TWI Industrial Member Report Summary 156/1981
By T G Davey
The microstructure and toughness of the heat-affected zone (HAZ) of single-pass submerged-arc welds were examined at three levels of arc energy (1.5, 3.0 and 6.0kJ/mm). Each arc energy was achieved in several different ways by altering the welding current, voltage and travel speed. The 25mm thick steels used contained Al and/or Nb additions. Microstructure was assessed by point counting, grain size and hardness measurements, and toughness by the crack opening displacement (COD) test. A complex relationship was found, but the most important factor controlling HAZ structure and toughness in a given steel at the thickness employed was found to be the arc energy. At a given arc energy, changes in welding parameters had no major effects.