EFFECT OF WARM MULTI-AXIAL FORGING ON THE MECHANICAL AND CORROSION BEHAVIOR 305 GRADE STAINLESS STEEL

Abstract

The basic purpose of using stainless steels is the high corrosion resistance. Among stainless steels, austenitic stainless steels are most commonly used which are nonmagnetic. Using various severe plastic deformation techniques the mechanical strength of these steels can be improved which results in weight saving. By severe plastic deformation refinement of grains is done, sometimes even to ultrafine scale. But with improved strength, the corrosion resistance should also be better or at least comparable to the received steel. Otherwise, the applications of such steel will find a very limited area. The aim of this work is to study the mechanical and corrosion behavior of such severely deformed 305 stainless steel, a grade which is very ductile. For mechanical behavior, tensile and hardness test were carried out whereas for corrosion behavior various corrosion tests such as potentiodynamic tafel test, cyclic polarization and electrochemical impedance spectroscopy were carried out in 3.5 wt% NaCl solution. An increase in uniform corrosion rate and a decrease in susceptibility to pitting corrosion is observed, which can be attributed to the increased grain boundary volume and the uniform distribution of pit forming impurities due to severe plastic deformation. The corrosion behavior is highly influenced by the passive layer properties formed on the surface of steel before and after severe plastic deformation.