GB/T 38811-2020 in English

Standard technical background

With the widespread application of large metal components in aerospace, rail transit and other fields, the problem of deformation and cracking caused by residual stress in welding and assembly has become increasingly prominent. Traditional heat treatment methods have defects such as high energy consumption and large deformation. As an emerging non-destructive stress control technology, the acoustic beam control method uses piezoelectric ceramic transducers to generate directional ultrasonic waves to achieve precise stress control.

Core principle analysis

Based on the energy interaction mechanism between elastic waves and residual stress inside the material: When 10-40kHz ultrasonic waves are transmitted into the material through the coupling agent, its wave energy can change the lattice distortion energy, promote dislocation reorganization and thus reduce residual stress. The key advantages are:

• Directionality: Directional propagation of sound beams is achieved through wedge design
• Penetrating: Can act on surfaces and internal 50mm depth
• Controllability: Energy input and action time can be precisely adjusted

Equipment system composition

Control mode comparison

Key points for implementation

According to the requirements of Chapter 6 of the standard, special attention should be paid to:

• Coupling quality: Use high-temperature blue oil to ensure that the sound energy transmission rate is greater than 90%
• Temperature monitoring: The surface temperature rise should be controlled within 80℃
• Parameter optimization: 20kHz/15min processing cycle is recommended for carbon steel
• Effect verification: CRL wave detection and comparison is carried out according to GB/T32073