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根据实验结果和理论分析,证实了30CrNi5MoV钢经520℃回火处理后,强化机理服从Naylor模型和Langford-Cohen关系。屈服强度σ_(0.2)可由公式:表示。 用能量分析的方法给出钢的脆断模型,推导出一个新的韧性-脆性转折温度θ_(50/50)公式:公式比较全面地反映了高强钢显微组织参量与韧性的关系。 以定量金相为基础,发现钢中加Nb后,在细化奥氏体晶粒的同时,细化了马氏体板条,增大了孪晶量,改变了碳化物的大小和分布,从而提高了钢的屈服强度σ_(0.2)、断裂韧性KI_c;但转折温度θ50/50则略有升高。
According to the experimental results and theoretical analysis, the strengthening mechanism obeys the relationship between Naylor model and Langford-Cohen after 30CrNi5MoV steel tempering at 520 ℃. The yield strength σ_ (0.2) can be expressed as: The brittle fracture model of steel was given by energy analysis and a new formula of ductile - brittle transition temperature θ_ (50/50) was deduced. The formula reflects the relationship between the toughness and the microstructure parameters of high strength steel. Based on the quantitative metallography, it was found that adding Nb to the steel refined the austenite grains, refined the martensite lath, increased the amount of twins, changed the size and distribution of the carbides, Thus increasing the yield strength of steel σ_ (0.2), fracture toughness KI_c; but the turning temperature θ50 / 50 slightly increased.