TWI Industrial Member Report Summary 271/1985
By M N Watson
Five 12.5mm thick C-Mn-Si-Al-Nb structural steel batches to BS 4360 Grades 43E and 50D have been laser welded. Carbon contents ranged from 0.11% to 0.15% and sulphur from 0.005% to 0.019%. Laser powers in the range 5.2kW to 9.1kW were used. Weld metal hardnesses, microstructures and Charpy impact properties were evaluated and were compared to results obtained on other steel compositions (previously reported in Welding Institute Research Report 243/1984). Charpy impact test 27J transition temperatures of -40°C or below were found in welds with a fully martensitic microstructure. Two welds suffered from solidification cracking. The implications of these results for critical applications are discussed in the light of recent work on laser welding with wire feed which may offer some advantages.