Liquid Penetrant Inspection
A non-destructive method for determining the existence and extent of possible defects. A specially formulated liquid called penetrant is applied to the material surface where it seeps into any infraction, void or crack. The penetrant is then wiped clean and a developer is applied. Wherever the penetrant is found, it will appear as a red indication over the powdery white developer and clearly define the infraction. This “first line of defense” test works on all materials regardless of the composition and is generally considered an easy way to double check the surface integrity of your material. It also works on stainless steel and other nonferrous alloys where the magnetic particle inspection is not applicable.
Magnetic Particle Inspection
A non-destructive method for determining the existence and extent of possible defects in ferromagnetic materials. The material or part being inspected is magnetized. Finely divided magnetic particles, applied to the magnetized part are attracted to and outline the pattern of any magnetic-leakage fields created by discontinuities, cracks, voids or flaws. The ferromagnetic requirement limits this method to carbon and low-alloy steels rendering it useless on stainless steels and other nonferrous alloys.