Predictive modeling and experimental results for laser hardening of AISI 1536 steel with complex geometric features by a high power diode laser

This paper presents predictive modeling and experimental results on laser hardening of AISI 1536 steel shafts with a complex geometric feature. A three-dimensional thermal model is used to predict the workpiece temperature distribution, which is coupled to a two-dimensional kinetic model to predict the resultant hardness and phase distribution. Surface temperature measurements are performed to validate the thermal model, while the kinetic model is validated through furnace hardening and laser hardening experiments. A 2.5-mm case depth is achieved on simple geometry parts, while a 1.5-mm case depth is obtained on parts with a groove of 2.0-mm radius. The case hardness values and distributions show good agreement with predicted results and are found to be uniform throughout, with the values between 55 and 57 in Rockwell C.