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对有缺陷45铸钢件的初步分析查明了韧性断口表面的晶间缺口,会引起应力集中,降低了显微塑性变形和提高了金属的脆性断裂倾向。随着上述缺陷的数量,尺寸和在层内深度的增加,铸件中的疲劳裂纹数量亦增加,这样便会降低零件的寿命。因此研究了铸件中晶间缺口的形成机理并拟制了消除它的措施。显微光谱分析查明在晶间缺口表面集聚Si,其浓度要超过它在铸钢中平均含量的6～8倍。同时其他化学元素不出现偏析,这可认为晶间缺口属于吸附的夹层,主要由Si的氧化物组成。这一点可由该金属试样的电解质溶液中析出的非金属夹杂物的沉淀物得到证实,沉淀物的基质系由折射指数为1.46的透明硅酸盐矿物组成,这相当于纯的二氧化硅。某些硅酸盐矿
A preliminary analysis of the defective 45 cast steel found that the intergranular gap in the ductile fracture surface caused stress concentration, reduced the microplastic deformation and increased the brittle fracture tendency of the metal. With the above number of defects, size and depth of the layer increases, the number of fatigue cracks in the castings also increase, which will reduce the life of the parts. Therefore, the formation mechanism of intergranular gap in castings was studied and the measures to eliminate it were proposed. Micro-spectroscopic analysis revealed that the concentration of Si at the intergranular gap surface exceeded the average concentration of Si in the cast steel by 6 to 8 times. At the same time, other chemical elements do not appear segregation, which can be considered intergranular gap belongs to the adsorbed interlayer, mainly composed of Si oxide. This is evidenced by the precipitation of non-metallic inclusions precipitated from the electrolyte solution of the metal sample, the matrix of the precipitate consisting of a transparent silicate mineral having a refractive index of 1.46, which corresponds to pure silica. Some silicate ore