Hardness distribution and impact toughness of carburized steel welded by SMAW

Joining carburized steel by welding process becomes promising technique to subtitute largely applied bolted connection on machine transmission elements which is often sustained from contact loading. The present study utilized microvickers and charpy impact tests to analyze the effects of welding current on hardness distribution and impact toughness of carburized steel joined by low-cost SMAW (shielded metal arc welding). The heat input played an important role to characterize the hardness distribution where the homogeneous distribution can be achieved by higher heat input controlled by higher welding current as a result of larger carbon-rich layer distribution within the fusion zone. The higher carbon enrichment at the center of fusion zone induced by higher welding current consequently reduced its ability to absorb impact energy after loading and thus degrade their impact toughness. (paper)