Development of an equation for aluminum alloys to determine the width of the zone affected by welding

Canadian Standards Association standard CAN3-S157-M83 (R2002), Strength design in aluminum, requires that the zone affected by welding be taken to extend a distance of 25 mm each side from the centre of the weld. The objective of this investigation was to develop an equation to determine the width of the zone affected by welding adjacent to a weld for a given set of parameters. One hundred and twelve weldment specimens were fabricated using five alloys, seven material thicknesses, and different heat fluxes. Hardness was measured in the zone affected by welding to determine the width and hardness gradient. The investigation has determined that the width of the zone affected by welding depends on several parameters. The heat flux has the greatest influence on the width of the zone affected by welding. Factors such as plate thickness, thermal conductivity, and multipass welding also have an effect on the width of the zone affected by welding. It is concluded based on this investigation that the width of the zone affected by welding can be reduced substantially in welded connections fabricated using properly selected weldable aluminum alloys and thicknesses and an automatic process mode with a low and uniform heat flux.Key words: aluminum alloys, hardness, heat flux, welding.