GH4169D合金电子束焊接接头显微组织和持久断裂特征

采用金相显微镜和扫描电镜分析了GH4169D合金电子束焊接接头的显微组织,利用显微硬度计测试了母材、热影响区和焊缝的显微硬度,采用体式显微镜和扫描电镜研究了焊接接头持久断裂特征.结果表明,GH4169D 母材中的主要析出相为1～20 μm 长的片层状晶界η相、30～80 nm 的颗粒状γ'相和少量的碳氮化物.热影响区中...

Microstructure and stress rupture characteristic of electron beam welded GH4169D alloy

The microstructure of electron beam welded GH4169 D alloy was analyzed by optical microscope(OM)and scanning electron microscope(SEM).Micro hardness of fusion zone,heat affected zone(HAZ)and base metal was examined by micro hardness tester.The stress rupture characteristic of electron beam welded GH4169 D alloy was researched by stereo microscope(SM)and SEM.Results show that The precipitated phases of GH4169 D alloy are composed of lamellarηphase with 1~20μm in length,granularγ′phase with 30~80 nm of size,and a small amount of carbonitride.The precipitated phases of heat affected zone are mainly composed of granularγ′phase with size of 10~20 nm and fewηphase on grain boundary.Dendritic structures form in fusion zone,Nb,Ti,and Al are extensively rejected into the interdendritic liquid and the eutectic constituents form with a size of 2~6μm.There are fine granularγ′phase with a size less than 10 nm in gamma dendrites.The microhardness of base metal is lower than that of heat affected zone and fusion zone.Microhardness of different zones depends on the particle size ofγ′phase.Stress rupture process is composed of creep crack growth,rapid crack growth and final fracture.Intergranular fracture occurs in creep crack growth zone,mixed intergranular and transgranular fracture occur in rapid crack growth zone and transgranular fracture occurs in final fracture zone.The creep crack imitates in the surface of HAZ of weld specimen.Because of low content of intergranularηphase and oxidation of grain boundary in crack tip,the stress rupture life and elongation are lower than those of GH4169 D base metal.