Influence of shot peening on corrosion behavior of low alloy steel

Abstract

Abstract Surface modification is an important technique for maintaining relatively favorable mechanical properties to surface properties and corrosion resistance. In this study, Surface shot peening technology is applied to low alloy steel production nanocrystallines. The microstructure near the surface layer was characterized by x-ray diffraction, transmission electron microscopy and electron backscatter diffraction. The corrosion behavior of the shot-treated surface layer was analyzed by polarization and pitting test, and the surface morphology of the corroded sample was observed by a scanning electron microscope. The results showed that the surface layer of the alloy after shot peening can be divided into three parts: equiaxed nanoparticle layer (NG), ultrafine grain layer (FG) and elongated fine grain layer (EG). Surface nanocrystallization improved the potential polarization behavior of low alloy steel in 3.5% NaCl solution. The microhardness of the near surface region showed a significant increase compared to the as-received steel sample, showing a more stable electrochemical performance. Shot peening also significantly reduced the pitting rate and maximum pitting depth in 10% FeCl3 solution. The surface nano-layer structure produced by the shot peening process could provide more nucleation sites, thereby improving the uniformity and compactness of the passivation film, resulting in better corrosion resistance. The above experimental results clearly showed that the overall and local corrosion resistance of the low alloy carbon steel in the chloride ion-containing solution can be improved by shot peening.