Effect of path-plans of automatic arc spraying on coating residual stresses

Path-plan is one of the important aspects affecting the residual stresses of arc sprayed coatings.Four types of spraying paths were designed based on an automatic arc spraying system.The 82B high carbon steel coatings were prepared by using the designed paths,and the residual stresses on the as-sprayed coating surfaces were measured with an X-ray residual stress tester.The structure and phase composition of the steel coating were also investigated with a metallographic microscope and an X-ray diffraction instrument,respectively.The experimental results show that the distribution of the residual stresses for the coating prepared by the "ring inward" type spraying path is the most uniform,and the stress peak value is the lowest in other coatings;but the distribution of "parallel and symmetric" type path is the worst.The coating microstructure is mainly featured by block-like martensite and oxide.Based on these investigations,the formation mechanism of the quench stress,thermal stress and the stress induced from phase transformation of the high carbon steel coating material was discussed.