Transverse cold cracking
Transverse cold cracks are right-angle fractures to the welding direction that occur during cooling. They are caused by diffusible hydrogen, a hardened microstructure, and high residual stresses.
Physical-Chemical Mechanism of Action
Transverse cold cracks occur when hydrogen diffuses into the metal and condenses at the grain boundaries during cooling. This causes local stresses that lead to fractures when hydrogen content is high and the microstructure is hardened.
Metallurgical Relevance & Welding Risks
Transverse cold cracks can cause severe mechanical stresses and damage the material. They often cause cracks that run parallel to the welding direction, significantly reducing the component's service life. The risk is particularly high in stiff steels with high hydrogen content and rapid cooling.
Workshop Practice & Action Guidelines
To prevent transverse cold cracks, degas the metal before welding. This can be done by high temperature or chemical methods. Also, prefer slower cooling and use low-hydrogen welding materials. For highly stressed components, normalize the microstructure after welding to relieve stresses.