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本文主要采用X射线法对激光相变硬化处理后试样表面至内部的残余应力进行逐层测定。并辅以小孔应力释放法予以比较。结果表明:在通常激光相变硬化处理参数下,碳钢的残余应力按正弦波规津分布。表面为压应力,内部为拉应力。其幅值随激光参数减小而减小。二次激光相变硬化处理的残余应力为拉应力。本文对残余应力在激光相变硬化处理热循环过程中的形成进行了解释。在最初升温阶段,表面发生热塑性变形而形成少量压应变。在随后的冷却过程中产生拉应变。当发生奥氏体向马氏体组织转变时,又产生压应变。因此,最终残余应力状态是表面达到的温度,塑性屈服量,组织转变量等因素综合影响的结果。而与是终形成的组织,残余奥氏体量等没有对应关系。
In this paper, X-ray method is mainly used to measure the residual stress from the surface to the inside of the sample after laser phase transformation hardening. And supplemented by small hole stress relief method to be compared. The results show that the residual stress of carbon steel is distributed in the form of sine wave with the parameters of laser phase transformation hardening. The surface of the compressive stress, the internal tensile stress. Its amplitude decreases with decreasing laser parameters. The residual stress of secondary laser phase transformation hardening treatment is tensile stress. In this paper, the formation of residual stress during thermal cycling of laser phase transformation hardening process is explained. In the initial heating stage, the surface of the thermoplastic deformation occurs to form a small amount of compressive strain. Tensile strain is generated during the subsequent cooling. When austenite changes to martensite, compressive strain is generated. Therefore, the final residual stress state is the result of the combined effects of surface temperature, plastic yield, and the amount of tissue transformation. And the final formation of the organization, the amount of retained austenite, etc. There is no correspondence.