Effect of surface nanocrystallization on the corrosion behaviour of AISI 409 stainless steel

► SMAT enables graded layer structure with nano-sized grains at surface ► SMAT increase surface roughness, crystalline imperfections and microstrain ► Surface nanocrystallization promotes passivity and increases corrosion resistance ► Increase in microstrain and defect density decreases the corrosion resistance The influence of surface mechanical attrition treatment (SMAT) on the corrosion behaviour of AISI 409 grade stainless steel in 0.6 M NaCl was studied. SMAT using 2 mm ∅ 316L stainless steel (SS) balls for 15, 30 and 45 min and 5 mm ∅ balls for 15 min offers a better corrosion protective ability. In contrast, treatment using 5 mm ∅ balls for 30 and 45 min and by using 8 mm ∅ balls for 15, 30 and 45 min, induces microstrain and defect density that results in a decrease in corrosion resistance.