In welding, the Heat Affected Zone (HAZ) is a crucial area for preserving the quality of the base material, especially in high-strength steel types. During the production process, the microstructure of the base material is refined through thermal or mechanical (or even combined) processes, which gives the steel its strength.
However, in arc welding, high temperatures are generated in the zone adjacent to the weld due to the slow travel speed. When the temperature reaches around 700°C, grain growth occurs, causing the grains in the microstructure to re-grow, resulting in a loss of the base metal's quality characteristics. This critical zone is where "cold cracks" or "hydrogen cracks" can occur. To prevent this, PWHT procedures have been established.
Post Weld Heat Treatment (PWHT) procedures are post-welding treatments that involve heating and slowly cooling the welded material. The goal is to reduce internal stresses, modify the microstructure, and restore the properties of the weld metal. This improves the durability, integrity, and performance of the weld joints.
The benefits of laser welding for HAZ
Laser welding generates extremely high heat in minimal time, allowing for welding at extremely high travel speeds and significantly reducing the heat-affected zone to almost negligible levels. As a result, the base material retains its original quality, and the weld joint itself is even stronger than with arc welding.
Laser welding also brings advantages for aluminium or heat-crack-sensitive materials due to its limited heat input. The fine weld seams help limit width-to-height ratio cracks thanks to the cold welding process and high welding speed.
The importance of high-quality welding
The quality of weld joints should not be underestimated, as it not only affects their strength but also contributes to the aesthetic aspect of the welding appearance. Deep penetration at high welding speeds contributes to high-quality welding.
HAZ in welding: enhance your results
If you want to learn more about heat-affected zones in welding and how to improve the quality of your weld joints, we are here to guide you. Contact us for more information and tailored advice. Together, we can strengthen your welding processes and elevate the quality of your welding work to a higher level.