Heat treatment aims to prevent or eliminate problems resulting from welding. The annealing of welds prevents stress in the material around the weld seam. Stresses in the material can unintentionally cause cracks in the steel. Annealing ensures that stress is kept to an absolute minimum. Read on to learn more about annealing welds and the benefits of this technique.
The process of annealing
Annealing occurs at the end of the welding process and is also referred to as post weld heat treatment (PWHT). It is done after the welding process to improve the properties of the weld. Depending on the material and usage of the workpiece, we work with different heat treatment procedures according to client standards.
During the welding process a high temperature is experienced in the weld and parent metals (Heat-Affected Zone – HAZ). Once the weld cools, a residual stress is formed. After the PWHT process is complete, a specific procedure will be performed to reduce these stresses to an acceptable level. This also helps to reduce any increased hardness levels and improves toughness and ductility to an acceptable level.
There are different types of heat treatments, each of which has its own application. The heat treatments have in common that they have a positive influence on the mechanical properties of the welded materials. Annealing is part of a heat treatment and knows different types of methods such as stress-relieving annealing, low-hydrogen annealing, normalizing annealing and so on.
Low-hydrogen annealing is often performed just after welding to prevent cracking. These cracks can arise from an excessive concentration of hydrogen in combination with a crack-sensitive hard structure and internal stresses in the heat-affected zone or weld. Stress relief annealing aims to reduce internal stresses caused by welding or cold working. Normalizing annealing is used to improve an inhomogeneous, coarse-grained structure, and solvent annealing serves to dissolve secretions present in the material to obtain a homogeneous structure.
Most of the work is carried out on site and varies from the treatment of pipe welding to the treatment of complete equipment, such as pressure vessels, reactors, etc. Delta Heat Services has developed a mobile system so that annealing can be carried out on location. The mobile system makes it possible to build a gas or oil-fired annealing furnace in any desired size in a very short period of time. The dimensions and possibilities are unlimited!
In addition to on-site implementation, Delta Heat Services has various ovens in which complete workpieces and pipe parts up to a length of 18 meters can be treated in their entirety. In addition to stress-relieving annealing, it is also possible to anneal to a normalizing temperature up to 1.200 ° C.
Your annealing specialist
Delta Heat Services mainly focuses on the execution of heat treatments for the industry. These heat treatments consist of preheating during welding and annealing treatments after welding. We offer a wide range of services and possibilities. We have the knowledge and the technology to offer you the heat treatment solution you are looking for.
Are you curious about the possibilities of Delta Heat Services or would you like to know more about the annealing process? Please contact us. We are happy to answer your questions and look at the possibilities together.