Q&P处理低碳中锰钢的显微组织与力学性能

对含硅的低碳中锰钢进行Q&P处理,获得了回火马氏体、新生马氏体和残留奥氏体的混合组织,利用SEM、TEM、XRD和拉伸试验机等检测手段研究不同热处理工艺下微观组织结构及力学性能。结果表明,随着淬火温度的提高,试验钢的抗拉强度先降低后升高,屈服强度则一直降低,总伸长率先升高后降低。淬火温度为250 ℃时,试验钢的综合力学性能最好,抗拉强度为1331 MPa,断后伸长率为17.3%,强塑积可达23 GPa·%。这主要是由于组织中一定比例的膜状残留奥氏体发挥TRIP效应,拉伸变形阶段表现出持续的加工硬化能力,获得更好的强塑匹配。淬火温度为270 ℃时,由于残留奥氏体的稳定性降低,组织内存在大量新生马氏体,使塑性下降。

Microstructure and mechanical properties of low carbon medium manganese steel treated by Q&P process

The multiphase microstructures comprising tempered matensite, fresh martensite and retained austenite with the low carbon medium manganese steel containing silicon was obtained by full austenitizing Q&P process. The microstructure and mechanical properties of the steel under different heat treatment processes were studied by means of SEM, TEM, XRD and tensile testing.The results show that with the increase of quenching temperature, the tensile strength decreases at first and then increases, the yield strength decreases,and the total elongation first increases and then decreases. When quenching temperature is 250 ℃, the tested steel gain excellent comprehensive mechanical properties with tensile strength of 1331 MPa, the total elongation of 17.3%, and the product of strength-plasticity up to 23 GPa·%. This is mainly due to the multiphase microstructures with a certain proportion of film-like retained austenite which give play to TRIP effect. The continuous work-hardening ability during the tensile deformation stagewhich is helpful for the improvement of strength and plasticity. Increasing the quenching temperature to 270 ℃, the stability of retained austenite decreases, a large number of fresh martensite exists, which both makes the plasticity decrease.