Macroscopic Residual Thermal Stresses
Thermal residual stresses of the first kind arise from uneven thermal expansion and contraction of metal parts at different temperatures. They lead to macroscopic stresses that can deform or crack components.
Physical-Chemical Mechanism of Action
Uneven cooling of metal parts creates first-order thermal residual stresses. The surface cools faster than the core, leading to different degrees of expansion and causing stress in the material.
Metallurgical Relevance & Welding Risks
These stresses can lead to unwanted part distortion or cracking. They impair the mechanical properties of the material and can cause hot cracks or weld distortion if not handled properly.
Shop Practice & Action Guidelines
To minimize first-order thermal residual stresses, uniform cooling is essential. Use protected welding processes and avoid rapid cooling. For steel parts with high carbon content (e.g., hardened plate), continuous cooling after welding is especially important to reduce stress and prevent cracking.