Influence of annealing treatment on the microstructure and mechanical performance of cold sprayed 304 stainless steel coating

► We studied influence of annealing treatment on microstructure and mechanical property of cold sprayed 304SS coatings. ► Annealing treatment changes the anisotropy microstructure of the as-sprayed coating to a uniform equiaxed grain microstructure. ► Annealing treatment changes the weakly mechanical bonded interfaces to metallurgical bonding. ► Annealing treatment significantly increased the tensile strength of the coatings from 67MPa to 357MPa. ► Annealing treatment changes the coatings mechanical performance from brittle type to plastic type. In this study, 304 stainless steel coatings were deposited on interstitial-free steel substrate by cold spraying method. The effect of annealing treatment on microstructure, microhardness, ultimate tensile strength and fracture performance of the coatings were studied. The results showed that annealing treatment had made a dominant contribution to heal up the incomplete interfaces between the deposited particles. Both of the microstructure and the mechanical properties have been obviously optimized by annealing treatment. In addition, the coating microhardness decreased from 345 HV0.2 for the as-sprayed coating to 201 HV0.2 for the annealed coating. The coating ultimate tensile strength increased from 65MPa for the as-sprayed coating to 357MPa for the annealed coating, which resulted from the increase of the metallurgically bonded areas in the coating induced by annealing treatment. Fracture morphology of the coatings also revealed that annealing treatment changed the fracture character of the cold sprayed 304 stainless steel coating from brittle type to plastic type.