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测定了5种不同成分Fe-Ni-C合金的M_s温度和奥氏体在M_s时的屈服强度σ0.2(M_s)。求得奥氏体在M_s温度时的固溶强化方程为:σ0.2(M_s)=25.9+3410XC+567XNi,MPa。Ni,C浓度对M_s温度的影响可以方程M_s(K)=829-8650XC-1766XNi表示,以及σ0.2(M_s)与M_s的线性关系为:σ0.2(M_s)≈210-0.323M_s(℃),MPa.说明奥氏体在M_s时的固溶强化形成马氏体相变的阻力,它和相变驱动力及与M_s均呈线性关系.含25wt-％Ni,含碳在0.11Wt-％的合金基本形成位错马氏体,仅有极少量孪晶,当含碳为0.12wt-％时,则以23.97wt-％Ni为位错和孪晶亚结构的临界含Ni量.利用Magee和Davies图导出了奥氏体的σ0.2(M_s)对Fe-Ni-C合金马氏体形态的影响图,推断出奥氏体的临界分切应力随σ0.2(M_s)的变化关系,借以解释位错型和孪晶型马氏体的形成。
The M_s temperature of 5 Fe-Ni-C alloys with different compositions and the yield strength σ 0.2 (M_s) of austenite at M_s were measured. The solution hardening equation of the austenite at the temperature of M_s is: σ0.2 (M_s) = 25.9 + 3410XC + 567XNi, MPa. The influence of Ni and C concentration on M_s temperature can be expressed by the equation M_s (K) = 829-8650XC-1766XNi, and the linear relationship between σ0.2 (M_s) and M_s is: σ0.2 (M_s) ≈210-0.323M_s ), MPa. It shows the resistance of martensite transformation formed by solid solution strengthening of austenite at M_s, and it has a linear relationship with the driving force of phase transition and M_s, and contains 25wt% Ni and 0.11Wt- % Of the alloy basically formed dislocation martensite, with only a very small amount of twins, when the carbon content is 0.12wt-%, the critical Ni content of 23.97wt-% Ni is the dislocation and twin sub-structure. Magee and Davies plots the influence of σ 0.2 (M_s) of austenite on the martensite morphology of Fe-Ni-C alloys. It is deduced that the critical shear stress of austenite varies with σ 0.2 (M_s) Relationship, in order to explain the formation of dislocation and twin-type martensite.