial applications of AM technologies,the need for 3D printing of more than one type of dissimilar materials in a single component increases.Therefore,investigations on multi-material AM(MMAM)emerge over the past decade.Lasers are currently widely used for the AM of metallic components where high temperatures are involved.Here we report the progress and trend in laser-based macro-and micro-scale AM of multiple metallic components.The methods covered in this paper include laser powder bed fusion,laser powder directed energy deposition,and laser-induced forward transfer for MMAM applications.The principles and process/material characteristics are described.Potential applications and challenges are discussed.Finally,future research directions and prospects are proposed.展开更多
This paper presents the results of a study concerned with the surface hardening of Fe-based alloys and WC-8Co cemented carbide by inte- grating laser cladding and the electrospark deposition processes. Specimens of lo...This paper presents the results of a study concerned with the surface hardening of Fe-based alloys and WC-8Co cemented carbide by inte- grating laser cladding and the electrospark deposition processes. Specimens of low carbon steel were processed firstly by laser cladding with Fe-based alloy powders and then by electrospark deposition with WC-SCo cemented carbide. It is shown that, for these two treatments, the electrospark coating possesses finer microstructure than the laser coating, and the thickness and surface hardness of the electrospark coating can be substantially increased.展开更多
The weld appearance, deposition rate, welding efficiency, stability of arc, laser keyhole characteristic, and weld property were studied by using a novel laser-MIG hybrid welding process with filling wire of aluminum ...The weld appearance, deposition rate, welding efficiency, stability of arc, laser keyhole characteristic, and weld property were studied by using a novel laser-MIG hybrid welding process with filling wire of aluminum alloy. The results were also compared with those by conventional laser-MIG hybrid welding process. It was found that with the suitable process parameters this novel welding process for aluminum alloy was stable and final weld bead had fine appearance. Compared to conventional laser-MIG hybrid welding process, during this novel welding process the stability of arc, the laser keyhole characteristic and the weld property were similar, while the keyhole cycle frequency and keyhole opening area had differences of 1.23% and 15.34%, respectively, and the welding efficiency increased by about 31% without increasing heat input.展开更多
NiTi shape memory alloy(SMA)with nominal composition of Ni 50.8 at%and Ti 49.2 at%was additively manufactured(AM)by selective laser melting(SLM)and laser directed energy deposition(DED)for a comparison study,with emph...NiTi shape memory alloy(SMA)with nominal composition of Ni 50.8 at%and Ti 49.2 at%was additively manufactured(AM)by selective laser melting(SLM)and laser directed energy deposition(DED)for a comparison study,with emphasis on its phase composition,microstructure,mechanical property and deformation mechanism.The results show that the yield strength and ductility obtained by SLM are 100 MPa and 8%,respectively,which are remarkably different from DED result with 700 MPa and 2%.The load path of SLM sample presents shape memory effect,corresponding to martensite phase detected by XRD;while the load path of DED presents pseudo-elasticity with austenite phase.In SLM sample,fine grain and hole provide a uniform deformation during tensile test,resulting in a better elongation.Furthermore,the nonequilibrium solidification was studied by a temperature field simulation to understand the difference of the two 3D printing methods.Both temperature gradient G and growth rate R determine the microstructure and phase in the SLM sample and DED sample,which leads to similar grain morphologies because of similar G/R.While higher G×R of SLM leads to a finer grain size in SLM sample,providing enough driving force for martensite transition and subsequently changing texture compared to DED sample.展开更多
The microstructure evolution and mechanical properties of the as-deposited γ-TiAl-based alloy specimen fabricated via laser melting deposition and as-annealed specimens at different temperatures were investigated.The...The microstructure evolution and mechanical properties of the as-deposited γ-TiAl-based alloy specimen fabricated via laser melting deposition and as-annealed specimens at different temperatures were investigated.The results show that the microstructure of as-deposited specimen is composed of fineα2(Ti3Al)+γlamellae.With the increase of annealing temperature,the bulk γ m(TiAl)phase gradually changes from single γ phase toγphase+acicularα2 phase,finally small γ phase+lamellar α2+γ phase.Compared with the mechanical properties of as-depositedγ-TiAl alloy(tensile strength 469 MPa,elongation 1.1%),after annealing at 1260℃ for 30 min followed by furnace cooling(FC),the room-temperature tensile strength of the specimen is 543.4 MPa and the elongation is 3.7%,which are obviously improved.展开更多
文摘Additive manufacturing(AM)is an emerging customized three-dimensional(3D)functional product fabrication technology.It provides a higher degree of design freedom,reduces manufacturing steps,cost and production cycles.However,existing metallic component 3D printing techniques are mainly for the manufacture of single material components.With the increasing commercial applications of AM technologies,the need for 3D printing of more than one type of dissimilar materials in a single component increases.Therefore,investigations on multi-material AM(MMAM)emerge over the past decade.Lasers are currently widely used for the AM of metallic components where high temperatures are involved.Here we report the progress and trend in laser-based macro-and micro-scale AM of multiple metallic components.The methods covered in this paper include laser powder bed fusion,laser powder directed energy deposition,and laser-induced forward transfer for MMAM applications.The principles and process/material characteristics are described.Potential applications and challenges are discussed.Finally,future research directions and prospects are proposed.
文摘This paper presents the results of a study concerned with the surface hardening of Fe-based alloys and WC-8Co cemented carbide by inte- grating laser cladding and the electrospark deposition processes. Specimens of low carbon steel were processed firstly by laser cladding with Fe-based alloy powders and then by electrospark deposition with WC-SCo cemented carbide. It is shown that, for these two treatments, the electrospark coating possesses finer microstructure than the laser coating, and the thickness and surface hardness of the electrospark coating can be substantially increased.
基金supported by the Key Science and Technology of Jilin Province(Grant No.20140204070GX)
文摘The weld appearance, deposition rate, welding efficiency, stability of arc, laser keyhole characteristic, and weld property were studied by using a novel laser-MIG hybrid welding process with filling wire of aluminum alloy. The results were also compared with those by conventional laser-MIG hybrid welding process. It was found that with the suitable process parameters this novel welding process for aluminum alloy was stable and final weld bead had fine appearance. Compared to conventional laser-MIG hybrid welding process, during this novel welding process the stability of arc, the laser keyhole characteristic and the weld property were similar, while the keyhole cycle frequency and keyhole opening area had differences of 1.23% and 15.34%, respectively, and the welding efficiency increased by about 31% without increasing heat input.
基金Project(2020JJ2046)supported by the Science Fund for Hunan Distinguished Young Scholars,ChinaProject(S2020GXKJGG0416)supported by the Special Project for Hunan Innovative Province Construction,China+1 种基金Project(2018RS3007)supported by the Huxiang Young Talents,ChinaProject(GuikeAB19050002)supported by the Science Project of Guangxi,China。
文摘NiTi shape memory alloy(SMA)with nominal composition of Ni 50.8 at%and Ti 49.2 at%was additively manufactured(AM)by selective laser melting(SLM)and laser directed energy deposition(DED)for a comparison study,with emphasis on its phase composition,microstructure,mechanical property and deformation mechanism.The results show that the yield strength and ductility obtained by SLM are 100 MPa and 8%,respectively,which are remarkably different from DED result with 700 MPa and 2%.The load path of SLM sample presents shape memory effect,corresponding to martensite phase detected by XRD;while the load path of DED presents pseudo-elasticity with austenite phase.In SLM sample,fine grain and hole provide a uniform deformation during tensile test,resulting in a better elongation.Furthermore,the nonequilibrium solidification was studied by a temperature field simulation to understand the difference of the two 3D printing methods.Both temperature gradient G and growth rate R determine the microstructure and phase in the SLM sample and DED sample,which leads to similar grain morphologies because of similar G/R.While higher G×R of SLM leads to a finer grain size in SLM sample,providing enough driving force for martensite transition and subsequently changing texture compared to DED sample.
基金Project(2017YFB1103600)supported by the National Key Research and Development Program of China。
文摘The microstructure evolution and mechanical properties of the as-deposited γ-TiAl-based alloy specimen fabricated via laser melting deposition and as-annealed specimens at different temperatures were investigated.The results show that the microstructure of as-deposited specimen is composed of fineα2(Ti3Al)+γlamellae.With the increase of annealing temperature,the bulk γ m(TiAl)phase gradually changes from single γ phase toγphase+acicularα2 phase,finally small γ phase+lamellar α2+γ phase.Compared with the mechanical properties of as-depositedγ-TiAl alloy(tensile strength 469 MPa,elongation 1.1%),after annealing at 1260℃ for 30 min followed by furnace cooling(FC),the room-temperature tensile strength of the specimen is 543.4 MPa and the elongation is 3.7%,which are obviously improved.
