Non Heat-Treated Vanadium Alloyed Steel Crankshaft

Steel crankshaft is ordinally quench-tempered at forged state, and high frequency induction hardening is performed on it after machining. Authors have developed vanadium alloyed steel crankshaft which requires only air cooling after hot forging instead of the quench-tempering and the induction hardening. The air cooled vanadium alloyed steel had sufficient mechanical properties and wear resistance for crankshafts by precipitation of vanadium carbide or carbo-nitride at cooling process after forging. The difference of air cooled vanadium alloyed steel crankshaft hardness depended on the chemical composition and mass effect, and was satisfactorily small. The following effects were obtained by eliminating the heat-treatment process: 1) Energy savings 2) Decreased process time 3) Decreased distortion 4) Machinability improvement 5) Reduction of total cost