Pre Heating Services

Thermal stresses occur as molten weld pools cool at which point cracking can occur both during and after welding. Moreover, the colder parent or base metal resists the inevitable contraction of the weld metal. In some instances heavy wall materials and aluminum alloys with higher thermal conductivity can act as a heat sink, drawing heat away from a weld and cooling at an accelerated rate. If moisture is present at a welded joint, the high heat of the welding arc will break the water down into its elements, hydrogen and oxygen.

The hydrogen by-product easily dissolves into the weld metal and causes weld porosity during weld solidification. During and after completing of the welding process, both the weld pool and the heat affected zone (HAZ) can harden and crack when cooling at a rapid pace. Pre heat treatment is used to prepare the base metal work area so as to improve the integrity of the weld or machining process by raising the temperature gradually thereby improving ductility in advance of the work taking place. This enables the higher temperature area to respond more effectively to the weld or machining process.