False indication
False indication: An erroneous test indication resulting from part geometries, contamination, or magnetization spots, not caused by material flaws. Correct identification prevents unjustified rejection.
Physical-Chemical Mechanism of Action
A false indication is caused by reflection or absorption of radiation that is not directly related to material defects. For example, a magnetic indication may be caused by magnetic particle clusters or contamination.
Metallurgical Relevance & Risks in Welding
A false indication can lead to unjustified rejects because it is interpreted as a material defect. This costs time and material. It can also cause misunderstandings in the production chain.
Workshop Practice & Procedures
To correctly identify a false indication, take the following steps:
1. Check the part geometry for possible sources of reflection or absorption.
2. Remove contamination and re-test.
3. Use magnetization tests to identify magnetic particle clusters.
4. Compare the indication with known patterns of material defects.