燃气轮机隔热板GH22合金的组织和力学性能

Microstructure and Mechanical Properties of Alloy GH22 as Insulate Plates Against Heat in Industrial Gas Turbine

采用真空感应熔炼的方法制备GH22母合金,然后真空感应重熔浇注成等轴晶成形试棒,测试其室温拉伸、高温拉伸和持久性能。利用熔模失蜡精密铸造技术生产了重型燃机GH22隔热板铸件,对隔热板不同部位进行了宏观晶粒度、光学金相、扫描电镜及能谱分析。从国产、进口隔热板底板分别取样加工成力学性能试样,进行了室温拉伸、高温拉伸和高温持久性能测试。结果表明:国产GH22母合金的成分和性能满足《GH22燃气轮机隔热板精密铸造技术条件》要求。国产铸件取样试样的宏观晶粒度、室温拉伸、高温拉伸性能与国外铸件相当。国产铸件具有更高的高温持久强度,这主要是由于国产GH22母合金中碳含量更高,合金组织中在枝晶间和晶界处析出更多的碳化物相。

The tensile properties at room and high temperatures were tested with equiaxed specimens of the alloy GH22 made by vacuum induction melting method.The insulate plates against heat used in industrial gas turbine were manufactured by investment casting.The macro grain and microstructure were analyzed by optical metallography（OM）,scanning electron microscopy（SEM） and energy dispersive spectrum（EDS）.The tensile and stress-rupture properties of specimens cut from domestic and foreign parts were also tested,respectively.The results show that the composition and tensile properties can meet the specification of insulate plates against heat of alloy GH22.The grain size and tensile properties both at room-temperature and high-temperature are comparable between domestic parts and foreign parts.The increment in high temperature stress rupture properties of domestic parts with higher carbon contents is induced by more carbides precipitated at the interdendrites and grain boundaries.