ABSTRACT

Economics dictates the selection of materials for corrosion applications. The most corrosion-resistant metal or alloy may not always be the choice because of its low abundance, high cost, fabrication difficulty, or unsuitability to meet the engineering requirements. Gold and platinum thus fail to be considered as viable engineering materials though they find exotic applications because of their excellent corrosion resistance. Cast irons and steels as plain carbon or alloyed varieties, on the other hand, still constitute the major bulk of engineering components and also find use in domestic applications. Iron or steel appliances may need elaborate corrosion prevention measures at times, but this will still be more economical in many cases than their replacement by costlier materials having higher corrosion resistance. Also, long-life equipment made with a higher corrosion resistance may not always be preferred by the industry as the process may become technically obsolete in a relatively short time. Conversely, a costlier metal may be the choice for a component to prevent its frequent replacement due to corrosion failures that hamper the production process and consequently the economics as a whole.