1500双相钢的微观组织及力学性能研究

Study on microstructure and mechanical properties of 1500 dual-phase steel

对Fe-C-Mn-Si系双相(dual-phase,DP)钢通过Nb的微合金化以及设计后续连续退火热处理工艺,制备出抗拉强度达1500 MPa级Nb微合金化的Fe-C-Mn-Si-Nb系DP钢。利用扫描电子显微镜、透射电子显微镜、万能拉伸试验机等设备系统研究了不同退火温度以及Nb微合金化对Fe-C-Mn-Si系DP钢微观组织及力学性能的影响。实验结果表明,Nb的微合金化使奥氏体、铁素体和马氏体晶粒细化。在800~850℃退火温度范围内,随着退火温度的升高,试样的屈服强度逐渐增加,抗拉强度先增加后减少,含Nb钢850℃退火,240℃过时效后的抗拉强度和伸长率分别为1537.6 MPa和15.27%。经850℃退火后,含Nb钢的抗拉强度和伸长率相较无Nb钢的分别提升41.1 MPa和2.4%。

The 1500 MPa grade tensile strength Fe-C-Mn-Si dual-phase(DP)steel was prepared by Nb microalloying and subsequent continuous annealing treatment process.The effects of annealing temperature and Nb microalloying on the microstructure and mechanical properties of Fe-C-Mn-Si DP steel were systematically studied by means of scanning electron microscope,transmission electron microscope and universal tensile tester.The results show that Nb microalloying refines austenite grains,ferrite and martensite.In the annealing temperature range of 800-850℃,with the increase of annealing temperature,the yield strength of the sample increases gradually,both the tensile strength and the elongation decrease firstly and then increase.The tensile strength and elongation of Nb microalloyed steel by annealing at 850℃and overaging at 240℃are 1537.6 MPa and 15.27%,respectively.After annealing at 850℃,both the tensile strength and elongation of Nb microalloyed steel increase by 41.1 MPa and 2.4%compared with non-Nb microalloyed steel,respectively.