The Development of Heat Treat Stresses and Their Effect on Fatigue Strength of Hardened Steels

A theory is proposed to explain how high compressive surface stresses can be introduced into steels by severe quenching. Experimental data are presented which show the effect of quench severity, hardenability, section size, tempering, and decarburization on the surface residual stresses in quenched steel cylinders. Fatigue tests on small and large specimens of seven selected steels confirm the significant effect of residual stress on fatigue strength.