某公司生产的硼微合金化钢铸坯表面出现了严重的横裂纹。采用宏观观察、化学成分分析、金相检验、扫描电镜及能谱分析、热塑性分析等方法研究了该铸坯裂纹产生的原因。结果表明:铸坯的碳元素含量过高、铸坯的二次冷却制度不合理、铸机拉坯速率较低及铸机设备精度控制不当等因素导致铸坯表面产生横裂纹。采用优化原材料化学成分、提高拉坯速率、控制铸机精度等方法可以避免铸坯产生横裂纹。

Severe transverse cracks had appeared on the surface of boron microalloyed steel billets produced by a certain company. The reasons for the formation of cracks in the billet were studied by macroscopic observation, chemical composition analysis, metallographic examination, scanning electron microscopy and energy spectrum analysis, and thermoplastic analysis. The results show that factors such as excessive carbon content in the billet, unreasonable secondary cooling system, low casting rate of the casting machine and improper precision control of the casting machine equipment had resulted in transverse cracks on the surface of the billet. Adopting methods such as optimizing the chemical composition of raw materials, improving the casting rate and controlling the accuracy of the casting machine could avoid transverse cracks in the casting billet.