Investigation of the influence of welding on 6351-T6 aluminum alloy adjacent to a joint.

摘要

Increased welding speeds have reduced the heat input in the parent metal, thus reducing the width of the heat-affected zone. The present CSA Standard CAN3-S157-M83 "Strength Design in Aluminum", requires that the zone affected by a weld be taken to extend a distance of 25 mm each side from the centre of the weld.; The objective of this experimental investigation was to determine the width of the heat-affected zone and the strength of the metal across the heat-affected zone adjacent to the weld.; Ninety-four specimens, parent and welded metal, were tensile tested, 33 specimen bars and plates were hardness tested and 46 cantilevered assemblies were flexure tested. The ultimate tensile stresses and the hardness numbers from the testing results were used to determine the width and strength of the heat-affected zone.; This investigation has determined that the width of the heat-affected zone for a given weld size, alloy, welding procedure and heat input decreases with the increase in the plate thickness. Also, the average strength of the metal in the heat-affected zone was found to be higher than the CSA Standard requirements.; Based on this investigation, it is concluded that a 6351-T6 aluminum alloy welded using an automatic welding operation, with a low and uniform heat input and with the use of a properly designed welding procedure, the width of the heat-affected zone can be reduced and the average strength of the metal in the heat-affected zone increased.