两相区退火处理含铝中锰钢的组织和力学性能

为了研究两相区退火处理对冷轧含铝中锰钢(0.2C-0.6Si-5Mn-1.2Al)(质量分数,%)微观组织和力学性能的影响规律,利用SEM、XRD及单轴拉伸等试验方法表征了不同工艺状态后的微观组织及测试了拉伸性能。结果表明,冷轧试验钢在退火过程中组织发生奥氏体逆转变,在退火温度为670℃、退火时间为10min时可获得较佳的力学性能,即抗拉强度达到1276 MPa,总伸长率达到51.8%,强塑积高达66.1GPa·%。随着退火温度升高,残余奥氏体组织逐渐粗化且向马氏体组织转变,机械稳定性逐渐降低。残余奥氏体机械稳定性主要受残余奥氏体中碳质量分数及其晶粒尺寸的影响,而残余奥氏体中锰质量分数对其影响较小。

Microstructure and mechanical properties of intercritically annealed Al-contain medium Mn steel

In order to investigate the effect of intercritical annealing temperature on the microstructure and mechanical properties of a newly designed cold-rolled aluminum-containing medium Mn steel (0.2C-0.6Si-5Mn-1.2Al)(mass percent,%),the microstructure was characterized by scanning electron microscopy (SEM) and X-ray diffraction(XRD). The mechanical properties were tested by uniaxial tensile test. The results show that an excellent combination of ultimate tensile strength (UTS) of 1 276 MPa,total elongation (TEL) of 51.8% and UTS×TEL of 66.1 GPa·% could be obtained after annealing at 670 ℃ for 10 min. The inverted austenite of the cold-rolled steel gradually coarsenes and transforms into martensite,and the mechanical stability gradually decreased with increasing intercritical annealing temperature. The mechanical stability of inverted austenite is mainly affected by the content of C in retained austenite and the grain size,while the content of Mn in the retained austenite has little effect on it.