Abstract
'All weld' deposited rectangular blocks of C-Mn steel were prepared by the multipass submerged arc process, using different welding currents (500-750 A) and speeds (40-60 cm/min). A filler wire of 4 mm diameter and a basic agglomerated flux were employed. Varying the welding parameters influenced the macrostructure comprising coaxial dendrites and reheat refined regions whose amounts were determined by quantitative metallography. The influence of dendrite content, on the toughness as influenced by temperature and orientation of the specimens (LT, TS and SL) was assesed both in the as welded and in the heat treated (873 K) conditions.
An increase in the area fraction of dendrites beyond about 37% adversely affected the toughness which was found to be lowest in the LT direction. A post weld heat treatment carried out at 873 K improved the overall toughness due to spheroidization of cementite, especially within the refined equiaxed regions, resulting from 'reheating' during multipass deposition.
