0.2C-5Mn-1.5Al中锰TRIP钢的显微组织及力学性能

利用相变热力学模拟计算,扫描电镜(SEM),X射线衍射仪(XRD),拉伸试验机等设备系统研究了不同退火工艺下0.2C-5Mn-1.5Al中锰TRIP钢的相变特点及组织性能,通过与不添加Al的0.2C-5Mn中锰TRIP钢进行比较,研究了Al对相变规律及工艺与组织性能的影响规律。结果表明:Al添加提高并扩大了临界区温度范围,使得中锰钢可以选择更高的临界退火温度,这有助于加快奥氏体逆相变过程,缩短退火时间;同时Al的添加促进了C,Mn元素的聚集,有效提高了残留奥氏体含量,增强了变形过程中的TRIP效应;随着退火温度的升高,0.2C-5Mn-1.5Al钢的奥氏体含量及伸长率均表现为先增加后减少的趋势,而屈服强度略微下降,拉伸强度持续增加,在760 ℃退火3 min时获得最佳的力学性能:伸长率为32%,强塑积为35 GPa·%,Al的添加有效提高了0.2C-5Mn中锰TRIP钢的综合力学性能。

Microstructure and mechanical properties of 0.2C-5Mn-1.5Al medium manganese TRIP steel

The equilibrium phase diagram, microstructure and mechanical properties of 0.2C-5Mn-1.5Al medium manganese TRIP steel under different annealing processes was studied by means of calculation of phase diagram (CALPHAD) method, scanning electron microscopy (SEM), X-ray diffractometry (XRD), and tensile test. The influence of Al on equilibrium phase diagram, intercritcal annealing process, and mechanical properties are also studied. The results show that Al addition expands the intercritical region and shift the region to higher temperatures. The intercritical annealing temperature is increased, the austenite reverse transformation process is accelerated, the annealing time is shortened, the aggregation of C and Mn elements is promoted. The retained austenite content is effectively improved, and the deformation process TRIP effect is enhanced. With the increase of annealing temperature, the austenite content and elongation of 0.2C-5Mn-1.5Al steel show a trend of increasing first and then decreasing, while the yield strength decrease slightly, tensile strength continue to increase. And annealing at 760 ℃ for 3 min, the best mechanical properties are obtained, the elongation is 32%, and the strong plastic product is 35 GPa·%, which show that the addition of Al element effectively increases the comprehensive mechanical properties of manganese TRIP in 0.2C-5Mn.