Induction-quenched trace alloy steel with high fatigue strength properties

摘要

PCT No. PCT/US97/11386 Sec. 371 Date Sep. 16, 1997 Sec. 102(e) Date Sep. 16, 1997 PCT Filed Jul. 1, 1997 PCT Pub. No. WO98/00570 PCT Pub. Date Jan. 8, 1998Improved fatigue strength properties are achieved in an induction hardened microalloy steel useful for demanding service environments. The microalloy steel has low carbon and sulfur contents, comprising in % by weight, 0.15% to 0.45% C, 0.50% to 1.60% Mn, up to 0.20% V, 0.0001% to 0.01% S, balance Fe. The material is fabricated to a selected configuration, such as an engine crankshaft, for example. Selected surfaces of the fabricated article are hardened by induction heating. The article can be used directly after induction hardening or it may be tempered at low to moderate temperatures of from about 100 DEG C. (200 DEG F.) to 290 DEG C. (550 DEG F.) to achieve a desired surface hardness and compressive residual stress level. The controlled alloy chemistry and low tempering temperature provide a substantial increase in bending fatigue strength over conventional higher carbon grade steels.