Effect of C Content on the Microstructure and Stress Rupture Properties of Nickel-Based Superalloy K4750
Effect of C Content on the Microstructure and Stress Rupture Properties of Nickel-Based Superalloy K4750
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DOI：
10.1007/s11665-022-07628-0
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发表时间：
2022-11
影响因子：
2.3
通讯作者：
Xiaoxiao Li;Meiqiong Ou;Xun Yu;Xianchao Hao;Yingche Ma
中科院分区：
文献类型：
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作者：
Xiaoxiao Li;Meiqiong Ou;Xun Yu;Xianchao Hao;Yingche Ma
采用扫描电子显微镜、电子探针、电子探针和持久试验等手段，研究了C含量对K4750镍基高温合金组织和持久性能的影响。随着C含量的增加，实验合金中MC和M23C6碳化物的尺寸和数量增加，MC碳化物的形态由小块状或棒状转变为大块状或骨架。MC碳化物对晶界迁移的抑制作用使铸态合金的晶粒度与C含量成反比。当C含量从0.07wt.%增加到0.12wt.%时，K4750合金在750C/430℃下的持久寿命从160.7提高到222.0 h，然后降低到184.4 h，延伸率从5.1%增加到11.5%，然后降低到9.8%。K4750合金持久性能的差异可归因于不同C含量对碳化物析出特征的影响。适量增加MC和M23C6碳化物可以有效地钉扎晶界，减少微孔洞和微裂纹的形成，有利于K4750合金的应力性能。反之，当碳化物的尺寸和数量增加过多时，在持久试验过程中可能成为潜在的裂纹源。
The effect of C content on the microstructure and stress rupture properties of nickel-based superalloy K4750 was studied by SEM, EBSD, TEM, EPMA and stress rupture tests. With the increase in C content, the size and quantity of MC and M23C6carbides in experimental alloys increased, and the morphology of MC carbides changed from small blocky or rod to large blocky or skeleton. The inhibition of MC carbides on grain boundary migration made the grain size of as-cast alloys inversely proportional to C content. As C content went from 0.07 to 0.10 wt.% and then to 0.12 wt.%, the stress rupture life of K4750 alloy at 750 °C/430 MPa increased from 160.7 to 222.0 h, and then decreased to 184.4 h, and the elongation increased from 5.1 to 11.5% and then decreased to 9.8%. The difference of stress rupture properties of K4750 alloys could be attributed to the influence of varied C content on carbides precipitation characteristics. The moderate increase in MC and M23C6carbides could effectively pin grain boundaries and reduced the tendency of forming micro-voids and micro-cracks, which was beneficial to stress properties of K4750 alloy. On the contrary, when the size and quantity of carbides increased excessively, they could become potential crack sources in the process of stress rupture tests.