Abstract
The fatigue crack growth behavior of SUS 304 stainless steel when one slow-fast strain cycle was introduced to the fast-fast strain cycles was investigated at the temperature of 873K. It was found that the fatigue crack growth rate in the fast-fast strain cycles was accelerated by the introduction of one slow-fast strain cycle. It was also found that there was a linear relationship between the size of the region where the above acceleration occurred and the value of creep J-integral range which was produced just when one slow-fast strain cycle was introduced. The distribution of hardness just below the fracture surface, where the above acceleration occurred, was similar to the one in the pure slow-fast strain cycle fatigue. From the results thus obtained, it was thought that the one slow-fast strain cycle affected the stress-strain field at the crack tip and contributed to the acceleration of crack growth rate.
