Influence of the Step Martempering and Anisotropy on the Distortion Value a Cold Rolled Hot Work Tool Steel

In this investigation, the role of the structural anisotropy due to cold rolling on the distortion value of hot work tool steel employing in moulding before and after the hardening heat treatment was studied. For the hardening treatment, was used a step martempering process. Distortion amount was calculated by flatness factor in 3 states; after machining, after stress relief treatment and after martempering. For purpose of the consideration of the anisotropy effect on the steel distortion, were prepared samples dependent on the rolling direction in 3 geometrical states. Before martempering, the distortion value of the samples is very low and negligible. It is also independent on the sampling direction. Thus it is an isotropic characteristic. Results revealed that distortion is induced in the martempered steel. It is also significantly different in various directions of sampling. It is implied that in the hardened steel, distortion is an anisotropic property. The lowest distortion is belonging to sample which is perpendicular to the rolling direction. Hardeness measurement showed that this specification is an isotropic property in both before and after hardening and is not affected by the geometrical direction of sampling.