Observation for Transition Behavior of Oxide Inclusions on Gas Pressure Weld Interface

Gas pressure welding method does not need heavy equipments, and produces highly reliable joints. Therefore, it is often used for rails and reinforcing steel bars. However, if bonding work is poor, a large quantity of oxide inclusions remain at the weld interface, and those inclusions will cause the weld defect.So, in this study, oxide inclusions on weld interface were observed for clarifying existence state of oxide inclusions on each welding step by means of Scanning Electron Microscope and X-ray micro analyzer. As a result, it was clarified that Fe-O type oxide inclusions were formed on weld interface at early step, and then these oxide inclusions gradually changed to Si-Mn-O type oxide inclusions as welding process advanced. The transition behavior model of oxide inclusions on gas pressure weld interface was proposed. This result will contribute establishment of reduction of oxide inclusions.