Portable ultrasonic flaw detectors are widely used in metal material testing, weld evaluation, pipeline inspection, and composite material analysis due to their portability and efficiency. For different scenarios, it is necessary to optimize the detection effect by adjusting parameters such as probe type, frequency, gain, and scanning mode.

1. Internal defect detection of metal materials

For thick metal plates or castings, choose a low-frequency (1-2.5MHz) straight probe and use the strong penetration of low-frequency ultrasonic waves to detect deep defects (such as pores and inclusions). For thin metal sheets (such as aluminum plates), a high-frequency (5MHz) probe is used to improve resolution and identify shallow cracks. The initial gain setting is based on the clear visibility of the bottom wave, and a straight or grid path is used during scanning to ensure full thickness coverage.

2. Weld quality assessment

Weld seam inspection requires the use of an angle probe (such as K2 or K2.5) to cover the weld seam and heat affected zone by adjusting the refractive angle. Adopting zigzag or cross scanning, with a speed controlled between 50-100mm/s to avoid missed detections. Set the gate locking weld area and quantify the defect size using DAC curve (distance amplitude correction curve) to ensure compliance with standards (such as ISO17637).

3. Pipeline inspection and corrosion monitoring

For curved pipes, select curved wedges that match the pipe diameter to ensure a tight fit between the probe and the pipe wall. Using spiral scanning method combined with high-frequency probe (5MHz) to detect wall thickness changes and corrosion pits. The gain needs to be adjusted according to the material of the pipe wall (such as carbon steel, stainless steel) to avoid signal overload or attenuation.

4. Composite material delamination and debonding detection

Composite materials (such as carbon fiber reinforced resin) require the use of square wave excitation mode to enhance signal amplitude due to significant attenuation, while selecting low-frequency probes (0.5-1MHz) to improve penetration. When scanning, slow linear movement is used, combined with B-scan imaging function, to visually display the layering position and range.