Residual stress optimization of technological processes with the aim of ensuring adhesion of nickel or chromium coatings on parts made of titanium alloys

Abstract

Work on ensuring adhesion of chromium coating on parts piston with a rod made of ВТ3-1, ВТ22 titanium alloys was carried out based on the examination of residual stresses. Ensuring the adhesion of coats was conducted in two stages: at the first stage strengthening treatment was used, and at the second stage optimization of grinding conditions by residual stresses was carried out. A method of predicting process-induced residual deformation by equivalent initial stresses is presented. Residual stresses in a surface layer of specimens cut out of the strengthened parts were studied. It was established that compressive residual stresses in the surface layer ensure the coating adhesion in chromium plating of parts made of titanium alloys. It was shown that ensuring adhesion of coatings on parts made of titanium alloys can be obtained both by strengthening treatment and without it, due to the optimization of grinding conditions. The results obtained made it possible to eliminate surface tempering in the process of grinding parts made of titanium alloys, to ensure favorable technological heredity not only for the parts under examination, but for other parts such as pistons, hydraulic cylinders and rods.