压力容器用钢表面裂纹分析与控制

Cracking analysis and control measures for pressure vessel steel

针对压力容器用钢表面出现星状裂纹现象,通过金相显微镜、扫描电镜、电子探针对压力容器用钢表面裂纹进行宏观形貌、化学成分、元素偏析、夹杂物分析。结果表明:表面裂纹产生的主要原因是结晶器铜板磨损破裂,导致Cu和Ni溶入钢液,使晶界脆化,产生热脆现象,形成裂纹源。同时,裂纹内部大颗粒高熔点夹杂物的存在,保护渣选择不合适,也是裂纹源形成原因之一。为此,在实际生产中,对连铸工艺进行严格控制,防止此类缺陷产生。

Surface cracks of pressure vessel steel were observed and analyzed by optical microscope,scanning electron microscopy and electron probe. The results indicate that the main reason is the wear of mould copper plate,resulting in solving of Cu and Ni into the liquid steel,enabling grain boundary embrittlement and hot short phenomenon,then forming crack sources. At the same time,large inclusion particles introduced by inappropriate protecting slag are also the causes of the cracks in the casting slab. Combining with production practice,continuous casting process control measures were discussed to prevent the formation of crack defects.