Ultrasonic Cavitation
Definition
High-frequency pressure waves that collapse cavitation bubbles preferentially at high-energy surface zones; an alternative physical restoration method for stainless-steel and titanium substrates.
- Mechanism
- High-frequency pressure waves collapsing cavitation bubbles
- Effect location
- High-energy surface zones preferentially
- Application
- Restoration of erased serial numbers
- Substrates
- Stainless steel and titanium
Common questions
Why is ultrasonic cavitation used as an alternative to chemical etching for serial number restoration?+
Some stainless-steel and titanium alloys resist chemical etchants effective on mild steel, so cavitation offers a physical route that preferentially attacks the strain-hardened metal beneath a stamped and then ground-off serial number without relying on an acid that may not work on that alloy.
How does cavitation reveal a serial number that was physically ground away?+
Stamping deforms the metal's crystal structure to a depth beyond the visible impression, and cavitation bubbles collapsing at these higher-energy, strain-hardened zones erode them faster than the surrounding undisturbed metal, gradually re-exposing the digit pattern as a visible relief.
Related terms
- ASTM E2885-13
- ASTM International standard practice for restoration of obliterated vehicle identification numbers; the reference protocol for VIN casework in US and internationally aligned...
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- Cold-Working Stress Field
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- Davis Reagent
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- Electrolytic Etching
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- Fry's Reagent
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- INTERPOL iARMS
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- Magnetic Particle Inspection (MPI)
- A non-destructive testing method that reveals magnetic-domain contrast between cold-worked and unstressed zones in ferromagnetic metals using a ferrofluid under UV illumination;...
- Neutron-Induced X-Ray Fluorescence (NIXRF)
- A synchrotron-based method using neutrons to probe deep obliterations; can detect digit geometry buried several millimetres beneath a machined surface, entirely non-destructively.
- Profilometry
- White-light interferometry or confocal laser scanning to detect nanometre-scale height differences on a metal surface; can reveal topographic ghost images of obliterated...
- Turner's Reagent
- A ferric chloride solution used to etch copper, brass, and cuprous alloy substrates; the high-potential Fe3+ ion preferentially oxidises the cold-worked zone.