风电塔筒用钢板探伤不合格原因分析与改进

Causes Analysis and Improvement of Disqualified Steel Plate for Wind Power Tower in Flaw Detection

运用酸蚀低倍检验、光学及电子显微分析技术,对某钢厂S355J2+N风电塔筒用钢板探伤不合格原因进行定性分析,并对其影响因素展开讨论。结果表明:钢板心部的微裂纹是此次探伤不合格的主要原因。裂纹的产生,一方面是偏析导致组织应力和轧后冷却过程中形成热应力的共同作用,另一方面是MnS夹杂物偏聚使钢基体界面结合较弱,促进了裂纹的萌生和扩展。通过将钢中硫含量控制在0.003%以内、控制连铸钢水过热度≤20℃、定期和不定期对连铸机扇形段辊缝进行检测、扇形段弧度进行校验以及钢板下线后及时堆垛缓冷等一系列措施,探伤合格率得到有效提升。

By means of acid eching macroexamination,optical and electron microscopic analysis technologies,qualitative analysis is performed on the causes of flaw detection disqualification of S355J2+N steel plate for wind power tower cylinder in a steel plant,the influencing factors of disqualification are also discussed.The results show that the microcrack at the plate center is the major cause of flaw detection disqualification.The crack formation is caused on one hand by the action of structural stress due to segregation and thermal stress during cooling after rolling,on the other hand by crack initiation and propagation due to the poor steel matrix interface binding led by MnS inclusion accumulation.The flaw detection qualification rate is effectively improved by measures of controlling C content in the steel within 0.003% and the superheat of molten steel for continuous casting≤20℃,regularly and irregularly monitoring the roll gap of the caster’s segment,calibrating the segment radian,timely cooling in pile after the steel plate is offline.