The evaluation of corrosion rate on welded specimen of low carbon steel

Abstract

The aim of this work is to study the effect of welding on corrosion rate of low carbon steel in Sabha water. Some of the specimens welded by V joint and the other left without welding. The tests carried out on all the specimens are corrosion test. The corrosion media used in this study was Sabha water.  The anti-corrosion paint that was used is undiluted AL- WAHA paint (from local market), according to the paint results, it was found that the drying time for AL- WAHA paint should be more than 24 hours when used without dilution.  According to the visual observations, it was seen that the color of the all-exposed areas to the environment was changed to the dark red orange color.  Also from the obtained results, it was found that the average corrosion rates for the unpainted heat affected zone areas (HAZ) are less than that for unpainted welded metal areas (fusion region) and higher than unpainted base metal areas for welded specimens, this is because the structure of the HAZ is changed to the carbide (cementite) which is hard and tend to be has more corrosion resistance than welded metal area (fusion region).  Moreover, the average corrosion rate for non-welded specimen is less than that for unpainted base metal for welded specimens.  Pitting corrosion and Galvanic corrosion were seen on the painted specimens, while, the type of corrosion of the non-welded specimens was uniform corrosion.