Effect of Microstructure and Precipitates on Mechanical Properties of Cr-Mo-V Alloy Steel with Different Austenitizing Temperatures
Effect of Microstructure and Precipitates on Mechanical Properties of Cr-Mo-V Alloy Steel with Different Austenitizing Temperatures
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不同奥氏体化温度Cr-Mo-V合金钢组织和析出相对力学性能的影响
DOI：
10.2355/isijinternational.isijint-2017-531
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发表时间：
2018-01-01
影响因子：
1.8
通讯作者：
Ca, Ruifang
中科院分区：
文献类型：
--
作者：
Zheng, Yaxu;Wang, Fuming;Ca, Ruifang
淬火温度对调质钢的力学性能有影响。研究了奥氏体化温度对高速列车车轴用30 NiCrMoV 12合金钢的马氏体显微组织、碳化物析出物和力学性能的影响。采用OM、FE-SEM、TEM、EBSD和EDS等分析手段对马氏体组织和碳化物析出相进行了研究。采用Thermo-Calc软件对平衡沉淀过程进行了热力学计算。结果表明，随奥氏体化温度的升高，原奥氏体晶粒、马氏体团、块状和板条均发生粗化。此外，随着回火温度的升高，回火后马氏体板条边界处析出的大尺寸碳化物数量减少，而基体中析出的小尺寸碳化物数量增加。同时，随奥氏体化温度的升高，回火过程中M23 C6向M7 C3的相变增强.粗晶粒和宽板条有利于减少板条边界处条状M23 C6碳化物的析出量，从而获得更多细小的基体析出相。在较高的回火温度下，细化回火钢中的碳化物，可在一定程度上提高钢的强度和冲击韧性。然而，细化碳化物对冲击韧性的影响程度低于粗大马氏体组织的负面影响。因此，随着奥氏体化温度的升高，韧性变差，强度提高。
The mechanical properties of as-quenched and tempered steels are affected by austenitizing temperature. The present work has investigated the effect of austenitizing temperature on martensitic microstructure, carbide precipitates and mechanical properties of 30NiCrMoV12 alloy steel for the axle of high-speed train. The martensitic microstructure and carbide precipitates were studied using OM, FE-SEM, TEM, EBSD and EDS. Thermodynamic calculation of equilibrium precipitation were carried out by Thermo-Calc software. The results showed that the prior austenite grains, martensitic packets, blocks and laths were coarsening with increasing austenitizing temperature. Besides, with increasing austenitizing temperature, after tempering the amount of large size carbides precipitated at martensitic lath boundaries decreased while the amount of small size carbides precipitated in matrix increased. Meanwhile, phase transformation from M 23 C 6 to M 7 C 3 during tempering was enhanced with increasing austenitizing temperature. Coarse grains and wide martensitic laths were beneficial to reducing the amount of strip-like M 23 C 6 carbides precipitated at martensitic lath boundaries due to the reduction of boundary area and thereby obtaining more fine precipitates in matrix. The strength and impact toughness could be improved to a certain extent by refining carbides in tempered steel with higher austenitizing temperature. However, the degree of favor-able influence on impact toughness resulting from refining carbides was lower than the negative effect from coarse martensitic structures. Therefore, the toughness is deteriorated and the strength is improved with increasing austenitizing temperature.