CORROSION STUDIES ON SHAPE WELDED STEELS

Abstract

The present study has been done to analyze the aqueous corrosion behaviours of low carbon steel (C - 0.097%, Mn - 1.59%, Si - 0.24%, S - 0.024%, Cu - 0.3%, P - 0.04%) processed by the new method of shape welding and rolled steel (C - 0.12%, Mn - 0.4%, S - 0.01%) in the 92% and 96% concentrated sulphuric acid solutions. This shape welding technique is being developed to manufacture the components like rotor of shafts, reactor pressure vessels and valves etc. by welding method alone. Shape welding method has specific advantages for the manufacturing of thick walled components of any dimensions and to a wide range of high strength, creep and corrosion resistant properties. The corrosive behaviour was studied under total immersion test (92% and 96% H2SO4 solution). The exposure time was around 250 hours. The corrosion rate was calculated by weight loss method and was calculated in terms of mdd. The shape welded steel was found to have better corrosion resistance than the rolled steel of similar composition under similar conditions of temperature and concentration of H2SO4 solutions. Increase in temperature from 150C to 500C led to substantial increase in corrosion resistance for both the steels. While the concentration of H2SO4 from 92% to 96% led to a marginal increase in corrosion. The corrosion rates decreased with increase in time of exposure.