热处理工艺对钒微合金化冷轧TRIP钢组织性能影响研究

Effects of Heat Treatment Processes on Microstructures and Properties of the Vanadium-alloyed Cold-rolled TRIP Steel

采用盐浴热处理方法配合性能检测及显微组织分析方法研究了热处理工艺对含钒冷轧TRIP钢组织性能的影响,结果表明试验钢在所采用的热处理工艺下其抗拉强度均达到700 MPa,且在780℃×60 s+400℃×180 s工艺下获得最佳综合性能,屈服强度、抗拉强度、断后伸长率、强塑积分别为514 MPa、738 MPa、29%、21 402 MPa·%;随着两相区退火温度的升高,两相区奥氏体所占的体积分数也越高,使最终组织中贝氏体及马氏体等强化相含量增多,造成试验钢强度上升、塑性下降;钒在试验钢中对残余奥氏体的积极作用并未体现,可能与退火时间较短和贝氏体区等温时钒碳(氮)化物重新析出消耗残余奥氏体中碳原子造成其含量及稳定性下降有关。

The microstructures and properties of vanadium-alloyed cold wiled TR/P steel were investigated by salt-bath heat treatment and methods of property testing and microstructure observation. The results show that all the tensile strength of the samples can reach 700 MPa in the certain heat treatment, and the best mechanical properties with 514 MPa yield stress, 738 MPa tension stress, 29% elongation and 21 402 MPa . %, respectively, can be achieved. As the intercritical annealing temperature increasing, the volume fraction of austenite increases accordingly. So the hardening phases such as bainite and martensite increase to make the strength increasing and the ductility decreasing. The positive effect of vanadium on austenite is not apparent, which may be associated with the short annealing time and the precipitation of vanadium carbides in the bainite zone which can reduce the stability of retained austenite by consuming the carbon element.