Yang Yonggang, Zuo Wangnan, Liu Yu, Ge Yunzong, Yang Zhiqiang, Han Jiansheng, Mi Zhenli
National Engineering Research Center for Advanced Rolling and Intelligent Manufacturing, University of Science and Technology Beijing, Beijing 100083, China.
Central Iron & Steel Research Institute, Beijing 100081, China.
Micromachines (Basel). 2024 Aug 21;15(8):1052. doi: 10.3390/mi15081052.
Friction stir processing (FSP) manufacturing technology was used to fabricate medium Mn advanced high-strength steel in this study. The mechanical properties and microstructure of the steel fabricated using FSP were investigated. The steel obtained a total elongation of 35.1% and a tensile strength of 1034.6 MPa, which is about 59% higher than that of the steel without FSP. After FSP, a gradient structure occurs along the thickness direction. Specifically, across the thickness direction from the base material zone to the transition zone and finally to the stirring zone, both the grain size and austenite fraction decrease while the dislocation density increases, which results from the simultaneous effect of severe plastic deformation and recrystallization during FSP. Due to the gradient structure, an obvious difference in the strain across the thickness direction of the steel occurs during the deformation process, resulting in significant hetero-deformation-induced (HDI) strengthening. The deformation mechanism analysis reveals that HDI strengthening and dislocation strengthening are the main factors in the improvement in the strength-ductility balance. The obtained knowledge sheds light on the process of fabricating medium Mn steels with excellent properties using FSP manufacturing technology.
本研究采用搅拌摩擦加工（FSP）制造技术制备中锰先进高强度钢。对采用FSP制备的钢的力学性能和微观结构进行了研究。该钢的总伸长率为35.1%，抗拉强度为1034.6MPa，比未进行FSP处理的钢高约59%。FSP处理后，沿厚度方向出现梯度结构。具体而言，从基材区到过渡区再到搅拌区，沿厚度方向，晶粒尺寸和奥氏体分数均减小，而位错密度增加，这是FSP过程中严重塑性变形和再结晶共同作用的结果。由于这种梯度结构，在变形过程中，钢的厚度方向上的应变出现明显差异，从而导致显著的异质变形诱导（HDI）强化。变形机制分析表明，HDI强化和位错强化是改善强度-塑性平衡的主要因素。所获得的知识为利用FSP制造技术制备具有优异性能的中锰钢的工艺提供了启示。
