Residual Stress Caused in the Disc by Induction Hardening from Its Periphery

Abstract

Effects of induction hardening conditions on the residual thermal and quenching stresses were examined with the circular discs hardened from their periphery. Principal results are as follows :
A. Residual thermal stress
(1) When the gradient of the heating temperature distribution is steep, the tangential stress σ_t is compressive in the inside region of the disc and tensile in the outside region. The radial stress σ_r is compressive in all regions. (2) As the gradient of the heating temperature distribution is gradual, the region where the tensile stress σ_t is brought about moves to the inner side of the disc. (3) In the outside part of the disc, the curve of σ_t assumes an upward form. (4) Regarding to the stress in the inside only, as the steepness of the heating temperature gradient becomes gradual, the value of the compressive stress σ_t once increases and then decreases, and with very gradual gradient it turns to the tensile.
B. Residual quenching stress
(1) σ_t is compressive in the outside part of the disc. (2) When the gradient of the heating temperature distribution is steep, large tensile σ_t exhibits in the part neighbouring to the hardened layer.