Abstract

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COMPARATIVE STUDY OF THE RESPONSE OF COMMERCIALLY AVAILABLE ELECTRODES TO UNDERWATER-WELDING AND AIR-WELDING

Dr.M.I Khan,Yaqoob Ali Ansari , Dr. Shahnwaz Alam


The first ever underwater welding was carried out by British Admiralty- Dockyard for sealing leaking ship rivets below the water line. Underwater welding is an important tool for underwater fabrication work. In 1946, special waterproof electrodes were developed in Holland by ‘Vander Willingen’In the past half century a great deal of research effort has been directed towards the development of underwater shielded metal arc wet welding process. Different investigators have reported results of their findings using different types of coated electrodes. The present work reports a systematic study of ten different varieties of commercially available electrodes regarding their response to underwater welding. These electrodes have been evaluated in stages on the basis of (1) arc stability (2) electrodes running characteristics through bead- on- plate and bead-in-groove trials and (3) controlled thermal severity tests. The electrodes successful in the final screening have been further tested for the mechanical properties of the joints they produced. Among the electrodes tested oxidizing iron-oxide electrodes showed better arc stability, produced smooth and regular beads, free from undercuts , no cracks in weld metal and heat affected zone (HAZ) were observed even in CTS tests, metal transfer was free from short circuits and mechanical properties were superior to the commonly used rutile iron-powder electrodes.