The Study on the Corrosion Behaviour of Welded and Unwelded Medium Carbon Steel in Sodium Chloride (Nacl) Solutions

Abstract

The research work was based on the study of the corrosion behaviour of the welded and un-welded medium carbon steel in sodium chloride solutions. The Sodium chloride solutions used are 1ml, 2ml, 3ml and 4ml for both welded and un-welded medium carbon steel in NaCl. The experiments were conducted in two ways, the weight loss analyses of measurements and using the electrochemical analyzer workstation to determine the potential dynamic of the samples. The samples for the weight loss measurements were prepared from rolled products obtained at the foundry shop. Two medium carbon steel materials were sourced with different chemical compositions as sample A and B. The materials were prepared to accommodate the experiments for the determination of welded and un-welded medium carbon steel. A total of sixty-eight (68) samples were produced, prepared and used for the weight loss measurements /analyses the experiments. Thirty-four of the samples each were prepared for both the welded and un-welded experiments. All the samples were produced and prepared through the use of various machining processes with the use of a lathe machine for planning, milling. Thirty-four (34) of the sample preparation were further welded in readiness of the experiments. Sixty –eight breakers were sourced for and used. Ten (10) other samples were used for the determination with the use of the electrochemical analyzer. The chemical compositions of the medium carbon steel were determined with the use of SPECTRO Analytical Instruments. A metallurgical inverted optical microscope was used to determine the microstructures of the materials. The Scanning Electron Microscopy with EDS was used to determine the morphologies of the materials. The thirty-four of the samples were welded this process was performed to determine the effects of welding on the material surrounding the weldments. These materials were made into sizes with the use of power hacksaw (i.e. 2cm by 2cm). Other materials were prepared to 1cm x 1cm thickness from the same materials. The Tafel plot experiments and that of the open Circuit Potential Time (OCPT) were carried out with the use of Electrochemical Analyzer/ Workstation. The Medium carbon steel materials were exposed for fifty – four (54) days, with an interval of 3days. The corrosion rates analyses were determined and the graphs of the corrosion rates (mm/yr.) and other parameters were used plotted against No of days exposed.