TWI Industrial Member Report Summary 472/1993
By D J Abson
High toughness of C-Mn steel weld metal is generally associated with the development of a fine-grained acicular ferrite microstructure. It is known that oxide inclusions can assist the nucleation of acicular ferrite in weld metal produced by the submerged arc, MHA and MAC processes, and that acicular ferrite formation is hindered by an excess of Al over oxygen. Much less is known about the role of Al/O balance with low oxygen welding processes, such as TIG, electron beam or laser. In the present work, hot wire TIG welds have been studied to investigate the influence of varying Al on low oxygen weld metal. Parent plates with differing Al contents and selected commercial solid and cored wires, some of which contained substantial additions of Ti, were employed for this study, in which weld metal composition, hardness and microstructure have been investigated.