50CrMo和70CrNiMoV钢的组织与强韧性

研究了50CrMo钢和70CrNiMoV钢不同热处理状态的显微组织,探讨了合金化元素配伍对两种钢显微组织的影响,分析了两种钢的显微组织与其强韧性的关系。研究结果表明:50CrMo钢有较明显的自回火现象——淬态组织中有ε碳化物析出,回火时析出物易于聚集长大,造成强度、硬度迅速下降,但有较高的韧性;70CrNiMoV钢的淳火组织中亦有少量弥散析出物,但析出物不易聚集长大,回火稳定性好。另外,Ni加入含Cr钢中有促进M_(23)C_6型碳化物形成而减少MC型碳化物的效应。

MICROSTRUCTURE & STRENGTH-TOUGHNESS OF 50CrMo & 70CrNiMoV STEELS

The microstructure and strength-toughness of 50CrMo steels in various heat-treated states have been studied. Effect of the compatibility of alloy's elements on the microstructure of the two steels has been discussed. The relationship of microstructure and strength-toughness is analyzed. It shows that there is remarkable self-tempering in quenching structure of 50CrMo steel, i.e. a considerable number of ε-carbide particles precipitate in quenching martensite laths. These carbide particles gather and grow up easily during tempering. It results in drastic drop of strength and hardness, but favorable increasing toughness. On the contrary, there are quite stable strength and hardness in tempering of 70CrNiMoV steel, owing to multi-elements function. It also shows a tendency to promote formation of M_(23)~-C_6 type carbide and cantrol MC type carbide formation when Ni was added to the steel containing Cr.