YQ450NQR1高强耐候钢表面裂纹成因分析  

Analysis of reasons for surface cracks of high strength weathering steel YQ450NQR1

作　　者：王雷[1] 卿家胜[1,2] 窦坤[1] 张晓峰[1] 王宝[1] 黄运华[3] 刘青[1] 

机构地区：[1]北京科技大学钢铁冶金新技术国家重点实验室,北京100083 [2]攀钢集团西昌钢钒有限公司,四川西昌615000 [3]北京科技大学新材料技术研究院,北京100083

出　　处：《炼钢》2015年第4期72-78,共7页Steelmaking

基　　金：钢铁冶金新技术国家重点实验室自主研发基金(41602023);国家自然科学基金(51074023)

摘　　要：针对火车车厢中梁用钢YQ450NQR1高强耐候钢的腿部拉裂问题，运用金相显微镜、扫描电镜和能谱仪对拉裂裂纹形貌进行分析；设计裂纹脱碳模拟试验，探明裂纹两侧发生脱碳的工艺条件并判定裂纹产生工序；通过对铸坯原料进行低倍检测明确与拉裂相对应的连铸坯质量缺陷，并结合检测结果对铸坯缺陷产生原因进行分析。研究结果表明，腿部拉裂缺陷是由严重的铸坯边部皮下网状裂纹造成的，而钢水在结晶器中冷却不均匀、残余元素含量高以及氮含量波动范围过大是造成皮下网状裂纹的主要原因。通过采取措施，YQ450NQR1钢腿部拉裂率由原来的0．5％～3．5％稳定控制在1％以下。For crack problem on legs of high strength weathering steel YQ450NQR1 used for train center sill, the morphology of surface cracks was analyzed by the use of optical microscopy, scanning electron microscopy （SEM） and energy disperse spectros- copy （EDS）. The conditions for decarburization of crack sides were investigated by the design of decarburization simulation experiments to determine formation process of cracks. The quality defects of YQ450NQR1 bloom, corresponding to cracks on legs, were identified by macroscopic examination and the causes for subcutaneous net cracks were analyzed based on the test results. The results showed that the crack defects on legs of high strength weathering steel YQ450NQR1 were caused by serious subcutane- ous net cracks at the edge of bloom and uneven cooling of molten steel in mold, high lev- el of residual elements as well as big fluctuations of nitrogen content contributed to the formation of subcutaneous net cracks. The occurrence ratio of cracks on legs of YQ450NQR1 steel, which fluctuated between below 1% after some measures were taken. 0.5 %-3.5 % originally, was stabilized

关 键 词：YQ450NQR1钢 连铸坯 脱碳 网状裂纹 铜 析出物 

分 类 号：TF777.2[冶金工程—钢铁冶金]