Prediction of Hardness Profile of 4340 Steel Plate Heat Treated by Laser Using 3D Model and Experimental Validation

The paper presents a study of hardness profile of 4340 steel plate heat treated by scanning laser technique using 3D model. The proposed approach is carried out in three distinguished steps. First, a commercial software 3D model was developed using an adequate formulation and taking into account the nonlinear behaviour of the material. Second, the hardness curve is approximated from the temperature distribution using metallurgical assumptions related to the kinetic transformation and the temperature-time transformation diagram. Then, the case depth is analyzed quantitatively versus the beam power density and scanning speed. Finally, the developed approach is validated using experimental tests. The gap between simulation and experience results is determined. The obtained results allow predicting of the hardness profile with a fairly good precision.