ENHANCEMENT OF MECHANICAL PROPERTIES AND CORROSION RESISTANCE OF LOW-CARBON STEEL WITH GRADIENT MICROSTRUCTURE BY IMPACT PEENING AND RECOVERY TREATMENT

Abstract

A gradient microstructure was generated on a low-carbon steel/Cr alloy through severe deformation by an impact peening and a recovery treatment. The microstructure was probed by scanning electron microscopy, energy disperse spectroscopy and x-ray diffraction. The microhardness, tensile strength and electrochemical corrosion resistance of the gradient microstructure surface were studied. The material with a fine grain gradient microstructure on the surface had increased microhardness, strength, ductility and corrosion resistance compared to a low-carbon steel standard. When a Cr solution was added, a hard (Fe,Cr)7C3 phase was generated, suggesting that Cr alloying plays important roles in these enhanced properties.