5 Nondestructive Testing Methods For Steel

The nondestructive testing of steel mainly involves ray testing, ultrasonic testing, magnetic particle testing, penetration testing and eddy current testing.

 1. Radiographic Detection (RT)
X-ray testing refers to the non-destructive testing method that uses X-ray or gamma ray to penetrate the specimen and uses film as the equipment for recording information. This method is the most basic and widely used non-destructive testing method.

2. Ultrasonic Detection (UT)
Ultrasonic testing is suitable for nondestructive testing of metal, nonmetal and composite materials. It can detect the internal defects of the specimen within a wide thickness range. For metal materials, can detect the thickness of 1 ~ 2mm thin wall pipe and plate, can also detect several meters long steel forgings; Moreover, the defect location is more accurate and the detection rate of area defects is higher. High sensitivity, can detect the internal size of the specimen is small defects; And the detection cost is low, the speed is fast, the equipment is light, harmless to the human body and the environment, the field use is more convenient.

3. Magnetic Particle Detection (MT)
Principle of magnetic particle detection is magnetized ferromagnetic material and workpiece, but because of the discontinuity, the magnetic field lines on the surface of the workpiece surface and near local distortion and a leakage magnetic field is generated, adsorption on the surface of the magnetic powder and magnetic marks visible form in the right light visual, showing the location, shape and size of discontinuity.

4. Penetration Testing (PT)
The principle of penetration detection is that after the surface of the part is coated with permeant containing fluorescent dye or colored dye, under the action of capillary, after a period of time, the permeable liquid can penetrate into the surface opening defects; After removing the surface excess penetrant, painted on the parts surface imaging agent again, also, under the action of capillary, imaging agent will attract defects in penetrants, penetrating fluid flow back into the imaging agent, in a certain light (uv light or white light), defect penetrant traces are reality, (yellow-green fluorescence or bright red), Thus, the morphology and distribution of defects are detected.

5. Eddy Current Testing (ET)
Eddy current testing places a coil with alternating current on a metal plate or outside a metal tube under test. At this time, an alternating magnetic field will be generated in and around the coil, resulting in a vortex-like induced alternating current in the specimen, called eddy current. The distribution and size of eddy current are not only related to the shape and size of the coil and the size and frequency of the AC current, but also depend on the conductivity, permeability, shape and size of the specimen, the distance from the coil and whether there are cracks on the surface.