KINETICS OF STRAIN-INDUCED MARTENSITIC NUCLEATION
KINETICS OF STRAIN-INDUCED MARTENSITIC NUCLEATION
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DOI：
10.1007/bf02672301
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发表时间：
1975-01-01
期刊：
影响因子：
--
通讯作者：
COHEN, M
中科院分区：
文献类型：
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作者：
OLSON, GB;COHEN, M
亚稳马氏体中剪切带的交叉点是应变诱发马氏体形核的有效位置。剪切带的形式可以是ε'（hcp）马氏体、机械孪晶或密集的层错束。 假设剪切带相交是应变诱导形核的主要机制，通过考虑剪切带形成过程、剪切带相交的概率和相交产生马氏体胚的概率，推导出马氏体体积分数与塑性应变的关系式。所得到的转换曲线具有S形形状，并且通常在100%以下接近饱和。饱和值和接近饱和的速率由两个与温度有关的参数决定，这两个参数与Fee-Bee化学驱动力和奥氏体层错能有关。拟合的表达式，304不锈钢上的可用数据给出了很好的协议，个人的转变曲线的形状，以及导出的参数的温度依赖性。它的结论是，温度依赖性的转变动力学（TRIP钢的发展中的一个重要问题），可以通过适当的成分控制，减少费，bec，和hep熵差最小化。
Intersections of shear bands in metastable austenites have been shown to be effective sites for strain-induced martensitic nucleation. The shear bands may be in the form of ε’ (hcp) martensite, mechanical twins, or dense bundles of stacking faults. Assuming that shear-band intersection is the dominant mechanism of strain-induced nucleation, an expression for the volume fraction of martensite vs plastic strain is derived by considering the course of shear-band formation, the probability of shear-band intersections, and the probability of an intersection generating a martensitic embryo. The resulting transformation curve has a sigmoidal shape and, in general, approaches saturation below 100 pct. The saturation value and rate of approach to saturation are determined by two temperature-dependent parameters related to the fee-bee chemical driving force and austenite stacking-fault energy. Fitting the expression to available data on 304 stainless steels gives good agreement for the shape of individual transformation curves as well as the temperature dependence of the derived parameters. It is concluded that the temperature dependence of the transformation kinetics (an important problem in the development of TRIP steels) may be minimized by decreasing the fee, bec, and hep entropy differences through proper compositional control.