Fatigue limit evaluation via infrared thermography for a high strength steel with two strength levels

The fatigue limit of a high strength steel (GCr15) with two strength levels (2372 MPa and 1044 MPa) was evaluated in terms of energy dissipation during high-cycle fatigue (HCF) and very-high-cycle fatigue (VHCF) process. Two methods based on the maximum temperature variation and intrinsic energy dissipation were used to assess the fatigue limit and the predicted results were in agreement with those of conventional fatigue tests. The grain boundary of tempered martensite for the specimen group with higher strength acts as barriers to resist dislocation gliding and multiplication, and thus it behaves lower heat dissipation and higher fatigue strength than the specimen group with lower strength.