What types of materials are generally unsuitable for Liquid Penetrant Testing?

Liquid Penetrant Testing (PT) is most effective on non-porous materials that can retain the penetrant and allow for clear indications of surface defects. High-temperature alloys and porous materials are generally unsuitable for PT due to their inherent properties.

Porous materials can absorb the penetrant, thereby preventing adequate performance of the test. This absorption leads to false results, as the penetrant may not be properly drawn out from defects due to the material’s porosity. Similarly, high-temperature alloys, depending on their composition and finishing, may also pose challenges, as they can have surface conditions or temperatures that negatively affect the penetrant's ability to be drawn into surface flaws or be removed effectively.

In contrast, while glass and plastics are often not ideal candidates for PT, they can sometimes be inspected effectively under specific conditions. Metal composites can also be tested, but their suitability depends on the matrix and filler materials used. Therefore, option B accurately identifies materials that are generally unsuitable for PT due to their physical properties that interfere with the detection of discontinuities.