含硼氮中碳铝镇定钢中BN夹杂析出热力学分析

Thermodynamic analysis of BN inclusion precipitation in medium-carbon aluminum killed steel containing B and N

运用数值模拟方法对含硼氮中碳铝镇定钢中BN 析出的热力学条件进行分析,研究该钢种在冶炼浇注及加热奥氏体化过程中BN夹杂物的析出规律,并与试验情况进行了比较.结果表明,在钢液中初始ω（B）≤0.012%、初始w（N）≤0.03%的情况下,含硼氮中碳铝镇定钢浇注凝固过程中不能析出BN夹杂物,且钢液中B的富集程度远高于N,凝固末期残余液相中,B浓度是其初始浓度的20倍,N 浓度约为其初始浓度的2.1倍;钢中ω（B）为0.005%-0.01%、ω（N）为0.01%-0.03%时,在1470K奥氏体化温度以下,可以稳定析出BN夹杂物,B、N含量越高,BN夹杂开始析出的温度越高;在奥氏体化过程中,钢坯中酸溶铝含量越高,越容易析出BN夹杂物.

In order to invesitigate the precipitation law of BN inclusion in medium‐carbon Al‐killed steel containing B and N ,thermodynamic conditions of BN precipitation in the casting and austenitizing process was analyzed by numerical modeling method ,whose results were compared with actual exper‐iment results .It shows that BN does not precipitate during solidification when initial [B] and [N] contents are not more than 0 .012% and 0 .030% ,respectively ,in the liquid steel .In addition ,the en‐richment degree of B in the molten steel is far higher than that of N .At the end of solidification ,B and N concentrations are about 20 ,2 .1 times as high as that of their initial concentrations in remnant liquid steel .BN inclusions can steadily precipitate when [B ] and [N ] contents are in the range of 0 .005% ~0 .01% ,0 .01% ~0 .03% ,respectively .BN can precipitate below the austenitizing tempera‐ture of 1470 K .The greater [B] ,[N] contents are ,the higher initial precipitation temperature of BN inclusion will be .With the increase of Als content in steel ,the precipitation of BN inclusion becomes easier in the austenitizing process .