STRESS IN ARC SPRAY COATINGS AND THEIR INFLUENCE ON ABRASIVE WEAR RESISTANCE

Abstract

The effect of type I residual macro-stresses (σ_res) on the abrasive wear resistance of arc spray coatings (ASCs) was studied. Based on studies of the phase compositions of ASCs and its influence on the level of residual stresses σ_res, an empirical formula for determining these stresses is proposed. The workability of ASС depends not only on the level of σ_res in the coating, but also on its cohesive strength σ_c. Therefore, their ratio σ_res/σ_c is proposed as an indicator characterizing the susceptibility of ASC to cracking. It was empirically established that when σ_res/σ_c > 0.75, the coatings are prone to microcracking, and when σ_res/σ_c > 0.85, a network of microcracks is formed in them. Heating the samples before applying ASC with cored wires, as well as tempering after their spraying, reduces the tensile residual stresses in the coatings, promotes the precipitation of dispersed carbides and borides into their structure and, as a result, significantly increases their abrasive wear resistance.