Influência dos parâmetros de roleteamento sobre a integridade superficial, resistência à corrosão e vida em fadiga do aço ABNT 1045 recozido

Abstract

The performance of metallic components can be severely impaired by exposure to aggressive environments, such as corrosive media, due to natural oxidation processes that progressively degrade the material’s microstructure. This study aimed to investigate the influence of deep rolling — a mechanical surface treatment — on the fatigue strength of annealed AISI 1045 steel after exposure to a 3.5 wt.% NaCl saline solution for 72 hours. The effects of deep rolling pressure and tool feed rate on the subsurface microstructure, surface roughness, electrochemical behavior, fatigue strength, corrosion mode, and fractured surface characteristics were evaluated. Microstructural analyses revealed increased plastic deformation, higher hardness, and grain refinement in the subsurface region with increasing deep rolling pressure. Roughness parameters were significantly reduced after deep rolling compared to the turned condition, with a decrease of up to 80% in Ra value. However, no significant changes were observed in the electrochemical corrosion resistance. Conversely, fatigue tests indicated that deep rolling substantially increased the number of cycles to failure for the material exposed to the electrolyte, especially under higher pressure and lower feed rate conditions. The condition deep rolled at 140 bar and 0.04 mm/rev and subsequently exposed to the saline solution exhibited superior performance compared to the turned and unexposed material. Additionally, deep rolling proved effective in modifying the surface corrosion mode, with lower deep rolling feed rates contributing to a reduction in pit density on the component surface. Fractographic analysis indicated fewer crack nucleation sites for the deep-rolled material, owing to the improved surface finish promoted by the deep rolling process.