焊接高强钢HG785粗轧开裂原因分析

Roughing cracking analysis of HG785

焊接高强度钢坯在粗轧时开裂,采用金相显微镜和扫描电镜对开裂钢坯进行了观察和分析。结果表明,同批次的钢坯存在中间裂纹和中心等轴晶区的偏移,开裂钢坯的表面和截面均观察到砷富集的现象;分析认为钢坯上下板面冷却速度的不同导致钢坯内部存在较大的内应力,在拉坯时树枝晶间产生中间裂纹,并在粗轧时导致钢坯开裂,而砷富集则导致网状热裂纹的形成。

The sample of the roughing cracking plate was observed and analyzed by means of optical microscope and electron microprobe to find out the causes for the cracking. The results showed there were some cracks in the center and some shift of equiaxed zones, and the phenomenon of arsenic enriched was observed on the surface and the cross section. The observations and analysis concluded that the different cooling rate of the upper and lower plate surface resulted in a large internal stress, which generated a crack between dendrites during casting, and led to cracking in the rough rolling, while the arsenic-rich led to the formation of network cracks.