浇注温度与型壳温度对K4648镍基高温合金组织和性能的影响

Effect of Casting Temperature and Shell Temperature on Microstructure and Properties of K4648 Nickel-Based Superalloy

针对某型号燃气涡轮导向器用K4648镍基高温合金室温冲击韧性无法达到标准要求(冲击韧性大于20 J·cm^(-2))的问题,在不同的浇注温度与型壳温度(1 490℃/1 050℃,1 490℃/950℃,1 460℃/1 050℃)下制备了K4648镍基高温合金,并进行了固溶+标准热处理,研究了浇注温度与型壳温度对合金显微组织和冲击性能的影响,获得了优化的工艺参数。结果表明:当型壳温度或浇注温度较低时,K4648镍基高温合金的晶粒尺寸和二次枝晶间距较小,块状初生α-Cr相含量较少、尺寸较小,合金的冲击韧性较大,冲击断口处次生裂纹数量较少;优化工艺参数为型壳温度950℃、浇注温度1 490℃,此工艺参数下制备的K4648镍基高温合金的冲击韧性最大,为21.4 J·cm^(-2),满足标准要求。

Aiming at the problem that the impact toughness at room temperature of K4648 nickel-based superalloy for a certain type gas turbine guide could not meet the standard requirement(impact toughness greater than 20 J·cm^(−2)),K4648 nickel-based superalloy was prepared at different casting temperatures and shell temperatures(1490℃/1050℃,1490℃/950℃,1460℃/1050℃),and then the solid solution+standard heat treatment was carried out.The effects of casting temperature and shell temperature on the microstructure and impact properties of the alloy were studied,and the optimal process parameters were obtained.The results show that when the shell temperature or casting temperature was low,the grain size and the secondary dendrite spacing of the K4648 nickel-based superalloy,as well as the content and size of the primary bulkα-Cr phase were small.Meanwhile,the impact toughness of the alloy was large,and the number of secondary cracks at the impact fracture was small.The optimal process parameters were listed as follows:shell temperature of 950℃ and casting temperature of 1490℃.The average impact toughness of K4648 nickel-based superalloy prepared under this process parameters was the highest,which was 21.4 J·cm^(−2),meeting the standard requirement.