Surface Finish · Chemical Treatments
Passivation
Chemical hygiene for stainless: strips embedded iron so the steel can be as stainless as advertised.
Process specifications
| Parameter | Value |
|---|---|
| Process group | Chemical Treatments |
| Coating thickness | No coating — a sub-0.1 µm passive chromium-oxide layer is chemically rebuilt; embedded free iron is dissolved. |
| Tolerance impact | No dimensional change — all drawing tolerances apply unchanged. Safe on finished precision features, threads and sealing faces. |
| Corrosion rating | Restores the alloy’s intrinsic corrosion resistance (verified per ASTM A967 copper-sulfate or salt-spray test); adds nothing beyond it. |
| Appearance | No visible change — the part simply arrives cleaner. |
⚠ Not suitable for
Carbon and alloy steels (the chemistry does nothing for them — they need plating or coating); rescuing an under-specified alloy (passivated 304 still fails in chloride service where 316L is required); parts needing measurable smoothing or brightening (that is electropolishing).
Works on these materials
Typical applications
- Medical and surgical components (specified by default)
- Food and beverage contact parts
- Marine stainless hardware
- Aerospace fasteners and fittings
Related engineering guides
stainless steel 316L CNC machining
Stainless Steel 316L CNC Machining: Marine, Medical and Chemical Applications
A guide to CNC machining 316L stainless steel parts with passivation, corrosion requirements, tolerance and inspection considerations.
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CNC Machining for Pharmaceutical Machinery: Hygienic Parts, 316L and Documentation
Sourcing guide for CNC machined pharmaceutical production machinery parts: hygienic design, 316L and electropolishing, FDA-compliant polymers and batch documentation.
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Medical Device Machining: The Inspection and Documentation Package
What a medical CNC supplier should ship with the parts: CMM reports, FAI, CoC, material certificates, lot traceability and how to specify them at RFQ.
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