摘要
针对X65管线钢探伤不合缺陷,从夹杂物转变过程分析了缺陷产生的原因,并提出了合理的钙处理工艺,达到控制B类夹杂物、降低探伤不合发生率的目的。研究结果表明,原工艺冶炼过程中夹杂物的转变过程为Al2O3→MgO-Al2O3→MgO-Al2O3-CaO→CaO-Al2O3,且最终夹杂物主要为低熔点区的高CaO质量分数钙铝酸盐;通过热力学计算,针对管线钢夹杂物控制提出了新的夹杂物控制目标,并建立了钙处理模型,根据实际的钢液条件计算钙处理控制窗口,用于指导不同w([S])、w(T[O])条件下的合理喂钙量。通过优化处理工艺,钢中钙质量分数由原工艺的0.0030%~0.0040%降低至0.0010%~0.0020%,铸坯中夹杂物类型为MgO-Al2O3-(CaO)-CaS低熔点和高熔点相复合的夹杂物,B类夹杂不大于2.0的一检合格率由96.5%提高至97.5%,夹杂物引起的探伤不合格率由10.0%降至1.5%以下,提高了管线钢的产品质量。
The cause of nonconformity in flaw detection of X65 pipeline steel was determined by analyzing the process of inclusions transformation.Meanwhile,a reasonable calcium treatment process was proposed to control B type inclusions and reduce the rate of flaw detection.The results show that the transformation process of inclusions in primary process was Al2O3→MgO-Al2O3→MgO-Al2O3-CaO→CaO-Al2O3.And final inclusions were mainly calcium aluminate containing high mass percent of CaO in the low melting point area.Inclusion control target in the pipeline steel was proposed by the thermodynamic calculation and a model of the calcium treatment of the molten steel was established.According to the actual condition of molten steel,the reasonable calcium treatment control window was calculated to guide the practical production under the condition of different S and T[O] mass percent,by optimizing the treatment process,the mass percent of calcium in molten steel was reduced from 0.003 0%-0.004 0% to 0.001 0%-0.002 0% for the original process.The type of inclusions was consist of MgO-Al2O3-(CaO)-CaS including the low melting point and the high melting point phase composites.The first pass percent of severity of B inclusions≤2.0 was enhanced to 97.5% from 96.5%.The rate of nonconformity in the flaw detection was reduced from 10.0% to 1.5% and the quality of pipeline steel was improved remarkably.
作者
刘延强
张鹏
何文远
杨晓山
黄财德
赵长亮
LIU Yan-qiang;ZHANG Peng;HE Wen-yuan;YANG Xiao-shan;HUANG Cai-de;ZHAO Chang-liang(Steelmaking Department , Shougang Jingtang United Iron and Steel Co., Ltd., Tangshan 063200, Hebei, China)
出处
《钢铁》
CAS
CSCD
北大核心
2018年第12期44-53,93,共11页
Iron and Steel
关键词
管线钢
B类夹杂物
二次精炼
钙处理
pipeline steel
B type inclusion
secondary refining
Ca treatment
