摘要
对65Cr5Mo3W2VSiTi(LM2)钢常规淬火组织和部分等温淬火组织的冲击韧性和断裂韧性进行了测试,对比研究了显微组织(主要指 B_l和 A_R 数量)和回火温度对LM2钢下贝氏体/马氏体(B_l/M)复相组织韧性的影响。用连续扫描拉伸技术分析了裂纹的萌生、扩展至断裂全过程与显微组织的关系。通过 U 型缺口试样的示波单冲试验,分析了显微组织对裂纹萌生功和扩展功的影响及其对缺口冲击韧性的贡献。试验结果表明,含有40%～60%B_1的复相组织随后200℃回火,对钢有显著地韧化效果。文中还较详细地探讨了高碳高合金钢中复相组织的断裂机制。
The comprehensive tests on the toughness and fracture toughness were carried out on the microstructure of conventional quench hardening and partial austempering of 65Cr5Mo3W2VSiTi(LM2) steel.It is studied compara- tively on its change rules and the relationship between microstrueture(including B_l and A_R),tempering temperature and toughness of B_l/M duplex structu re in the LM 2 steel with the SEM continuous tensile technique.It is observed directly about the whole process of microcrack initiation,propagation and final fracture and analysed its relationship to microstructure.With the single impact test of U type notch standard specimen,it is evaluted about the in flu- enee of microstructure on the energy of crack initiation(E_i) and propagation (E_p)and its contribution to the notch impact toughness.The results show that toughness of mixed structure of 40%～60% B_1 is best after tempering at low tem- perature.Authors discussed the mechanism of fracture in the duplex structure of high carbon alloy steel.
关键词
韧性
贝氏体
马氏体
LM2钢
bainite/martensite duplex structure
toughness
65Cr5Mo3W2-VSiTi steel
