热等静压对激光选区熔化成形GH4169合金持久性能的影响

Effects of Hot Isostatic Pressing on Stress Rupture Properties of GH4169 Alloy Manufactured by Selective Laser Melting

采用激光选区熔化(SLM)成形技术制备了GH4169合金,运用金相显微镜(OM)、扫描电子显微镜(SEM)、电子背散射衍射(EBSD)和透射电镜(TEM)等分析手段分析了热等静压对SLM成形GH4169合金组织及持久性能的影响规律。结果表明:沉积态合金组织中,沿沉积方向的晶粒为柱状晶,晶粒内枝晶组织细小,枝晶间分布大量Laves相;热等静压处理可有效消除组织中气孔缺陷,溶解大部分Laves相,促使组织晶粒等轴化,并减少后续980℃固溶处理过程中δ相在晶内的析出;热等静压处理能提高合金的持久寿命,但会降低合金的持久塑性。

GH4169 alloy samples were manufactured by selective laser melting(SLM).The microstructure evolution and stress rupture properties of samples during hot isostatic pressing(HIP)and heat treatment(HT)process were analyzed by OM,SEM,EBSD and TEM.The results show that most of grains of the as-built samples are elongated in the building direction,exhibiting a very fine cellular-dendritic structure with fine Laves phase precipitating in the interdendritic region.Most of porosities and Laves precipitates disappear after HIP,and the microstructure parallel to the building direction is transformed into equiaxed grains.Besides,the HIP treatment can significantly lower the precipitation of needle-likeδphase in the grain during the subsequent solution treatment at 980℃for 1 hour.The HIP treatment can improve the stress rupture lifetime,but decrease the elongation slightly.