增材修复对激光沉积制造GH738合金热处理及力学影响

Effect of Additive Repair on Heat Treatment and Mechanics of GH738 Alloy Made by Laser Deposition

以GH738合金类零件为研究对象,分析了增材修复对激光沉积制造GH738合金热处理及力学性能的影响,与基体相比,热影响区γ′相尺寸增大显著,其平均尺寸从50 nm增加到110 nm,平均间距增大显著;碳化物含量在热影响区内减少,部分碳化物有分解现象发生,激光沉积修复试样断口微观形貌属于韧性断裂。老化后,沉积柱状树突的结晶粒界膨胀并合并,形成了新的颗粒。时效温度不同时形成的等轴晶晶体的差异较小;修复区经时效处理后开始有γ′相大量析出,γ′相随时效温度升高继续长大,但γ′相含量变化较小。碳化物经时效处理后主要在晶界析出,与沉积状态相比,样品的拉伸强度在时效处理后显著增加,但塑性减小。随着老化温度上升,修补样品的可塑性逐渐降低。粒界碳化物在包络中析出的话,粒界的龟裂沿着粒界碳化物急速膨胀,金属的机械性质显著降低。

This paper takes GH738 alloy parts as the research object,analyzes the effect of additive repair on the heat treatment and mechanical properties of GH738 alloy.Compared with the matrix,the size ofγ’phase in the heat affected zone increases significantly,its average size increases from 50 nm to 110 nm,and the average spacing increases significantly;the carbide content decreases in the heat affected zone,and some carbides decompose,The fracture micro morphology of laser deposition repair sample belongs to ductile fracture.After aging,the grain boundaries of the as deposited dendrites began to expand and merge,and new grains formed at the same time.After aging treatment,there are a lot ofγ′phase precipitated in the repair area,and theγ′phase continues to grow with the increase of aging temperature,but the content ofγ’phase changes little.Compared with the deposited state,the tensile strength of the sample increased significantly after aging heat treatment,but the plasticity decreased;the plasticity of the repaired sample decreased with the increase of the effective temperature at any time.When the carbide on the grain boundary precipitates in the form of coating,the crack on the grain boundary propagates rapidly along the carbide on the grain boundary,and the mechanical properties of metal are seriously reduced.