TWI Industrial Member Report Summary 155/1981
By J Honeycombe, J A Barlow and T G Gooch
A study has been made of submerged-arc welds produced in Types 316 (plate thickness 25mm) and 347 (plate thickness 13.5mm) using currents of up to 1350A and arc energies of up to 6kJ/mm. These levels are considerably greater than those in current industrial practice, and the objective of the programme was to determine whether the use of higher arc energies is feasible, with the potential economic advantages this would imply.
Welding was performed successfully with a commercial flux and Type 316L wire, and no evidence of macroscopic weld metal solidification or HAZ cracking was found. The tensile and Charpy impact properties of the welds were examined, and found generally satisfactory. As assessed by the Strauss test, no increase in susceptibility to intergranular corrosion with increasing welding current and arc energy was observed in the HAZ or weld deposit, at least within the parameters employed. In some of the welds made at higher currents, small shrinkage voids were found in reinforcement regions, in association with a particular type of solidification structure. It is considered that the propensity to form these defects may be reduced or eliminated by modifications to the submerged-arc flux employed.
The overall conclusion reached is that scope exists for using arc energies higher than those now commonly employed for the submerged-arc welding of austenitic stainless steels with commensurate increase in productivity.