不同冷却工艺对冷墩钢小方坯等轴晶率的影响

Study on the effect of different cooling technology on equiaxed grain ratio of cold-heading steel billet

通过改变现场连铸冷却制度,发现一冷、二冷工艺对连铸坯的等轴晶比例具有较大的影响。当结晶器冷却水流量下调后,结晶器内冷却水温差提高,冷却水带走的热量增加,结晶器与铸坯的接触情况及结晶前沿的温度分布得到改善,从而控制了柱状晶的生长,扩大了铸坯中心等轴晶区;二冷水量的改变,更进一步有利等轴晶的生成。采用合理的一冷、二冷工艺可以得到较高等轴晶率的冷墩钢铸坯。对比实验表明:SWRCH8A和SWRCH35K钢铸坯的等晶率均得到了提高。

By studying cooling technique of continuous casting it is found that prtmary cooling and secondary cooling intensity have an important effect on ratio of equiaxed grain of billet. When water rate in mould is decreased both the difference of temperature of inlet and exit cooling water in the mould and the heat carried by cooling water are in- creased and the contact condition between mould and billet and temperature distribution at the solidifying front are improved, thus growth of columnar grain is restrained and ra- tio of equiaxed grain in the center of billet is enlarged. Change of the secondary cooling water intensity is more advantageous to the growth of equiaxed grain. Comparison ex- periments show that ratio of equiaxed grain of SWRCHSA and SWRCH35K steel billet is increased through adopting reasonable primary cooling and secondary cooling technique.