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

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.

Research highlights
► 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