Fe15Mn0.8C-Al-Si热轧轻质高强钢的组织与性能

Microstructure and Mechanical Properties of Hot Rolled Fe15Mn0.8C-Al-Si Light-weight High Strength Steel

对Fe15Mn0.8C-Al-Si热轧试验钢进行1 100℃固溶1 h油冷处理,然后通过金相显微镜、拉伸试验机、X射线衍射仪以及扫描电镜等研究了Fe15Mn0.8C-Al-Si热轧轻质高强钢的组织与性能。结果表明,经过固溶处理后,试验钢的组织由奥氏体(A)和铁素体(δ-F)组成,其中Fe15Mn0.8C8.5Al1.5Si试验钢的奥氏体体积分数最多达到78.9%。三种成分的试验钢在变形过程中均未发生相变,通过层错能的计算结果可推测其变形以位错滑移机制为主。Fe15Mn 0.8C8.5Al1.5Si试验钢的综合力学性能最佳,其断后伸长率达到62.39%,抗拉强度为870.25 MPa,强塑积达到54 294.90 MPa%。Fe15Mn0.8C9.5Al0.5Si、Fe15Mn0.8C8.5Al1.5Si试验钢的断裂方式为韧性断裂,Fe15Mn0.8C7Al3Si试验钢为韧脆混合断裂。

The Fe15Mn0.8C-Al-Si hot-rolled steels were solution treated at 1 100 ℃ for 1 h then cooled in oil. The microstructure and mechanical properties of steels were investigated by using optical microscopy, tensile testing machine, X-ray diffraction （XRD） and scanning electronic microscopy（SEM）. The results showed that the microstructure of the tested steel was composed of austenite（A） and ferrite（δ-F） after solid solution treatment. Especially, the highest volume fraction of austenite of the Fe15Mn0.8C8.5Al1.5Si steel was up to 78%. There was no phase transformation during the deformation of the tested steel, and it was inferred from the SFE calculated results that the deformation was dominated by the dislocation slip mechanism. The Fe15Mn0.8C8.5Al1.5Si steel had the best comprehensive mechanical properties, with the elongation of 62.39%, tensile strength of 870.25 MPa and the product of strength and elongation of 54 294.90 MPa%. The fracture mode of the Fe15Mn0.8C9.5Al0.5Si and Fe15Mn0.8C8.5Al1.5Si steel were ductile fracture, while the Fe15Mn0.8C7Al3Si steel was ductile plus brittle mixed fracture.