Lack of inter-run fusion
Lack of interlayer fusion occurs in multi-pass welds when slag is not completely removed or welding parameters are too low. This leads to lack of fusion between layers and can result in deterioration of mechanical properties and increased risk of hot cracking and porosity.
Physicochemical Mechanism of Action
In multi-pass welds, a layer of slag forms between the passes. If it isn't fully removed or the welding power is too low, lack of fusion between passes remains. This prevents a homogeneous bond and leads to uneven stresses.
Metallurgical Relevance & Welding Risks
A lack of interpass fusion can ruin the mechanical properties of the weld. The uneven stresses can cause hot cracks and porosity in the weld, which weakens the joint and shortens the part's service life.
Shop Practice & Action Items
To avoid lack of interpass fusion, make sure to remove all slag between passes. You can do this by careful cleaning and using the right welding process. The welding power must be high enough to get full fusion. If slag isn't removed or power is too low, the weld can open up unevenly and cause hot cracks and porosity.