Shrinkage Residual Stresses
Shrinkage residual stresses arise from uneven volume changes during phase transition or cooling. They lead to mechanical loads and can cause cracks.
Physical-Chemical Mechanism of Action
Shrinkage residual stresses occur when parts of a material cool at different rates or expand/contract during phase transformation (e.g., from liquid to solid). These uneven volume changes create mechanical stresses within the material structure.
Metallurgical Relevance & Welding Risks
Shrinkage residual stresses can cause cracks and fracture points in the weld, especially if not properly managed. They increase susceptibility to hot cracking and can impair the material's mechanical strength.
Shop Practice & Action Guidelines
To minimize shrinkage residual stresses, controlled cooling is essential. This can be achieved by using stress-relieving methods or performing post-weld heat treatment. For steels with high carbon content, it's crucial to ensure slow cooling to reduce the risk of martensite formation and thus cracking.