厚规格高Nb成分X80M管线钢探伤不合原因分析及改进措施

Cause analysis and improvement measures on UT failure of thick gauge X80M pipeline steel plate with high Nb content

针对集中出现的厚规格高Nb成分X80M管线钢探伤不合问题,利用光学显微镜、扫描电镜及能谱仪等检测手段,对钢板缺陷处进行检测分析。结果表明:钢板中心富集的铌、钛夹杂物是导致探伤不合的直接原因,而冶炼中LF精炼过程温度低,净空小,钢水加热及搅拌效果差,致使加入的铌铁未完全溶解或溶解的铌分散不均匀,是导致探伤不合问题的根本原因。

Aiming at the nonconformity in flaw detection of thick gauge X80M pipeline steel with high Nb content, the defecting and inclusion analyses are carried out by approaches such as optical microscopy,scanning electron microscopy and energy spectrometey. The results show that the niobium and titanium inclusions enriched in the center of the steel plate are the direct causes of the nonconformation, while the fundamental causes of the nonconformation are the low temperature, small clearance and poor heating and stirring effect of molten steel in the LF refining process, resulting in the incomplete dissolution of added ferroniobium or the uneven dispersion of dissolved niobium.