TD处理中基体成分对覆层影响的热力学分析

Thermodynamics analysis of the influence of substrate elements on coating produced by TD process

基于对45、T8、T10、T12碳素钢和9SiCr、4Cr5MoSiV1及Cr12MoV等合金钢进行了TD处理被覆VC的试验,并用显微硬度计对覆层断面进行金相观察和厚度测量。试验结果表明:对于碳素钢,相同处理条件下的覆层厚度几乎与基体中碳含量成正比;对于合金钢则不成立。根据该试验结果从热力学分析的角度出发探索了合金钢中不同合金元素对TD法被覆碳化物厚度的影响规律。分析表明:合金钢中合金元素的奥氏体碳活度影响因子为正时促进覆层的成长,为负则减缓覆层的成长。

The vanadium carbide coating on various carbon steels and alloyed steels prepared by TD process was investigated. The metallographical structure of cross-section of specimens was observed. The coating thickness of each specimen was measured by micro-sclerometer. The results indicate that the carbon content in carbon steels is nearly linear in relation to the thickness of carbide coating. However, the relation is not suitable for alloyed steels. According to the experiment results, from thermodynamics angle the effect of various alloy elements on the thickness of carbide layer produced by TD process was discussed. The conclusion can be reached that when the austenitic carbon activity influential factor of an alloy element in alloyed steels is positive the alloy element will improve the growth of carbide coating, whereas negative, it will cumber it.