Thermal and Mechanical Stability of Retained Austenite in Aluminum-containing Multiphase TRIP Steels
Thermal and Mechanical Stability of Retained Austenite in Aluminum-containing Multiphase TRIP Steels
复制标题
DOI：
10.2355/isijinternational.42.1565
复制
发表时间：
2002-12
影响因子：
1.8
通讯作者：
S. Zwaag;Lie Zhao;S. O. Kruijver;J. Sietsma
中科院分区：
文献类型：
--
作者：
S. Zwaag;Lie Zhao;S. O. Kruijver;J. Sietsma
残余奥氏体的稳定性是理解相变诱发塑性（TRIP）效应的关键。在这项工作中，无论是热稳定性和机械稳定性进行了研究，热磁以及原位常规X射线衍射和微同步辐射衍射测量。研究了0.20C-1.52Mn-0.25Si-0.96Al（wt%）TRIP钢在5 T恒磁场下5 ~ 300 K温度范围内的热稳定性。结果表明，当冷却到5 K时，几乎所有的奥氏体都热转变为马氏体，Ms和Mf温度分别为355和115 K。基于热力学的模型很好地描述了分数与温度关系的转变动力学。通过对0.17C-1.46Mn-0.26Si-1.81Al（wt%）钢的原位常规X射线衍射和同步辐射衍射测量，发现残余奥氏体的体积分数随应变的增加而减少，符合Ludwigson和Berger关系。衍射测量还表明，机械稳定性取决于晶粒相对于外加应力方向的取向，并且发现45°或60°角的奥氏体晶粒比更小或更大角度的奥氏体晶粒更稳定。热实验和衍射实验均表明，残余奥氏体的平均碳浓度随温度降低或应力增加而增加。因此，残余奥氏体的热稳定性和机械稳定性归因于碳在不同奥氏体晶粒上的分布。
Stability of retained austenite is the key issue to understand transformation-induced plasticity (TRIP) effect. In this work, both thermal stability and mechanical stability are investigated by thermo-magnetic as well as in situ conventional X-ray diffraction and micro synchrotron radiation diffraction measurements. The thermal stability in a 0.20C-1.52Mn-0.25Si-0.96Al (wt%) TRIP steel is studied in the temperature range between 5 and 300 K under a constant magnetic field of 5T. It is found that almost all austenite transforms thermally to martensite upon cooling to 5 K and M S and M f temperatures are analyzed to be 355 and 115 K. Transformation kinetics on the fraction versus temperature relation are well described by a model based on thermodynamics. From the in situ conventional X-ray and synchrotron diffraction measurements in a 0.17C-1.46Mn-0.26Si-1.81Al (wt%) steel, the volume fraction of retained austenite is found to decrease as the strain increases according to Ludwigson and Berger relation. The diffraction measurements also show that the mechanical stability depends on the orientation of the grain with respect to the direction of the applied stress, and the austenite grains at an angle of 45° or 60° were found to be more stable than those at lower or higher angles. Both thermal and diffraction experiments show an increase in the average carbon concentration of the remaining austenite with lowering temperature or increasing stress. Thermal and mechanical stability of retained austenite is therefore attributed to the carbon distribution over different austenite grains.