What is the proper stress relieving practice for aluminum welds?
When welding, the operator sets up residual stresses around the vicinity of the weld because the molten material shrinks as it solidifies. Further, when the operator takes this welded structure and begins to remove material by machining, it tends to distort and create dimensional instability. To avoid this in steel, operators perform stress relieving by heating the material hot enough to allow the aluminum atoms to move around. For steel, the stress relieving temperature is approximately 1050 F to 1100 F, but for aluminum, the proper stress relieving temperature is 650 F. This means that in order for post weld stress relief on aluminum to be effective, the material will have to be heated to a temperature where mechanical properties will be lost. For this reason, post weld stress relief is not recommended for aluminum.
