Cracking in welds is one of the most common defects that can weaken the joint strength and even lead to structural failure. One of the main causes of cracking is thermal stress resulting from rapid temperature changes during or after welding. Two effective methods to reduce these stresses are preheating and post-weld heat treatment (PWHT).
Preheating refers to heating the base metal prior to welding. It helps improve weld penetration, reduce moisture and hydrogen absorption, and prevent cracking caused by internal stresses.
On the other hand, post-weld heat treatment is a process carried out after welding, aimed at reducing residual stresses and stabilizing the metallurgical structure of both the weld metal and the base metal. This process is especially important when welding high-carbon steels, low-alloy steels, or when the structure is subject to high pressure.
When used together, preheating and post-weld heat treatment can significantly extend the service life of the welded component, minimize the risk of cracking, and ensure the final weld quality. Applying these techniques in accordance with industrial standards and under the supervision of a qualified welding engineer ensures the safe and reliable performance of welded joints.
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