铝元素抑制超高碳钢中网状碳化物析出机理

借助相图计算、能谱分析及组织观察研究了铝元素对超高碳钢中网状碳化物析出过程的影响，含碳1．5wt％的超高碳钢添加不同含量的铝后显著影响网状碳化物的析出：随铝含量增加，奥氏体晶粒尺寸愈小、晶界愈多，导致网状碳化物减薄；未溶碳化物愈多、奥氏体固溶碳含量愈少，导致网状碳化物析出量减少；晶界聚集铝量增加，聚集的铝抑制碳化物的形核及长大。当铝含量接近2．0wt％时，网状碳化物出现断续，甚至有的晶界没有碳化物析出，在球化过程中，该网状碳化物很容易球化。

Mechanism of Network Carbide Precipitation Inhibited by Aluminum in Ultra-High Carbon Steel

The influence of Al on the separation of netlike carbide in the Ultra High Carbon Steel (UHCS) is investigated by CAPHAD, EDS analysis and microstructural observation. It is found that the Al content strongly influences the separation of netlike carbide in the UHCS with 1.5wt%C. With Al increasing, the Austenite grain size decreases and the amount of grain boundary increases, thus the forming of netlike carbide is restrained. The undissolved carbide increases, the carbon dissolved in austenite decreases, thus the driving force for the separation of netlike carbide becomes less. The enrichment of Al around the grain boundaries also retards the nucleation and growth of netlike carbides. When the Al content approaches 2.0wt%, the network carbide tends to be discontinues, and even no carbide is observed in some grain boundaries, this kind of netlike carbide is easy to be spheroidized during spheroidizing.