Corrosion characteristics of newly developed structural DMR-1700 steel and comparison with different steels for industri
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ON and steels are the most versatile, least expensive, and most widely used materials for construction of many engineering systems. They are unequaled in the range of mechanical and physical properties with which they can be endowed by alloying and heat treatment. Their main disadvantage is that they have poor corrosion resistance in even relatively mild service environments. Corrosion can reduce the load carrying capacity of a component either by generally reducing its size or by pitting. Pitting not only reduces the effective cross section in the pitted region but also introduces stress raisers that initiate cracks. Any technique that reduces or eliminates corrosion will extend the life of a component and increase its reliability. In addition to the corrosion prevention methods, design and material selection are important to improve overall corrosion performance of a component. The three inter-related factors that drive materials selection for corrosion control are the corrosivity of the environment, the corrosion resistance of the material, and the acceptable rate of attack. Premature failures occur during service due to the presence of corrosive compounds if suitable materials in association with appropriate coatings are not selected for fabrication of components of the critical systems.[1–6] Corrosion affects the efficiency of the systems significantly.[2–5] The most prevalent mode of corrosion is pitting and crevice corrosion.[6] In order to achieve maximum efficiency of the system, it is highly essential to eliminate failures by selecting appropriate and cost-effective materials, which is possible by using advanced materials and coatings with enhanced properties. The possible ways of controlling corrosion are application of coatings, linings, metal cladding, corrosion inhibitors, and higher alloying.[7–10] Among these, application of suitable coatings appears to be a promising method of corrosion I. GURRAPPA and G. MALAKONDAIAH, Scientists, are with the Defence Metallurgical Research Laboratory, Kanchanbagh PO, Hyderabad500 058, India. Contact e-mail: [email protected] Manuscript submitted December 14, 2005. METALLURGICAL AND MATERIALS TRANSACTIONS A
control in terms of cost effectiveness and service life. This aspect is proved in various applications.[11–22] DMR-1700 is a recently developed ultrahigh strength low alloy steel with improved mechanical properties as compared to other low alloy steels.[23] However, detailed corrosion characteristics are not yet investigated, though some stress corrosion cracking studies have been carried out in 3.5 pct NaCl solution.[24,25] The present investigation is aimed at studying the corrosion characteristics of a newly developed DMR-1700 structural steel in detail, comparing the properties with both stainless steels such as 316L, 304SS, and SDSS and widely used low alloy steel EN-24 and then recommending a suitable protective coating to fabricate the components for different industrial applications. The surface morphologies of different corroded steels have been observed
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