Accelerated Determination of Fatigue Limit and S-N Curve by Means of Thermographic Method for X5CrNi18-10 Steel

A new thermographic method that enables simultaneous accelerated determination of the fatigue limit and the S-N curve was presented in this paper. The fatigue limit determination method was based on a constant rate of temperature rise occurring in second phase of the specimen fatigue life. The S-N curve determination method was based on energetic parameter with assumption of its dependency on the stress amplitude. The tests made on X5CrNi18-10 steel under reversed bending revealed that the fatigue limit value obtained from accelerated thermographic tests as compared to the value obtained from full test differs by 5.0 %. The S-N curve obtained by accelerated thermographic method fits inside 95 % confidence interval for the S-N curve obtained from full test.