Five detection methods of surface defects of square tube

There are five main detection methods for surface defects of Steel Square Tube:

(1) Eddy current detection
There are various forms of eddy current detection, commonly used conventional eddy current detection, far-field eddy current detection, multi-frequency eddy current detection and pulse eddy current detection, etc. Using eddy current sensors to sense the metal, the different types and shapes of defects on the surface of the square tube will produce different types of signals. The advantages are high detection accuracy, high detection sensitivity, fast detection speed, the ability to detect the surface and subsurface of the pipe to be detected, and is not affected by impurities such as oil on the surface of the square tube to be detected. The disadvantage is that it is easy to determine the non-defective structure as a defect, the false detection rate is high, and the detection resolution is not easy to adjust.

(2) Ultrasonic detection
The use of ultrasonic waves into the object when encountering defects, part of the sound wave will produce a reflection, the transmitter and receiver can analyze the reflected wave, it can be exceptionally accurate to measure the defects. Ultrasonic detection is commonly used in forging detection, detection of high sensitivity, but not easy to check the complex shape of the pipe, the requirements of the inspection of the surface of the square tube has a certain degree of finish, and the need for coupling agent to fill the gap between the probe and the surface to be checked.

(3) magnetic particle detection
The principle of magnetic particle detection is to realize the magnetic field in the square tube material, according to the interaction between the leakage field at the defects and the magnetic powder, when there is a discontinuity or defects on the surface and near surface, then the magnetic lines of force at the discontinuity or defects in the local aberration generates the magnetic poles. The advantages are low investment in equipment, high reliability and intuition. The disadvantages are high operating costs, can not be accurately classified defects, detection speed is low.

(4) infrared detection
Through the high-frequency induction coil, an induction current is generated on the surface of the Square Tube Steel, and the induction current will cause the defective area to consume more electric energy, causing the local temperature to rise, and the local temperature is detected by infrared light to determine the depth of defects. Infrared detection is generally used for defect detection on flat surfaces and is not suitable for detecting metals with uneven surfaces.

(5) Magnetic leakage detection
The magnetic leakage detection method of square tube is very similar to the magnetic particle detection method, and the scope of application, sensitivity and reliability are stronger than the magnetic particle detection method.