高周波焼入れした機械部品の残留応力について

抄録

It is known that induction hardening is the most effective method for increasing mechanical strength, especially fatigue strength. On its application, we think that residual stress produced by heat-treatment comes into question and becomes an important element. Therefore, we now measured the residual stress of actual machine parts ; such as an electric engine's axle, a crankshaft for fatigue test, an electric car's pinion, and a vibration conveyor's laminated spring by using resistance wire strain gauge. The following information are derived from these experiments. 1. On symmetric induction hardened machine parts, residual stress in hardening surface layers is compression stress. 2. On both stationary and progressive hardening method, residual stress in surface layers is compression stress. 3. On boundary surface layers of an electric engine's axle, the residual stress is also compression stress, smaller than in hardening surface layers.