ISSN(Online) : 2319-8753 ISSN (Print) : 2347-6710 International Journal of Innovative Research in Science, Engineering and Technology (An ISO 3297: 2007 Certified Organization) Website: www.ijirset.com Vol. 6, Issue 2, February 2017 Copyright to IJIRSET DOI:10.15680/IJIRSET.2017.0602077 1840 Corrosion Behaviour of Mild Steel in Atmospheric Exposure and Immersion tests Leckraj Chamane 1 , Dr. B.Y.R Surnam 2 Graduate Student, School of Mechanical Engineering, Beijing Institute of Technology, China 1 Senior Lecturer, Mechanical and Production Engineering Dept., University of Mauritius, Mauritius 2 ABSTRACT: Corrosion testing is an essential tool in the development of corrosion protection strategies. Its prominence cannot be overlooked in this world of limited resources. Accelerated tests including the alternate immersion test and the simple immersion test, were performed according to ISO 11130 and ASTM G31 to study the corrosion behaviour of mild steel. A time correlation has been established between these tests and the corrosion categories of ISO 9223 to get an idea about the testing period for a particular amount of expected corrosion loss in a specific atmosphere. They were also compared with atmospheric exposures at a marine site in Mauritius. Test specimens were visually inspected to understand the corrosion behaviour in these accelerated tests. The study concluded that a concentration other than 3.5% NaCl should be envisaged for the alternate immersion test to at least follow a trend similar to that of atmospheric corrosion. KEYWORDS: corrosion, immersion tests, atmospheric, mild steel, NaCl I. INTRODUCTION Corrosion tests can be used to monitor the corrosion behaviour of materials in specific environments. They are classified into three main groups; exposure tests, pilot tests and laboratory tests. An exposure test involves the exposure of the material to the service environment. Exposure tests provide accurate results but they usually require a few years to provide results. Pilot tests are conducted to compare the corrosion performance of materials in service. They require the substitution of existing components in a system by components made of the material to be assessed. In laboratory tests, the metal is exposed to a more aggressive environment than the actual service environment [1]. In the lifetime prediction of the corrosion performance of materials in specific atmospheres, atmospheric exposures have been very reliable and have been performed worldwide [2]. However, in many circumstances rapid and reliable prediction of the materials’ performance in corrosive environments is required and, in these situations accelerated corrosion tests are preferred [3]. The salt spray test is a commonly used accelerated corrosion test [2]. Atmospheric corrosion is highly dependent on pollutants and humidity cycles. The salt spray test, however, involves neither humidity cycling nor SO2 and thus does not provide the conditions of a general atmosphere. It has been highlighted that the salt fog test induces consistent conditions throughout the test cycle and consequently forces a consistent corrosion rate which does not occur in a real- time atmosphere. Consequently, the results obtained do not correlate satisfactorily with those from outdoor exposures for a general use [2]. II. RELATED WORK Immersion tests can be used as an inexpensive alternative to salt spray tests. They involve the immersion of the specimens in a corrosive liquid and measurement of mass loss for a period of time. Two common types of immersion tests are:  The Simple Immersion test It involves the complete immersion of the specimens in a corrosive liquid and measurement of mass loss for a period of time. It is the most economical method for assessment of materials and eliminating those materials that must not be