Surface integrity of machined AISI D2 steel and its effect on the adhesion of a PVD-AlCrN coating

The permanent importance of molds and dies in the industry motivates new studies to obtain optimized parameters and processes, which contribute to the reduction of their wear and increase of their life cycle. Regarding this, coated forming tools are often applied and this paper aims to investigate the influence of the surface preparation of hardened AISI D2 steel substrate on the adhesion characteristics of an AlCrN coating deposited by physical vapor deposition (PVD). For this, an end milling process with different cutting conditions was applied and the coating was tested by indentation and scratch tests. From the obtained results, it could be observed that cermet cutting inserts used in milling process led to higher compressive residual stresses and lower roughness values in the substrate in comparison to cemented tungsten carbide inserts, increasing the critical load required for coating failure. Although scratch tests demonstrated enough sensitivity to differentiate substrate surface properties, indentation tests had no success.