Increase of fatigue strength and lifetime by deep rolling at elevated temperature of notched specimens made of steel SAE 4140

摘要

In comparison with traditional room temperature processes, deep rolling at elevated temperature leads to further increased fatigue strengths and lifetimes. This is demonstrated using notched bending fatigue samples made of quenched and tempered steel SAE 4140, which have been processed at room temperature and at 300 ℃ resp. near surface properties were analyzed before and after fatigue loading. It is shown that the positive effect of warm deep rolling is due to stabilized residual stress states which relax only slightly in the course of fatigue loading. The underlying microstructural processes are static as well as dynamic strain aging effects.