THE EFFECT OF DIFFERENT LEVEL SEAWATER EXPOSURE ON WELDED AND UNWELDED CARBON STEEL

Abstract

Carbon steel, the most widely used engineering material, accounts for approximately 85%, of the annual steel production worldwide. Despite its relatively limited corrosion resistance, carbon steel is used in large tonnages in marine applications, nuclear power and fossil fuel power plants, transportation, chemical processing, petroleum production and refining, pipelines, mining, construction and metal-processing equipment. The aim of this study is to determine the effect of exposure level and duration of exposure on corrosion rate of carbon steel. Two types of specimen which is welded specimen and unwelded specimen were used for immersion testing in natural seawater. Four different level which is atmospheric zone, tidal zone, fully submerged zone and subsoil zone were used throughout the immersion test. The immersion test result show that the welded specimen that conducted at tidal zone for duration of 1008 hours (42 days) have the highest corrosion rate which is 1.797 mm/year. Meanwhile, the tensile test result show that the unwelded specimen at atmospheric zone have the highest tensile strength which is 280.36 N/mm 2 after exposure in seawater for duration of 1008 hours (42 days). The others factors that affecting and influence the corrosion rate of welded and unwelded carbon steel were also discussed.