铝对超高碳钢共析转变及先共析碳化物析出行为的影响

Effects of Aluminium Addition on the Behaviour of Pro-eutectoid Carbide Precipitation and Eutectoid Transformation in Ultra-high Carbon Steels

对不同铝含量超高碳钢进行了相平衡热力学计算、热处理工艺试验以及扫描电镜的微观组织观察,研究了铝对超高碳钢平衡共析转变、先共析碳化物的数量和析出行为的影响。结果表明,对超高碳钢进行铝合金化后,平衡共析转变扩展为一个温度区间(A1b^A1e),共析转变的温度下限、上限和共析转变的温度范围均随铝含量的提高而增大;铝合金化使得平衡状态下的先共析碳化物数量减少,从而抑制网状先共析碳化物形成。碳含量低于1.6wt%,添加2wt%以上的铝,可以抑制超高碳钢先共析网状碳化物的形成。在同样的冷却条件下,添加铝使超高碳钢共析体片层间距细化。

The effects of aluminium addition on the precipitation behaviour and amount of pro-eutectoid carbide in ultrahigh carbon steels (UHCs) were investigated by thermodynamics calculation and SEM microstructure analysis. It is shown that there exists a temperature range (A1b-A1e) rather than a definite eutectic transformation temperature for eutectoid transformation in Fe-C binary alloy. Furthermore, both the upper limit (A1e) and the lower limit (A1b) of this temperature range increase with aluminium content in UHCs. The precipitation of pro-eutectoid carbide was inhibited remarkably in UHCs containing less than 1.6% wt carbon by the addition of more than 2%wt Al. The amount of pro-eutectoid carbide in UHCs decreases with the addition of aluminium, especially with greater than 2%wt Al. The lamellar spacing of perlite in UHCs containing aluminium is smaller than that in UHCs free of aluminium.