车轮钢大型夹杂形成机理研究

通过冷态试验，提出车轮钢中大型夹杂物的形成机理，一是浇注前期钢水从直孔型模底砖冲入模内后，会在中心液面上形成峰涌现象，将浮在液面上的大型夹杂物推向钢锭四周的凝固前沿，造成钢锭四周大型夹杂物富集带。另一是浇注后期，钢锭液面由于散热温度降低，钢水会依托浮在液面的大型夹杂物进行非均质形核、凝固，当包裹着大型夹杂物的凝固层达到一定的体积后，其比重大于钢水的比重时，就会沉入锭底，形成沉积锥大型夹杂物分布带。本文根据大型夹杂物形成机理，在生产中采取了相应的改进措施，使夹杂废品率由５．０７％降到２．０５％，下降了５０．６９％。

Research on the forming mechanism of large inclusions in wheel steel

By the cold test, two Points are given about the forming mechanism of large inclusions in wheel steel. one is that the large inclusions floated on level are pusher to the solidifying front around the side of ingot because of the rising phenomenon formed in center of liquid level, during earlier pouring stage. The other is that the non - uniform nucleation and solidification of molten steel are made to rely on the large inclusions floated on level, and this mixture solid is fell to the bottom because of its heavier gravity, and the large inclusions distribution zone are formed during later pouring stage. Based on two forming mechanisms of large inclusions, the improved measures are taken in industrial test. Result shows the inclusion waste rate is reduced to 2. 5 % from 5. 07%.