Ultrasonic surface impact treatment
Ultrasonic surface hammering transfers high-frequency vibrational energy to a tool, resulting in intensive cold working of the surface layer and increasing fatigue strength.
Physical-Chemical Mechanism
Ultrasonic surface peening uses high-frequency sound waves (typically between 20 kHz and 5 MHz) to transfer energy to a tool. This energy causes the tool surface to work-harden faster and more intensely than conventional methods.
Metallurgical Relevance & Welding Risks
The cold working of the surface layer increases hardness and fatigue strength, leading to improved service life and higher load-bearing capacity. However, excessive work hardening can lead to cracking risk or serious material changes if the energy settings are not correct.
Shop Practice & Action Items
To use ultrasonic surface peening effectively, follow these steps:
• Energy setting: Set the energy so that you get visible surface hardening without over-treating the material.
• Temperature control: The tool should be cold before peening to ensure uniform hardening.
• Duration and frequency: Adjust peening time and frequency based on material and application. A rule of thumb is that 10 to 30 seconds per cm² of surface is sufficient.