选区激光熔化成形Hastelloy X合金持久性能研究

Stress-rupture Properties of Hastelloy X Alloy by Selective Laser Melting

通过对选区激光熔化成形Hastelloy X合金持久试样进行组织性能与断口分析,研究Hastelloy X合金持久断裂模式及影响持久性能的主要因素,并对选区激光熔化成形与后处理过程进行组织演变规律追踪。分析认为,选区激光熔化成形Hastelloy X合金持久断裂模式为微孔聚合型沿晶韧窝断裂,碳化物的形态与数量、晶粒形态和取向是影响持久性能的主要因素。晶界薄膜状和较大颗粒状碳化物主要产生在热处理与热等静压冷却阶段,后续将调整后处理过程冷却速率,在碳化物析出峰附近快速冷却,控制碳化物形态与数量以有效提升Hastelloy X合金持久性能。

In this study,fracture and microstructure analysis were conducted on Hastelloy X alloy formed by selective laser melting(SLM)after high-temperature stress-rupture testing to research the stress-rupture fracture modes and the main factors of the stress-rupture properties.In addition,the microstructure evolution during selective laser melting forming and post-treatment were tracked.The results indicate that the stress-rupture fracture mode of Hastelloy X alloy by selective laser melting is micro-pore aggregation fracture with the intercrystalline dimples.The morphology and amount of carbides,as well as the morphology and orientation of grains,are the main factors that affect the stress-rupture properties of Hastelloy X alloy.In the cooling stage of heat-treatment and hot iso-static pressing,film-like carbides and granular carbides with larger size substantially precipitate along the grain boundaries,reducing the stress-rupture properties.It is suggested that the cooling rate of post-treatment should be adjusted and the alloy should cool rapidly at the temperature near the precipitation peak of carbides to control the morphology and amount of carbides and improve the stress-rupture properties.