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对两种低合金铸钢的沿晶脆性断裂现象进行了研究,结果表明,两种脆化材料的断口均为沿晶脆性断裂。在沿晶面上观察到生长完善的枝晶结构和疏松露头。透射电镜观察与电子衍射分析确认,有薄膜状第二相沿晶间和枝晶沉淀。用俄歇电子能谱仪和离子探针测定了脆性断裂面上杂质元素的偏析,结果表明,沿晶表面上存在H,C,O,N和S的偏析,尤其以O的偏析为甚。经冶炼工艺试验证实,引起两种铸钢的晶间脆性的主要原因是AlN沿初生奥氏体晶界和枝晶间的沉淀,而H,O,N,C等杂质元素的偏聚促进了这种脆性现象的发生。
The phenomenon of brittle fracture along two grains of low alloyed steel was studied. The results show that the fracture of both brittle materials are along the brittle fracture. The well-developed dendrite structure and loose outcrops were observed along the crystal plane. Transmission electron microscopy and electron diffraction analysis confirmed that there was a thin film-like second phase along the intergranular and dendrite precipitation. The segregation of impurity elements on the brittle fracture surface was measured by Auger electron spectroscopy and ion probe. The results show that there are segregation of H, C, O, N and S along the crystal surface, especially the segregation of O. The smelting process test confirmed that the main reason for the intergranular brittleness of the two castings is the precipitation of AlN along the grain boundaries and dendrites of the primary austenite, which is facilitated by the segregation of H, O, N, C and other impurity elements The occurrence of brittle phenomenon.