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在Ar气和空气环境中激光立体成形了Inconel 718镍基高温合金坯.显微组织观察、拉伸性能和高周疲劳性能测试结果表明:Ar气和空气环境中成形合金的沉积态和热处理态组织基本相同,沉积态组织为沿沉积方向连续生长的粗大柱状枝晶,组织细密,均匀;热处理后发生再结晶,柱状晶转变为等轴晶;2种气氛下成形件热处理后的静载拉伸性能满足锻件标准,空气环境中成形试样的拉伸强度略高于Ar气环境中成形的试样,但是前者的塑性略低;前者的疲劳性能比后者约低30%,这主要是由于空气中成形的试样中存在较多的氧化物夹杂和显微气孔等缺陷;二者的疲劳性能均低于锻件标准,主要原因是试样中存在氧化物夹杂、显微气孔等冶金缺陷以及热处理后的晶粒尺寸较大.
Inconel 718 Ni-base superalloy was laser formed in Ar gas and air atmosphere.The results of microstructure observation, tensile property and high cycle fatigue test show that the as-deposited and heat-treated alloys The structures are basically the same, and the as-deposited structure is a large columnar dendrite which grows continuously along the deposition direction. The structure is fine and uniform. The recrystallization and columnar crystal transform into equiaxed grains after heat treatment. The static load Tensile properties meet the forging standards. The tensile strength of the formed samples in the air environment is slightly higher than that of the samples formed in the Ar atmosphere, but the plasticity of the former is slightly lower. The former is about 30% less fatigue than the latter, mainly Due to the presence of more oxide inclusions and microscopic pores in the formed samples, the fatigue properties of both specimens are lower than that of forgings. The main reason is the existence of oxide inclusions, microscopic pores and other metallurgical defects As well as the larger grain size after heat treatment.