Augmentation of carburized mild steel weld properties to control chafing incidence

Abstract

Structural failures which occur in construction sites have been a major engineering concern worldwide. In Nigeria for instance, most failures which have been investigated, have been found to occur at welded joints. Therefore, this study is aimed at augmenting the wear and mechanical properties of weld metals to reduce the incidence of chafing, so that they can accommodate expected design loads and last through the expected service life. Deposited weld metals were carburized with a mixture of coal and calcium carbonate and the carburized weld metal were further tempered to reduce the brittleness and relieve the internal stresses built in of the carburized weld metal induced by the excessive absorption of carbon into the carburized weld metal. Wear analysis was conducted to determine the extent to which the carburized mild steel could resist wear or scratch (chafing) and the wear properties were compared with those of the uncarburized mild steel welds. It was found that wear rate of the carburized and uncarburized mild steel welds are 1.83 x 10-5 cm3/s and 5.94 x 10-5 cm3/s respectively. From the mechanical tests conducted the carburized mild steel welds are 1.79 times harder than the uncarburized ones. Also the carburized mild steel welds are 1.51 times higher in strength than the uncarburized mild steel welds. It is therefore, concluded that carburizing the mild steel welds has certainly improved their wear and mechanical properties and significantly reduced chafing. This study elucidates a step by step approach.