限制淬透性钢的组织与应力状况的研究

Study on Microstructure and Residual Stress in the Limited Hardenability Steel

对穿透感应加热淬火后的限制淬透性钢制的轴承实物进行了系列实验和检测。结果表明：从试样表面至３２０ｍｍ深度均存在压应力，在裂纹源附近存在较大残余压应力的加强作用。淬硬层的基体组织主要为板条马氏体，马氏体含碳量经估测略高于０４％，有较好的韧性。基体上有弥散分布的碳化物Ｍｅ３Ｃ型（Ｍｅ为ＦｅｘＣｒｙＭｎｚ）。心部组织为托氏体。淬硬层中残余奥氏体量仅为５％左右，对应于较高的尺寸稳定性。在上述诸因素综合作用下使材料得以强韧化。

A series of measurements were taken in the limited hardenability bearing rings.Experimental results showed several features which strengthened the rings in the follows:there existed compressive residual stress from surface to the depth of 3.2 mm and larger compressive stress at the position of fatigue fracture source;the matrix of the hardened layer was mainly composed of lath mastensite with dispersedly distributed carbides,the carbon content of martensite was estimated to be a little higher than 0.4%;the structure of core is troosite, the amount of retained austenite in the surface layer was about 5% which ensures the high size stability of bearing.