Thermal Shock in Melt Pool
Thermal shock during welding: The high-energy beam hitting cold steel creates a severe stress state that can lead to local distortion and possible cracking.
Physicochemical mechanism of action
A high-energy welding beam (e.g., laser or electron beam) creates a strong stress state when it hits cold steel. This causes local deformation and can lead to microscopic cracks in the material.
Metallurgical relevance & welding risks
A thermal shock that is too severe can damage the material's microstructure, resulting in reduced toughness and a higher risk of cracking. This can be a problem especially for thick parts or steels with low stress-relief capability.
Workshop practice & action instructions
To minimize thermal shock, heat the steel slowly to melting temperature before welding. Cooling steps should be controlled and slow. For thick parts or steels with low stress-relief capability, it is advisable to perform additional post-weld heat treatment.