Laser-assisted gas metal arc welding of 25-mm-thick HY-80 plate

Laser-assisted gas metal arc welding of HY-80 steel was investigated. The effect of welding parameters was studied and optimum welding conditions were identified. Welding using Lincoln LA-100 wire on 25-mm-thick HY-80 plate with a four-pass technique, a double 45-deg groove preparation, 9.5 mm deep with no root opening, a heat input of 1.6 kJ/mm and a 50% Ar-50% He gas shield produced a predominately martensitic weld metal microstructure. An acicular ferrite weld metal microstructure could not be produced for any set of processing conditions investigated. This is believed to be a result of the high levels of dilution. The toughness of the laser-assisted gas metal arc welds was assessed with dynamic tear testing and explosion bulge testing. Toughness was found to be low but highly variable. Optimum electrode chemistry would probably allow the toughness to be improved.