In order to study welding technology with higher heat input for super thick plates

the double-wire

three-wire and fourwire submerged arc welding experiments were carried out for steel plates of E36 W with thickness of 50 mm and 80 mm. The welded joints were tested by tensile and impact test. The experimental result shows that the mechanical properties of the joint after multi-wire submerged arc welding meet the requirements of marine engineering steels. The relative low impact toughness was exhibited in the weld metal. As the number of wires increases

the content of pre-eutectoid ferrite in the weld increases

and the grain size increases

which resulting in the decreasing of impact toughness. In the same welding process

the content of pre-eutectoid ferrite in 80 mm thick plate welds is more

and the grain size is larger

which resulting in the impact toughness decreasing.