Effect of Vanadium Content on Microstructure of High-carbon Pearlitic Steels at Different Cooling Rates

The microstructure changing of SWRS82B wire rod steel with vanadium microalloying after air-cooling at different cooling rates and salt bath cooling were invistigated. The results show that vanadium refined the austenite grains in SWRS82B wire rod steel. When the vanadium content was more than 0.16wt%, ferrites along crystal boundary grew obviously after air-cooling below 16 ℃·s-1. When the vanadium content was less than 0.08wt%, and the air-cooled rate was between 10-16 ℃·s-1, the ferrites did not apperared in the specmens. Vanadium element encouraged the segregation of carbide along grain boundary, and the formation of carbon-poor zone in some areas promoted the appearance of ferrite. And by addition of vanadium element the eutectoid point of high carbon steel moved to the right, which enlarged the area of pro-eutectoid ferrite.