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本文以中高碳合金钢5CrNiMo进行试验,全面探索了马氏体贝氏体复合组织的强韧性能。实验结果表明:当低温回火马氏体中存在少量(25～40%)下贝氏体时,材料保持有超高强度的特点,而韧性K_(1c)和CVN以极大的幅度上升,塑性和疲劳性能显著改善。这种复合组织经中温回火后,σ_s下降极少,而韧性又明显上升,可获得最佳的强韧配合。通过显微和断口分析,研究了马氏体中存在不同量的下贝氏体时强韧性变化的微观机理。对马氏体中存在少量上贝氏体时强韧性的变化规律及其微观机理,也进行了探讨。
In this paper, high-carbon alloy steel 5CrNiMo test to fully explore the martensite bainite toughness of the composite structure. The experimental results show that when a small amount of (25 ~ 40%) lower bainite exists in the low temperature tempered martensite, the material maintains the characteristics of ultrahigh strength, while the toughness K_ (1c) and CVN increase with great amplitude, Plasticity and fatigue properties are significantly improved. After the tempering of this kind of composite structure by medium temperature tempering, σ_s decreases very little, but the toughness increases obviously, obtains the best strong cooperation. By microscopic and fracture analysis, the microscopic mechanism of the change of toughness in the presence of different amounts of lower bainite in martensite was studied. On the martensite in the presence of a small amount of bainite strength and toughness of the law of change and its micro-mechanism, also were discussed.