钒对钢轨钢机械性能的影响及其机理

Investigation of the Effect of Vanadium on the Mechanical Properties and its Mechanism of Rail Steel

Cr-V轨钢是一种高强度轨钢,与晋碳轨钢相比,其强度硬度提高,塑性韧性下降,特别是疲劳裂纹扩展和断裂性能下降。本文通过两种钢显微组织参数的测定及透射电镜观察,结果表明:含钒轨钢中VC沉淀使钢的强度提高,但韧性下降。其原因可能与铁素体内和铁素体与渗碳体界面上的碳化钒沉淀有关,该沉淀物与基体保持某种共格关系,且成线状分布,并平行于基体的解理面。如使沉淀物长大并脱离共格关系,可使轨钢的韧性有较大提高。

The Cr-V rail steel is a high-strength steel, its strength and hardness are higher than those of the standard carbon rail steel, but the ductility and toughness are lower than those of the latter one. In this paper ther their microstructures were examined by optical and electron microscopy, and the prior austenite grain size, Dr, the pearlite interlamellar spacing, Sm, and the pearlite colony size, Dc, were determined. The distribution of precipitates was also observed. The experimental results show that the low ductility of the Cr-V steel may be attributed to the effects of rows of coherent vanadum carbide precipitates within the ferrite, as well as in boundary are as between ferrite and cementite. It has been found that the growth of carbide precipitates van increase the toughness of the Cr-V steel.