Post Weld Heat Treatment (PWHT)
Post Weld Heat Treatment (PWHT) is an essential process applied after welding to enhance the mechanical and chemical properties of welded structures.
Welding induces residual stresses that can cause long-term distortions, especially in complex or large structures. This process is critical as it addresses the residual stresses and hardening that occur in the heat-affected zones due to varying carbon content.
During welding, the metals undergo solidification and melting, resulting in residual stresses that can approach the yield strength of the base material. PWHT is designed to mitigate these stresses, reducing the risk of brittle fracture and enhancing material strength and hardness. Stress relieving and post-heating are the most commonly utilized PWHT procedures.
PWHT not only improves resistance to brittle fracture but also ensures the structural integrity and longevity of the weldment. The application, code requirements, and service environment determine the necessity for PWHT, making it a crucial step in maintaining the quality and reliability of welded structures. This process is indispensable in various industries, ensuring that welded components meet stringent safety and performance standards.