Evaluation of Corrosion Rate and Scratch Resistance in Chromium Alloyed Irons Influenced by Manganese Addition and Process Parameters

To protect metal surfaces from corrosion due to chemical attacks thin layers of chromium, nickel and zinc are deposited. In bulk materials such as carbon steel, alloying elements like chromium, manganese, and copper are added to control the rate of corrosion yielding finer grains and increase the formation of a non-adherent layer in seawater and acidic media. Further, improvement in the wear resistance in terms of scratch parameters is envisaged through the adoption of chromium as a hardening agent and manganese as the gamma stabilizer. The corrosion behavior together with scratch resistance in high chromium manganese iron alloys has not yet been reported. Keeping the above facts in mind, in the current work chromium manganese iron was produced by induction melting process and the corrosion rate and scratch resistance were evaluated. Manganese at two levels 5 and 10% by weight with varied section sizes of 12, 24, and 40 mm were assessed for their composition, hardness, density, carbide volume and retained austenite in the chromium iron alloy. The results reveal that both the scratch width and depth increases with the increase in manganese content as well as section thickness irrespective of whether it is as-cast or heat-treated, whereas corrosion rate decreases. The correlations have been evolved among the corrosion rate, scratch parameters, and morphological topography obtained through light and scanning electron microscopy. The investigation reveals that the section thickness of 24 mm may be the best choice for achieving higher scratch resistance and lower corrosion loss in components such as liners, impellers, etc.