利用激光选区熔化(selective laser melting,SLM)技术可近净成形GH3536合金复杂零件,其高温力学性能是能否安全服役的重要考量指标,本工作研究热处理对SLM成形GH3536合金的微观组织与高温拉伸性能的影响.在 1225℃下进行 1h热处理以探究组织性能调控机制,测试GH3536增材试样沉积态与热处理态高温下的拉伸性能,采用扫描电镜研究热处理前后增材GH3536试样的微观组织演变.结果表明:热处理可有效消除晶粒内部的胞状亚晶结构,使位错滑移能力显著增强,其在室温、650、815℃环境下断裂伸长率分别提高 75%、92%、683%;另外,柱状晶纵横比的减小使热处理试样的各向异性显著降低;断口分析表明随着拉伸环境温度的增加,热处理试样的断裂模式由沿晶断裂转变为混合断裂.
Selective laser melting(SLM)can achieve nearly net-shape complex parts of GH3536 alloy,and its high temperature mechanical properties are important indicators for safe service.The effect of heat treatment on microstructure and high temperature tensile properties of SLM GH3536 alloy were studied.The heat treatment at 1225 ℃ for 1 h was carried out to explore the regulation mechanism of microstructure and properties.The results show that heat treatment can effectively eliminate the cellular subgrain structure inside the grains,which significantly enhances the dislocation slip ability.The tensile elongations at room temperature,650 ℃ and 815 ℃ are increased by 75%,92%and 683%,respectively.In addition,the decrease of the aspect ratio of the columnar grains significantly reduces the anisotropy in the heat-treated sample.The fracture analysis shows that the fracture mode of the heat-treated sample changes from intergranular fracture to mixed fracture with the increase of tensile environment temperature.