热送裂纹产生机制及生产工艺控制研究

针对包钢宽厚板铸坯热装热送生产工艺产生的钢板细小纵向裂纹进行了金相取样分析，确定了缺陷为轧制工艺之前产生。产生原因是热送的高温铸坯表面在加热炉内产生了混晶组织，降低了晶界塑性，裂纹初步产生于加热过程，并在后续的轧制过程中扩展。采用自主设计的红送铸坯表面淬火处理装置使铸坯表面温度降低至650 ℃以下，有效改善了铸坯的表层组织、提高了铸坯表面的综合力学性能，避免了热送裂纹的产生。包钢宽厚板铸坯热装热送比例由试验初期月平均30%提升至最高72%的水平，显著降低了产线的制造成本，缩短了供货周期 。

The mechanism and control measures research of hot charging crack

Metallographic specimens were taken and analyzed from wide and heavy plate with small longitudinal cracks produced in hot charging and hot transferring process from Baotou Steel，and the results prove that defects have occur before hot rolling process. The mixed crystal structure appearing on the surface of high temperature slab in the heating furnace decreased plasticity of the grain boundary，so cracks occurred during the heating process and expand in the hot rolling process. After self-designed surface quenching devices were applied，surface temperature of hot transportation slab could be reduced to less than 650 ℃，the slab surface microstructure and integrated mechanical property were effectively improved，and crack initiation was avoided in hot transferring process. Ratio of wide and heavy plate adopting hot transferring process has increased from 30% at the beginning of the trial to 72%，consequently the manufacturing cost of production line could significantly decrease，delivery time was shorten and considerable economic benefits were brought to the enterprise.