Microscopic fatigue crack behavior in precipitation strengthening stainless steel A286

Abstract

In order to clarify the fundamental fatigue strength characteristic of precipitation strengthening type stainless steel:A286, fatigue tests were performed. In the fatigue test, the authors paid attention to the behavior of microscopic fatigue cracks in order to make clear fatigue strength properties more than those with usual fatigue tests. As a result of the fatigue test, the fatigue strength characteristic of A286 became clear as shown below. The crack of a size according to a crystal grain diameter is easy to initiate and propagate by Mode II. Many cracks initiate and propagate even if the stress is around the fatigue limit and the fatigue crack cannot stop, then the cracks coalesce and it becomes longer, and finally results in a failure. This is the reason why the fatigue failures occur even after 107 cycles.