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利用光学显微镜、扫描电子显微镜、能谱仪、X射线衍射仪、显微硬度计研究剧烈形变和低温回复处理对低碳钢表面Cr合金化的梯度组织结构和力学性能的影响。结果表明,采用机械剧烈冲击形变和低温回复处理能够在低碳钢表面形成具有梯度组织结构的含Cr合金化层,含Cr相主要为Fe-Cr固溶体和碳化物(Cr,Fe)_7C_3,且硬度从心部145 HV1逐渐向表层提高到215 HV1,这是由于应力增加导致晶体结构缺陷增多,同时应力引起温度升高以及后续的低温回复热处理过程中,在应力-热耦合效应的共同作用下,Cr元素扩散系数增加,加速扩散,促进合金化,形成梯度组织结构,显著改善和提高原材料的组织和力学性能。
The effects of severe deformation and low temperature recuperation on the gradient structure and mechanical properties of Cr alloying on mild steel were investigated by optical microscopy, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction and microhardness tester. The results show that Cr-containing alloying layer with gradient structure can be formed on the surface of low carbon steel by mechanical severe impact deformation and low temperature recuperation. The main phase containing Cr is Fe-Cr solid solution and carbide (Cr, Fe) _7C_3, and Hardness increases gradually from core 145 HV1 to surface 215 HV1 due to the increase of stress resulting in the increase of crystal structure defects and stress induced temperature rise and subsequent low temperature recovery heat treatment under the combined effect of stress-thermal coupling , Cr element diffusion coefficient increases, accelerate diffusion, promote alloying, the formation of gradient organizational structure, significantly improve and improve the raw material of the organization and mechanical properties.