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结合熔模铸造条件下K424高温合金出现的高温持久性能下降的问题,对所存在的一些缺陷进行了研究,对缺陷的形态、成因以及对高温持久性能的影响进行了阐述。借助扫描电子显微镜、显微硬度计等仪器对K424合金试棒进行了观察和测试。结果表明,试棒的枝晶间存在显微缩松。显微缩松附近有呈规则正八面体的MC碳化物聚集。Cr元素发生了较严重的偏析。显微缩松是相邻枝晶臂搭接,剩余液相被封闭在晶间区域收缩而成。显微缩松在高温持久测试时引起应力集中,作用于薄弱的晶间组织,导致高温持久性能不足。
In combination with the problem of the decrease of high temperature endurance performance of K424 superalloy under investment casting conditions, some existing defects were studied, and the defects morphology, genesis and the effect on the high temperature endurance performance were described. The K424 alloy test rod was observed and tested by means of scanning electron microscope and microhardness tester. The results show that there is micro-shrinkage between the dendrites of the test rods. There is regular octahedron MC carbide aggregation near the microscopic collapse. Cr element occurred more serious segregation. Microcondensation is adjacent dendrite arm lap, the remaining liquid phase is enclosed in the intergranular region contraction. Micro-shrinkage causes stress concentration during long-term testing at high temperatures, acting on weak intergranular tissues, resulting in insufficient long-term performance at high temperatures.