PreheatingWhen a weld is made, the parent material close to the weld itself undergoes some changes, due, in part, to the heat treatment imposed on the material by the welding operation. However, there are also other forms of heat treatment that may be applied at various stages in the welding operation. Such heat treatment associated with a welding cycle can be divided into three distinct stages, namely, 'Preheating', 'Interpass Temperature' and 'Post Weld Heat Treatment' Preheating is a process that is applied to the parent material of a component prior to welding. There are often different metallurgical reasons why preheating is needed and the most common of these are discussed.
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