If a part to be penetrant tested is first heated to high temperature, what may happen to the penetrant?

Heating a part prior to penetrant testing can significantly impact the behavior of the penetrant material. When a penetrant is applied to a hot surface, the increased temperature can lead to rapid evaporation of the penetrant. This occurs because the penetrant's boiling point is lower than the temperature of the heated part, causing it to vaporize quickly.

Rapid evaporation is a critical issue because it can prevent the penetrant from adequately filling defects or discontinuities in the surface being tested. If the penetrant evaporates before it has a chance to enter these flaws, it will not be able to perform its intended function of revealing subsurface defects.

Understanding this phenomenon is essential for ensuring successful penetrant testing. Appropriate procedures must provide guidance on temperature limits for parts being tested, considering the evaporation characteristics of the specific penetrant being used.