Influence of Fe content on the heat treatment response of mixed Fe-316L stainless steel cold sprayed coupons

One of the advantages of cold spraying is the ability to spray mixed feedstock powder batches to fabricate coupons with the desired chemical composition. One such application is the fabrication of biodegradable stents for coronary artery disease, made by mixing iron and 316L stainless steel powders. Upon spraying, the coupons are heat treated into an alloy to homogenize the microstructure and increase their ductility. However, preliminary work showed that increasing the iron content can have a negative impact on ductility. In this work, the goal is to investigate the effect of iron content on the heat treatment response of the coupons, and to optimize the process so that the coupons attain the desired ductility for the application. For that purpose, a pure 316L stainless steel coupon and a 65 wt% 316L stainless steel – 35 wt% iron coupons are cold sprayed at similar spray parameters and heat treated at a series of different conditions afterwards. The fabricated samples (as sprayed and heat-treated) are microstructurally characterized, and their mechanical properties are evaluated by tensile testing and shear punch testing.