Liquid Penetrant Testing
Dye penetrant testing is an optical method for detecting surface cracks and defects. A colored liquid is applied to the cracks, which is made visible by a developer after cleaning.
Physical-Chemical Mechanism of Action
A colored or fluorescent liquid is sprayed under pressure into surface cracks of a material. This liquid is selected so that it is well absorbed by the metal structure and does not immediately flow away.
Metallurgical Relevance & Risks in Welding
Dye penetrant testing detects visible surface cracks and defects, such as cracks on the surface or under paint. This is especially important in areas with high safety requirements or for high-quality components.
Incorrect application or too weak a liquid can cause smaller cracks not to be made visible, leading to misunderstandings and potential defects in the product.
Workshop Practice & Instructions
1. Prepare the material: Remove all surface coatings such as paint or varnish.
2. Spray the colored liquid under pressure into the cracks and defects.
3. Allow the liquid some time to flow and remain in the cracks.
4. Clean the material with the developer according to the manufacturer's instructions.
5. Carefully inspect for visible bleed-out at the cracks.