激光选区熔化Hastelloy X合金的显微组织与拉伸性能的各向异性

Anisotropy of Microstructure and Mechanical Properties of Hastelloy X Alloy Produced by Selective Laser Melting

采用激光选区熔化(selective laser melting, SLM)技术制备Hastelloy X合金并进行热处理与热等静压。分析晶粒组织与析出相特性,研究合金的常高温拉伸性能。结果表明:热处理+热等静压后,纵向截面中部分晶粒为柱状晶形态,而横向截面中晶粒基本为等轴晶组织;立方结构的碳化物在晶粒内部和晶界上大量析出,并在晶界处呈连续分布;与SLM成形Hastelloy X横向试棒相比,纵向试棒的抗拉强度低而塑性较高;横向与纵向试棒的拉伸断口均呈现韧性断裂特征;SLM成形Hastelloy X合金室温拉伸性能达到锻造Hastelloy X合金的95%以上,而600℃高温抗拉强度约为锻造合金的85%。

Selective laser melting （SLM） was used to fabricate Hastelloy X alloy. The characteristics of grains and precipitates in Hastelloy X alloy processed by heat treatments （HT） and hot isostatic pressing （HIP） was analyzed. Furthermore, the tensile property of Hastelloy X alloys at ambient temperature and elevated temperature was investigated. Some grains exhibit columnar crystal morphology in vertically built samples, while file grains are equiaxial in horizontally built samples. The carbide phases with cubic structure are formed within grains and at grain boundaries simultaneously after a combination of liT and HIP. The horizontally built samples exhibits high tensile strength and low plasticity compared with the vertically built ones. Both of vertically built and horizontally built samples show predominantly ductile failure as characterized by dimpled microstructure. The tensile strength of Hastelloy X alloy at ambient temperature produced by SLM is 95% higher than that of hot forged alloy, while the tensile strength at 600℃ is about 85% of hot forged ones.