Effect of PVD residual stresses on the film mechanical properties, brittleness and adhesion

The effect of PVD coating’s residual stresses on their mechanical properties, brittleness and adhesion is presented. Coated cemented carbide inserts possessing diverse residual stress distributions in the film structure were manufactured applying different substrate bias voltages. As a consequence, compressive residual stresses are developed in the film structure. For detecting the influence of tensile residual stresses on the coating properties, a
portion of the coated cemented carbide inserts was annealed at 700oC in an inert gas atmosphere. The coating strength properties were determined via nanoindentations. The films’ brittleness was evaluated by nano-impact tests. Inclined impact tests were conducted for assessing the coating adhesion. The cutting performance of cutting inserts with various residual stresses was investigated in turning AISI 1045. According to the attained results, the residual stresses in the coating structure affect significantly their properties and wear behavior in cutting. Hereupon, a certain residual stress level can be considered as optimum.