Co对4Cr5Mo2V钢组织和强韧性的影响

Effect of Co on microstructure and strength and toughness of 4Cr5Mo2V steel

采用OM、SEM、EDS、硬度测试、室温冲击及高温拉伸等方法研究了Co对4Cr5Mo2V钢的组织和强韧性的影响。结果表明:经1010℃淬火30 min,4 Cr5Mo2V-Co钢未溶碳化物数量更多,马氏体板条更细;510~600℃回火时,4Cr5Mo2V-Co钢的回火硬度较4Cr5Mo2V钢高出1~2 HRC,但二者冲击性能相当;相同初始硬度条件下,4 Cr5Mo2V-Co钢具有更高的高温强度,这是因为Co元素的添加促进了4Cr5Mo2V-Co钢二次硬化碳化物的形核速率,并能降低碳化物的粗化速率,从而提高了4Cr5Mo2V-Co钢的强度。

Effect of Co on microstructure,strength and toughness of the 4Cr5Mo2V steel was studied by means of OM,SEM,EDS,hardness test,room temperature impact and high temperature tensile tests.The results show that the 4Co5Mo2V-Co steel has more undissolved carbides and the martensite laths are thinner after quenching at 1010℃for 30 min.When tempered at 510-600℃,the hardness of the 4Co5Mo2V-Co steel is 1-2 HRC higher than that of the 4Co5Mo2V steel,while the two steels have similar impact properties.The 4Cr5Mo2V-Co steel has higher high-temperature strength under the same initial hardness,which is because the addition of Co promotes the nucleation rate of secondary hardened carbides in the 4Cr5Mo2V-Co steel,and reduces the coarsening rate of carbides,thereby improving the strength of the 4Cr5Mo2V-Co steel.