Welding is a very energy intensive process and the thermal gradients that occur during welding can generate internal residual stresses in the metal. These unwanted stresses can contribute to distortion or corrosion in welded fabrications and castings and may even cause premature failure of components. Onsite stress releiving heat treatments for welds are used to eliminate these residual stresses by heating the metal and holding it at this temperature for a period of time which reduces them to acceptable levels. This is a critical step in the manufacturing of metal parts with tight tolerances and complex shapes as well as any welded or cast constructions that will be subject to heavy loads.

Is aluminium heat treated?

When welds are not properly treated, they remain under a tensile load from the restrained base materials which are trying to tear the weld apart. This condition is known as residual stress and it can cause a variety of problems from premature failure of products to reduction in load capacity and speed up fatigue and creep damage.

In most cases a post weld heat treatment is needed to achieve a satisfactory level of residual stresses and in some instances other thermal processes such as tempering are required to obtain a suitable metallurgical structure. These are often superimposed over a stress relieving operation to further control the pattern of residual stresses in a part and can be performed with resistance heated blankets, induction systems or in a furnace depending on the application.