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对E550探伤不合格试样进行了分析,发现探伤不合格是由于连铸卷渣引起。但在保护渣与钢基的结合处存在厚度为200~300μm的纯铁素体带异常组织。应用光学显微镜、电子探针等对缺陷周围的异常组织进行了详细探讨。结果表明:探伤不合格是由于连铸卷渣引起;保护渣周围的异常组织是由于保护渣中存在非晶态的Si O2,在钢液凝固时硅扩散到钢中形成富硅区域,导致钢从液态直接进入α相区,形成只有铁素体+极少量珠光体组织,而不是回火索氏体组织。
The E550 flaw detection failed samples were analyzed and found that failed testing is due to continuous casting slag caused. However, there is an abnormal structure of pure ferrite with a thickness of 200-300 μm at the junction of the mold powder and the steel base. The application of optical microscope, electron probe and other defects around the organization were discussed in detail. The results show that the unqualified flaw is caused by the continuous casting slag entrapment. The abnormal structure around the flux is due to the amorphous Si O2 in the flux, which diffuses into the steel to form the silicon-rich region during solidification of the molten steel, Directly from the liquid into the α-phase region, the formation of only a small amount of ferrite + pearlite, rather than tempered sorbite.