温轧及逆相变退火对中锰钢组织和力学性能的影响

Effect of warm-rolling and intercritical annealing on microstructure and mechanical properties of medium-Mn steel

采用单轴拉伸及TEM、XRD等实验方法分析研究了0.1C-5Mn中锰钢温轧后逆相变退火处理对其组织和性能的影响规律。结果表明：实验钢温轧后退火处理可获得等轴状与一定量板条状共存的奥氏体＋铁素体的复合组织形貌。随着退火时间延长,逆转变奥氏体的含量增多、尺寸增大,这使得奥氏体的稳定性逐渐降低,抗拉强度逐渐提高,而屈服强度、伸长率及强塑积则逐渐降低;在退火时间为5min时,可获得高达40GPa·%的强塑积。与冷轧退火样相比,温轧退火样具有更为优异的塑性和强塑积,强塑积可提高20%以上。因此,温轧工艺具有简化中锰钢生产工艺流程、并进一步改善其力学性能的良好潜力。

Effect of warm-rolling and subsequent intercritical annealing time at 650℃ on microstructure and mechanical properties of a medium-Mn steel 0.1 C-5 Mn was investigated by using uniaxial tensile testing,transmission electron microscopy（TEM）and X-ray diffraction（XRD）analysis.The results show that a duplex microstructure having both equiaxed and lamellar morphologies of reverted austenite and ferrite is obtained after intercritical annealing of the warm-rolled steel sheet.The amount of reverted austenite and its size increase with increasing annealing time,which causes a decrease of the mechanical stability of austenite and thus an increase of ultimate tensile strength（UTS）while a decrease of yield strength,total elongation（TEL）and the product of UTS to TEL（UTS×TEL）.An excellent combination of strength and ductility of 40 GPa·% could be obtained after a short time annealing of 5 min.The combination of strength and ductility（UTS×TEL）could be increased by about20%for the warm-rolled steel sheet compared to that of the cold-rolled steel sheet.It is thus proposed that warm-rolling is a promising way to simplify the traditional multi-stage rolling and annealing processes of medium-Mn steels as well as further enhancing it mechanical properties.