抗氢致开裂管线钢尾坯洁净度分析

为了研究抗酸管线钢尾坯洁净度影响因素，试验分析结果发现，中间包留钢量在5和18 t时，尾坯TO质量分数分别为0.004 5%和0.002 0%，拉速在0.8～1.5 m/min时，拉速变化对尾坯平均TO质量分数影响不大；而拉速在1.5～1.8 m/min时，随拉速变大，尾坯平均TO质量分数明显变大。通过制定可行措施取得一定效果，先停浇尾坯和后停浇尾坯前10.7 m的TO质量分数为0.001 2%～0.002 2%，平均氮质量分数为0.002 6%，两块尾坯的碳、硫质量分数波动很小，完全满足抗氢致开裂(HIC)管线钢要求。ASPEX夹杂物分析结果表明，先停浇尾坯边部、中心每平方毫米上直径不小于0.64 μm的夹杂物个数波动范围分别为8～16和7～13，后停浇尾坯边部、中心分别为8～15和8～17。

Cleanliness analysis of last slab of HIC resistance pipeline steel

In order to study the factors affecting the cleanliness of tailings of acid resistant pipeline steel, the test analysis showed that when the amount of steel remaining in the tundish was 5 and 18 t, the TO mass fraction of the last slab were 0.004 5% and 0.002 0%, respectively. When the casting speed was in the range of 0.8 1.5 m/min, the variation of the casting speed had little effect on the average TO mass fraction of slab, while when the casting speed was 1.5 1.8 m/min, the average TO content of the last slab increased obviously with the increase of casting speed. After the application of the related measures in actual production, the control effect of the last slab cleanliness was that for the first 10.7 m of the last slab for the first stop and the last stop, the highest TO mass fraction was 0.002 2%, and the lowest mass fraction was 0.001 2%, the average N mass fraction was 0.002 6%. And the fluctuation of C and S mass fraction fluctuations of the two last slabs were both small, which fully met the requirements of the HIC resistance pipeline steel. The inclusion analysis results obtained by ASPEX indicated that the number of inclusions with the diameter greater than 0.64 μm every square millimeter was 8 16 and 7 13 at the edge and center of the last slab for the first stop, and 8 15 and 8 17 at the edge and center of the last slab for the last stop, respectively.