The Research On Microstructure And Mechanical Properties Of Inconel625 Alloy By Laser Additive Manufacturing

Inconel625 alloy is a kind of Ni-Cr-Mo-Nb alloy.It has good resistance to high temperature oxidation,corrosion resistance and long-term organizational stability,and has been widely used in the aerospace field.Laser additive manufacturing is an extremely rapid dynamic melting and solidification process,the continuous accumulation of heat during the process of layer-by-layer deposition.It is easy to generate large thermal stress and residual stress,resulting in serious elemental segregation and performance anisotropy in the cladding layer.In this paper,Inconel625 alloy deposition samples is fabricated by laser additive manufacturing technology,to study the effect of different heat treatment regimes on the microstructure and mechanical properties of the cladding layer,so as to optimize the organization to improve the mechanical properties.By means of optical microscope,transmission electron microscope,scanning electron microscope and energy dispersive spectrometer,the precipitated phase in the deposited state and heat treatment states was analyzed.The results show that the vertical section of the cladding layer is columnar structure growing along the deposition height direction and is mainly composed of Laves-phase and MC-type carbides;After solution treatment at 980°C/1h,a small amount of needle-like δ phase precipitates near the Laves phase;After solution treatment at 1080°C/1h,the δ phase was completely dissolved,and the main precipitated phases in the structure were Laves phase and MC-type carbide.Tests show that after 980°C/1h solution aging treatment,the average hardness value of the deposited layer is 331 HV,the tensile strength is 908 MPa,and the elongation rate is 36%,which is 18%,12.8%,and 71% higher than that of the original material.Has good comprehensive mechanical properties;After the homogenized solution aging treatment at 1080°C/1h,the material undergoes incomplete recrystallization,the Laves phase dissolves in large amounts,Hardness and room temperature tensile strength have slightly increased,the elongation rate is 90% higher than the original state,and the material has a good shape.