Effect of heat input on weld bead geometry of submerged arc welded ASTM A709 Grade 50 steel joints

► Increasing heat input increases reinforcement, bead width, penetration, penetration and deposition areas, and HAZ size, but decreases contact angle. ► A linear correlation is found between cooling time and total nugget area, cooling interface length, as well as nugget parameter. ► The bead width-to-depth ratio and percent dilution do not vary appreciably with heat input. ► Electrode melting efficiency increases with increasing heat input for single wire welding, but plate melting efficiency does not change. A series of measurements was carried out on specimens of submerged arc welded plates of ASTM A709 Grade 50 steel to determine how variation in heat input achieved using single and double wires affected bead reinforcement, bead width, penetration depth, contact angle, heat affected zone (HAZ) size, deposition area, penetration area and total molten area. The level of dilution and different melting efficiencies were calculated and their variation with heat input was analyzed based on the acquired measurements. The cooling time from 800 to 500°C was also related to various weld bead characteristics (e.g., total nugget area, heat transfer boundary lengths, bead width-to-depth ratio, and nugget parameter). The bead reinforcement, bead width, penetration depth, HAZ size, deposition area and penetration area increased with increasing heat input, but the bead contact angle decreased with it. The electrode melting efficiency increased initially and then decreased with increasing heat input, but the plate melting efficiency and percentage dilution changed only slightly with it. Cooling time exhibited a very good linear relationship with the total nugget area, heat transfer boundary length, and nugget parameter.