Distortions and Residual Stresses of Gears Caused by Hardening : 1st Report, Through-Hardening of Solid Cylinder Made of S45C Carbon Steel

Abstract

Distortions of gear tooth caused by hardening decrease gear accuracies, and residual stresses due to hradening influence considerably the bending fatigue strength of gear tooth. But few papers are concerned with distortions and residual stresses of gears. In this report as the first step to studying the distortions and the residual stresses of gears caused by hardening, those of a cylinder caused by water quenching are studied theoretically and experimentally. Coefficient of thermal expansion during martensite transformation and heat transfer coefficient of water during cooling for the cylinders with various diameters, were obtained experimentally. The yield stresses of a cylinder during the martensite transformation were assumed from some of authors' measurements. The residual stresses were calculated applying these data by the elastic-plastic finite element method, and they were also measured experimentally by Sachs' method. Results of the numerical calculations and experiments showed good coincidence qualitatively and quantitatively. Consequently, availability of calculation was confirmed.