表面剧烈形变与回复处理诱发Q235钢梯度组织结构的力学性能研究

Study on Mechanical Properties of Q235 Steel Containing Gradient Microstructure Induced by Surface Severe Deformation and Recovery Treatment

利用光学显微镜、扫描电镜、能谱仪、X射线衍射仪和拉伸试验机研究了Q235钢表面剧烈压入形变诱发合金化的梯度组织结构对拉伸力学性能的影响。结果表明,采用剧烈压入形变能在低碳钢表面形成具有梯度组织结构的含Cr合金化层,形成的Cr合金化梯度组织的低碳钢拉伸力学性能明显增强,其抗拉强度最大提高约36 MPa,屈服强度最大提高约35 MPa,这是由于表面剧烈形变诱发大量晶体结构缺陷,这些缺陷促进Cr元素扩散,导致CrFe_4固溶增强和(Cr,Fe)_7C_3弥散增强。此外,相邻不同尺度的组织相互作用可提高应变硬化能力,而塑性下降甚微。

The effects of alloying gradient microstrucmre induced by severe punching deformation on the tensile mechanical properties of Q235 steel were investigated by optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and tensile tester. The results show that the gradient structure with Cr alloyed layer on the surface of low-carbon steel can be obtained by severe punching deformation. The tensile properties of low-carbon steel with gradient microstructure with Cr alloyed layer significantly increase, then, the tensile strength increases by about 36 MPa in maximun, and the yield strength increases by about 35 MPa in maximum. Because the surface severe deformation induces a large number of crystal defects, which can promote the diffusion of Cr to form CrFe4 solid solution strengthening and （Cr, Fe）TC3 dispersion strengthening. In addition, The interaction of adjacent and different sizes of microstructure can improve the strain hardening ability, and the drop of plastic is little.