In Situ Local Measurement of Austenite Mechanical Stability and Transformation Behavior in Third-Generation Advanced High-Strength Steels
In Situ Local Measurement of Austenite Mechanical Stability and Transformation Behavior in Third-Generation Advanced High-Strength Steels
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DOI：
10.1007/s11661-018-4660-x
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发表时间：
2018-05
期刊：
影响因子：
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通讯作者：
F. Abu-Farha;Xiaohua Hu;Xin Sun;Yang Ren;L. Hector;G. Thomas;Tyson W. Brown
中科院分区：
文献类型：
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作者：
F. Abu-Farha;Xiaohua Hu;Xin Sun;Yang Ren;L. Hector;G. Thomas;Tyson W. Brown
奥氏体机械稳定性，即，研究了两种第三代先进高强度钢（3GAHSS）在准静态单轴拉伸条件下残余奥氏体体积分数（RAVF）随应变的变化以及相变行为：1200级两相中Mn（10wt%）TRIP钢和980级经淬火和配分热处理的三相TRIP钢。中Mn（10 wt %）TRIP钢通过传播不稳定性（Lüders和Portevin Le Châtelier样带）不可逆地变形，而980级TRIP钢均匀地变形直至颈缩。这些钢的显着不同的变形行为需要开发一种新的原位实验技术，耦合体同步辐射X射线衍射测量RAVF与表面应变测量使用立体数字图像相关的光束照射面积。与新技术的测量结果进行比较，从一个更传统的方法，其中应变测量在整个量规区域，而RAVF测量是相同的，在新技术。确定了不同的测量技术在测量具有均匀和不均匀变形行为的钢的相变行为时的适当性。扩展的新原位技术的测量奥氏体相变下不同的变形模式和更高的应变速率进行了讨论。
Austenite mechanical stability,i.e., retained austenite volume fraction (RAVF) variation with strain, and transformation behavior were investigated for two third-generation advanced high-strength steels (3GAHSS) under quasi-static uniaxial tension: a 1200 grade, two-phase medium Mn (10 wt pct) TRIP steel, and a 980 grade, three-phase TRIP steel produced with a quenching and partitioning heat treatment. The medium Mn (10 wt pct) TRIP steel deforms inhomogeneouslyviapropagative instabilities (Lüders and Portevin Le Châtelier-like bands), while the 980 grade TRIP steel deforms homogenously up to necking. The dramatically different deformation behaviors of these steels required the development of a newin situexperimental technique that couples volumetric synchrotron X-ray diffraction measurement of RAVF with surface strain measurement using stereo digital image correlation over the beam impingement area. Measurement results with the new technique are compared to those from a more conventional approach wherein strains are measured over the entire gage region, while RAVF measurement is the same as that in the new technique. A determination is made as to the appropriateness of the different measurement techniques in measuring the transformation behaviors for steels with homogeneous and inhomogeneous deformation behaviors. Extension of the newin situtechnique to the measurement of austenite transformation under different deformation modes and to higher strain rates is discussed.