A study of microstructure and properties of cast Fe-10Cr-1.5B alloy

In the present study, the microstructure and mechanical properties of cast Fe-10Cr-1.5B (FCB) alloy after different heat treatments were studied. The results showed that the as-cast microstructure of FCB alloy consists of alpha-Fe, M(M=Cr, Fe, Mn)(2)(B, C) and M(M=Cr, Fe, Mn)(7)(C, B)(3) type borocarbides, and small amounts of pearlite and austenite. After oil quenching treatment, metal matrix transformed into the martensite from the mixture of martensite, pearlite and austenite. There are many M(M=Cr, Fe, Mn)(23)(C,B)(6) type borocarbide precipitates in the metal matrix, and eutectic borocarbide appears with an apparent disconnection and isolated phenomenon. When the quenching temperature reaches 1,050 degrees C, the hardness of FCB alloy is the highest, but the change of quenching temperature has no obvious effect on impact toughness of FCB alloy. After tempering, the eutectic microstructure of FCB alloy appears with a "two links" trend. With the increase of tempering temperature, the hardness of FCB alloy decreases gradually and impact toughness increases gradually. Cast FCB alloy oil-quenched from 1,050 degrees C and tempered from 200 degrees C has excellent combined properties; its hardness and impact toughness are 61.5 HRC and 8.8 J.cm(-2) respectively.