An Experiment on the Effect of Induction Hardening on Fatigue Strength

Abstract

The authors examined, from the standpoint of rapid heating, the influence of induction hardening on the fatigue limit of circular specimens of induction-hardened, plain carbon steel containing 0·41% C. The results were as follows : [table] From the above data it has been revealed that : 1) Adequate heating time gives maximum fatigue limit. The fatigue limit 80 kg/mm² is the highest value ever attained with the plain carbon steel containg 0·41% C. 2) The adequate heating time nearly coincide with the critical time deciding whether ferrite disappear or not. 3) There are proportional relations between fatigue limit and surface hardness. Such relations have been recognized at lower hardness, also when electric furnace quenched, but have not invariably been acknowledged in the case of ordinary quenching. 4) Some commercial criteria of optimum heating time were induced in connection with the diffusion of carbon in pearlite structure.