夹杂物对管线钢探伤性能的影响及控制

Effect and control of inclusion on the UT property of pipeline steel

利用C-Scan、光学显微镜、扫描电镜等检测手段,对由夹杂物引起的X80管线钢探伤不合缺陷进行分析。结果表明:引起管线钢探伤不合缺陷的夹杂物主要有两类,一类是细小夹杂物聚集成的团簇状夹杂,一类是大尺寸的长条状夹杂物,局部伴有大颗粒状或块状夹杂。通过优化钙处理工艺,使钢水中Al2O3夹杂物均改性为低熔点铝酸钙夹杂,延长浇铸前钢水的镇静时间促使夹杂物充分上浮,夹杂物引起的探伤不合率由5.4%降低至0.31%,提高了产品质量。

By using C-Scan,optical microscopy and scanning electron microscopy,X80 steel plates defects were analyzed to investigate the effect of inclusion on ultrasonic testing property.The results showed that the poor UT property was caused by two types of inclusions,one was clusters of small-sized inclusions,the other was large-sized lath-shape inclusions,locally accompanied by large granular or massive inclusions.By optimizing the calcium treatment process,Al2O3 inclusions were modified into calcium aluminates with low melting point,and the time before casting was extended as well to promote the removal of inclusions.Thus,the UT property was improved significantly,with a failure rate decreasing from 5.4%to 0.31%.