Microstructures and Mechanical Properties of Austempered Fe-C-Si-B Alloy

AbstractA new type of Fe-C-Si-B alloy was developed. The investigation on microstructure details and the mechanical properties were performed for different austempering combinations. The results indicated that the Fe-C-Si-B alloy comprises ferrite, pearlite and interdendritic eutectic borides in as-cast condition. The distribution of eutectic boride with a chemical formula of M2B (M represents Cr, Fe, Mn or Mo) and is much like that of carbide in high chromium white cast iron. Pure ausferrite structure that is consisted of bainitic ferrite and carbon-riched retained austenite can be obtained by austempering treatment to the Fe-C-Si-B alloy. No carbide would precipitate in the structure and there is not any morphology change of borides. The hardness of the Fe-C-Si-B alloy decreases with increasing of the austempering temperature, and decreases greatly in at the early stages (within 5 to 10 min) of austempering transformation. The transformation is almost finished after about 5 to 10 min when thehardness of the alloy does not change anymore. The Fe-C-Si-B alloy is a new kind of wear resistance material with bright application prospect