1.5Al中锰钢短时临界退火后的组织与性能

Microstructure and properties of 1.5Al medium-manganese steel after short time intercritical annealing

应用热力学软件、扫描电镜(SEM)、X射线衍射仪(XRD)以及拉伸试验等方法研究了0.2C-5Mn-0.5Si-1.5Al中锰TRIP钢的热力学工艺窗口、微观结构及力学性能,并在此基础上分析了短时临界退火温度对组织演变和力学性能的影响规律。热力学计算结果表明,最佳临界退火温度范围为640~670℃,实际最佳退火温度右移约70℃。低温阶段(700℃)碳化物未完全溶解,高温阶段(760~820℃)奥氏体稳定性降低,组织中出现马氏体,分别对应最佳工艺窗口两侧。730℃临界退火后,碳化物完全溶解且奥氏体足够稳定,组织由铁素体和奥氏体构成,可获得最佳力学性能,抗拉强度约1041 MPa,屈服强度921 MPa,伸长率42%,强塑积接近43 GPa·%。

Thermodynamic process window, microstructure and mechanical properties of 0.2 C-5 Mn-0.5 Si-1.5 Al medium manganese TRIP steel were studied by means of thermodynamic software, scanning electron microscopy(SEM), X-ray diffractometer(XRD) and tensile test, based on which, the effect of short time intercritical annealing temperature on microstructure evolution and mechanical properties of the tested steel was analyzed. The thermodynamic calculation results show that the optimal intercritical annealing temperature range is 640-670 ℃, and the actual optimal annealing temperature shifts to the right about 70 ℃. At the low temperature stage(700 ℃), the carbides are not completely dissolved, while at the high temperature stage(760-820 ℃), the stability of austenite decreases and martensite appears in the microstructure, which corresponding to both sides of the optimal process window respectively. After intercritical annealed at 730 ℃, the carbides are completely dissolved and the austenite is stable enough, the microstructure is composed of ferrite and austenite, and the optimal mechanical properties can be obtained, with the tensile strength of 1041 MPa, the yield strength of 921 MPa, the elongation of 42%, and the strength-elongation product being close to 43 GPa·%.