Types of Post Weld Heat Treatment
Posted on 12-04-2024 03:36 PM
Post weld heat treatment (PWHT) is a process of heating metal components after welding to reduce residual stresses and to improve the properties of the welded material. It is an important part of many fabrication processes, especially in those industries dealing with large and complex structures.
The type of PWHT that is used depends on the application, as well as the material being worked upon. There are three main types of PWHT: re-heat treatments, stress relieving and tempering. Re-heating treatments involve reheating the entire welded area until it reaches a specified temperature, while stress relieving involves only heating up certain areas of the weldment to release existing residual stresses. Tempering entails reheating the weldment to a lower temperature than re-heating for a specified period of time to soften it up.
Transition: Each type has its own benefits and drawbacks.
Re-heat treatments are most commonly used when high strength or hardness is desired in a component or structure; this includes applications such as pressure vessels, boilers and pipelines. The downside to this type of PWHT is that it can lead to increased distortion if not done correctly, as well as over-stressing some parts due to uneven heat distribution across the whole structure or component.
Stress relieving can help reduce cracking by decreasing residual stresses; however it also can affect mechanical properties like tensile strength and yield point if done incorrectly or excessively. Tempering has benefits such as improving ductility without reducing strength too much; however it also can be detrimental if done wrong due to parts becoming too soft! As you can see, each type of PWHT carries its own risks - so care must be taken when choosing which one is right for your project!