Mechanical and wear behavior of alloyed gray cast iron in the quenched and tempered and austempered conditions

Three groups of hypereutectic cast irons alloyed with Cu, Ni and microalloying additive like Ti and Nb were examined for its hardness and wear resistance in the austempered (360 °C/3 h) and quenched and tempered conditions at varying tempering temperatures. It is observed that the cast irons in the quenched and tempered condition showed good wear resistance and moderate hardness at 400 °C. This was comparable with the wear resistance in austempered condition. The study also showed that in quenched and tempered condition, increasing Cu content in cast irons improved its wear resistance moderately while increasing Ni content has decreased its wear resistance. The presence of strong carbide formers (Nb, Ti) did not give significant improvement in wear resistance in quenched and tempered condition. Even in austempered alloys, higher Cu content increases its wear resistance and higher Ni content decreases their wear resistance. The austempered alloys showed ausferritic microstructure with 20% austenite phase which enhances wear resistance through transformation induced plasticity effect. On the other hand, the quenched and tempered alloys showed good wear resistance at 400 °C due to fine tempered carbides in the matrix.

► Alloyed cast irons were austempered at 360 °C and also oil quenched and tempered at 100 to 600 °C. ► Hardness shows declining trend with increase in tempering temperature. ► Wear loss of quenched and tempered cast irons shows small maxima between 100 and 400 °C. ► Wear resistance of quenched and tempered and austempered cast irons were comparable till 400 °C.