45钢热轧板锯切开裂原因分析

Analysis of reasons for sawing cracking of 45 steel hot-rolled plate

针对某钢铁企业生产的45钢热轧板锯切开裂问题,分析了开裂钢板的化学成分,利用光学显微镜、扫描电镜对热轧板裂纹源的形貌和金相组织进行了检测,并将检测结果与生产数据进行了比较和验证。结果表明:由于连铸机扇形段辊缝精度不达标,铸坯形成严重的中心偏析和中心疏松,致使成品钢板1/2处产生严重的珠光体偏析,心部较正常部位强度、硬度高,塑性低,组织应力聚集在疏松空洞边缘,无法有效释放,形成锯切开裂的驱动力。夹杂物以及粗大的晶粒加剧开裂的趋势。上述原因综合作用导致45钢热轧板锯切开裂。

Aiming at the sawing cracking problem of 45 steel hot rolled plate produced by an iron and steel enterprise, the chemical composition of the cracked steel plate is analyzed, the morphology and metallographic structure of the cracking source of hot rolled plate were detected by optical microscope and scanning electron microscope, and the detection results were compared and verified with production data.The results showed that:Because the roll gap accuracy in the sector section of the continuous caster was not up to the standard,and the casting billet formed serious central segregation and central porosity, resulting in serious pearlite segregation at 1/2 of the plate,the strength and hardness of the core were higher than other part of the plate, and the plasticity of the core is lower than other part of the plate, the tissue stress is concentrated at the edge of the loose cavity and cannot be effectively released, which formed the driving force of cracking during sawing. The coarse grain and the inclusion aggravated the cracking trend. The combined effect of the above causes caused sawing cracking of 45 steel hot-rolled plate.