Corrosion, Wear and Mechanical Properties of Boron Added Cast 304 Stainless Steel

Abstract

The main objective of this research was to examine the effect adding B at 0, 100, 170 ppm had on the mechanical properties, wear and corrosion behaviour (in two different corrosive media) of cast 304 stainless steels. The microstructures, wear surface and corrosion morphologies were examined by optical microscopy, X-ray diffraction analyses and scanning electron microscopy (SEM). The cast 304 stainless steels with boron addition as 0, 100, 170 ppm, were used to investigate their corrosion behaviours by electrochemical potentiodynamic polarisation capacities in 5% HCl and 5% HNO3 solutions at laboratory environment. Wear tests were conducted in a pin-on-disc type wear tester. Optimum properties in relations of improved strength and wear resistance without loss in hardness were obtained when the cast 304 stainless steel contained 100 ppm B. At B contents higher than 100 ppm decrease of the hardness was accompanied an increase in strength and wear resistance. It was found that wear loss cast 304 stainless steel with B addition decreased with the increase of sliding distance, when compared with 0 ppm B addition cast 304 stainless steel. With regard to results of the corrosion experiment, Icor tended to decrease the addition 110 ppm B in 5% HCl solution, leading to a rise in the corrosion resistance. Adding B to the cast 304 stainless steels helped to enhance its corrosion resistance, except that its intergranular corrosion resistance reduced, which can be seen by examining the corrosion morphology. The improved wear behaviour and corrosion resistance of cast 304 stainless steel was attributed to the adding boron cast 304 stainless steel.