热轧带钢表面横裂纹原因分析

Surface transverse crack analysis of hot rolled strip steel

某一时间段内热轧带钢表面横裂纹缺陷频发,严重地影响了产品的质量。通过显微组织和生产实际分析,发现高压除鳞水异常返水,造成中间坯表面局部过冷,温差引起内应力过大,产生表面微裂纹。局部过冷区域提前发生奥氏体向铁素体转变,因铁素体组织较奥氏体组织塑性差,导致轧制过程中使微裂纹进一步拓展成裂纹。

In a certain period of time,the surface transverse cracks of hot rolled strip occur frequently,which seriously affects the quality of products.Through the analysis of microstructure and production practice,it is found that the abnormal return of high-pressure descaling water causes local supercooling of the surface of the intermediate billet,and the temperature difference causes excessive internal stress,resulting in surface microcracks.The austenite to ferrite transition occurred in the local supercooled area ahead of time.Because the ferrite structure is less plastic than the austenite structure,the micro-cracks further expanded into cracks during the rolling process.