Abstract
In order to clarify the relationship between fatigue strength and hardness of precipitation strengthening type stainless steel: A286, tensile tests, fatigue tests and Vickers hardness tests were performed. As a result of the tests, A286 steel have high tensile strength as well as low fatigue strength. Then, from the result of hardness test, there is large variability in hardness distribution of A286 steel. High hard zone and low hard zone were found in a specimen of A286 steel. The hardness of the zone in which many cracks initiated, is lower than the zone in which few cracks initiated. It is considered that high tensile strength is based on average both high hardness zone and low hardness zone when tensile test, and low fatigue strength was caused by the fatigue cracks which are easy to initiate and propagate in low hardness zone. Therefore, this is the reason why the fatigue strength ratio of A286 steel is lower than most steel.
