Weld Toe
The area where the weld transitions into the base material. Special microstructures and chemical changes can occur here.
Physical-Chemical Mechanism of Action
During welding, the chemical compositions and crystal structure change near the weld transition. This leads to special microstructures like martensite or austenite, which differ from the surrounding areas.
Metallurgical Relevance & Welding Risks
An uneven weld transition can cause increased hardness and toughness, leading to cracks and wear. In addition, special microstructures like martensite can reduce formability and make the material more prone to hot cracking.
Workshop Practice & Action Instructions
To ensure a uniform weld transition, it is important to use an optimal welding temperature and controlled cooling steps. Avoid too fast cooling (t8/5 < 5 s) and too long cooling times (t8/5 > 25 s). For critical components, postweld heat treatment (PWHT) is recommended to produce homogeneous microstructures.