MAGNETIC TESTING (MT)
The Magnetic Method facilitates the detection of most dangerous surface and subsurface discontinuities:
- fatigue, forging, grinding and hardening cracks
- welding cracks
- cold shuts
- forging laps
- non-metal inclusions (holes)
This method involves magnetising the tested element to detect the magnetic field of scatter which occurs in the place where the discontinuity arises. This method is only applicable to the ferromagnetic structures or those plastic processed, welded or thermally treated (e.g. vessel plating, shafts, axles, pivots, gear transmissions, etc). The magnetic-particle testing enables the detection of open surface flaws and subsurface ones down to about 3 mm depth. Unlike the liquid penetrant method, the magnetic testing can be done to facilities bearing coats of paint, however, not thicker than 40 μm (e.g. structures with corrosion protection ground coat).