Induction hardened microalloy steel having enhanced fatigue strength properties

A steel article having a composition consisting essentially of the following constituents in % by weight:

• 0.15 to 0.45 carbon (C);
• 0.50 to 1.60 manganese (Mn);
• 0.0 to 0.20 vanadium (V);
• 0.001 to 0.10 sulfur (S) and balance essentially iron (Fe);
• and
• said steel article having at least one induction hardened surface.

A method of making a steel article resistant to bending fatigue comprising the steps of:

• a) providing a steel having a composition consisting essentially of, in % by weight:
• 0.20 to 0.35 C,
• 1.00 to 1.50 Mn,
• 0.05 to 0.15 V,
• 0.001 to 0.06 S,
• balance essentially Fe;
• and
• b) induction hardening selected surfaces of the steel article.

A steel article resistant to bending fatigue having a composition consisting essentially of the following constituents in % by weight:

• 0.20 to 0.35 carbon (C);
• 1.00 to 1.50 manganese (Mn);
• 0.05 to 0.15 vanadium (V);
• 0.001 to 0.008 sulfur (S) and balance essentially iron (Fe);
• and
• said steel article having at least one induction hardened surface.

A method of making a crankshaft resistant to bending fatigue comprising the steps of:

• a) providing a microalloy steel having a composition consisting essentially of, in % by weight:
• 0.20 to 0.35 C,
• 1.00 to 1.50 Mn,
• 0.05 to 0.15 V,
• 0.001 to 0.06 S,
• balance essentially Fe;
• b) fabricating a crankshaft from said steel composition;
• c) induction hardening selected surfaces of the crankshaft;
• and
• d) tempering the crankshaft at a selected temperature on the order of 200.degree. C. (400.degree. F.) to 290.degree. C. (550.degree. F.) to achieve a desired surface hardness and residual compressive stress level.