Shrinkage groove
Shrinkage groove is a depression on the weld surface caused by volume contraction during solidification. It can lead to destruction of the weld and component.
Physico-Chemical Mechanism of Action
During cooling of metals in welding, the material shrinks as it condenses from a liquid to a solid phase. This process leads to a volume contraction that is more pronounced at edges and surfaces than in the material's interior. The concentration of stress and pressure on these areas can cause the material to expand in the form of cracks or shrinkage.
Metallurgical Relevance & Risks in Welding
Shrinkage cavities can lead to destruction of the weld and the part. They increase stress in the weld, which can lead to cracks or hot cracks. Moreover, they impair the mechanical strength and appearance of the part.
Workshop Practice & Instructions
To avoid shrinkage cavities, it is important to ensure controlled cooling of the weld. This can be achieved by using cooling water or cooling gas. Cooling should be slow and uniform to minimize stress. For heavy metals like steel, it is especially important to ensure a sufficient cooling time of at least 10 minutes.