PRODUCTION AND WELD JOINT PERFORMANCE EVALUATION OF ARC WELDING ELECTRODES FROM DANA ROLLING MILL SCALES

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Author

Presented To

Department of Engineering

ABSTRACT
This study explored the possibility of producing Iron Oxide based arc welding electrodes using mill scales from Dana rolling mill. The performance of the weld joints using the produced electrodes and a foreign electrode was also examined. It is estimated that 4000-5000 tons of mill scales are produced annually without any immediate industrial application. The mill scales were collected prepared and analyzed using the Oxford 800 X Supreme XRF machine. The report of the analysis shows the presence of predominantly Iron Oxide, which is an important constituent in electrode coating. The flux compositions were generated using the Hadamard multivariate chemical model. Using this model, twelve different flux compositions emerged within given ranges of the constituent flux elements. Four of the flux compositions were used to produce electrodes using sodium silicate as binder. The electrodes were produced manually by means of a wooden mould. The produced electrodes (E6020, E6027, E6024 and E6030) and a foreign electrode were used to carry out weld on some prepared samples. The welded joints were tested for tensile, hardness, and impact tests. The results of the tests conducted on all the welded joints using the produced electrodes and the foreign electrode shows that all the produced electrodes with the exception of electrode type E6030 compete well with the foreign electrode (Oerlikon). Electrode type E6020 gave the highest tensile and hardness test results of 453N/mm2 and 457.1N respectively. The maximum impact energy was found to be 94.9 joules on the sample welded with the electrode type E6030. The micrographs of the weld joint using electrode type E6027 revealed a coarse pearlite (black matrix) and an elongated ferrite (white matrix). To this end, this study established the need to maximize the use of mill scales (an industrial waste) for the production of arc welding electrodes and by so doing conversion of waste to worth would have been achieved.