Stainless Steel Passivation Services for Corrosion Resistance & Surface Integrity
MIL performs precision passivation to remove surface contaminants and restore the natural corrosion-resistant oxide layer of stainless steel and other corrosion-resistant alloys. Our processes meet strict aerospace, defense, medical, and industrial specifications to ensure long-term durability and reliability.
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Purpose-Built Passivation for High-Performance Metal Components
Passivation is a chemical treatment that enhances the corrosion resistance of stainless steel by dissolving free iron and contaminants that can accumulate during machining or handling. Without proper passivation, stainless steel is significantly more vulnerable to rust, staining, and premature failure—especially in demanding environments.
MIL uses controlled nitric and citric passivation chemistries based on alloy requirements and specification standards to ensure optimal results.
Passivation Highlights
- Restores corrosion-resistant oxide layer
- Removes embedded iron and machining contaminants
- Improves longevity in harsh operating environments
- Fully compliant with MIL, AMS, ASTM, and OEM specifications
- Ideal for sensitive or tight-tolerance components
Optional post-process testing available per spec requirements
How the Passivation Process Works
Step 1 — Cleaning & Pre-Treatment
Parts are cleaned to remove oils, cutting fluids, and debris that may interfere with the passivation reaction. Pre-cleaning ensures even chemical exposure.
Step 2 — Chemical Passivation
Components are immersed in a nitric or citric acid solution tailored to the specific alloy. The solution dissolves free iron from the surface while allowing chromium-rich oxide to form naturally.
MIL applies strict controls to prevent:
- Flash attack
- Dimensional changes
- Over-etching
- Hydrogen absorption
Step 3 — Rinsing & Neutralization
After treatment, parts are neutralized and rinsed thoroughly to stop the reaction and prevent staining or chemical residues.
Step 4 — Inspection & Optional Validation Testing
Based on specification, MIL may perform one or more passivation verification tests:
- Copper sulfate test
- High humidity test
- Salt fog test
- Potassium ferricyanide (Feroxyl) test
All results are documented when required.
Why Work With MIL for Passivation Services?
Precision Processing for Critical Stainless Steel Components
Not all stainless steels passivate the same way. Certain grades (e.g., 303, 416, 420, 440) are prone to flash attack or staining. MIL’s technicians adjust chemistries, dwell times, and pre-treatments to prevent these issues.
Expertise Across Aerospace, Defense & Industrial Standards
MIL regularly performs passivation to:
- AMS 2700
- ASTM A967
- Boeing, Lockheed Martin, and other OEM specifications
- Nadcap-certified quality requirements
Integrated Multi-Process Workflows
Passivation is often paired with:
- Ultrasonic cleaning
- Electropolishing
- NDT / FPI
- Plating
- Conversion coatings
With one-stop processing, MIL minimizes risk and accelerates lead times.
Protecting High-Value, Tight-Tolerance Components
Our controlled process ensures no dimensional changes, surface degradation, or loss of critical fit.
Applications & Industries Served
Component Types
- Precision machined stainless steel parts
- Medical and laboratory instrumentation
- Aerospace fasteners and assemblies
- Hydraulic and pneumatic components
- Electronic housings and hardware
- Corrosion-prone surfaces exposed to harsh environments
Industries
- Aerospace & defense
- Space systems
- Medical devices
- Industrial manufacturing
- Energy & power systems
- Semiconductor and instrumentation
Frequently Asked Questions About Passivation
Primarily stainless steels (200, 300, 400 series and PH grades). Some nickel and cobalt alloys may also be passivated depending on spec requirements.
No. Passivation removes free iron and contaminants but does not build a coating or meaningfully alter dimensions.
Electropolishing removes a measurable amount of metal and smooths the surface. Passivation does not remove bulk material—it simply restores corrosion resistance.
Some stainless steels contain sulfur or inclusions that react aggressively with nitric acid. MIL uses modified processes and A-A-A (Alkaline–Acid–Alkaline) cycles to prevent damage.
Some specifications require copper sulfate, salt fog, humidity, or Feroxyl testing to verify passivation effectiveness. MIL performs these tests when required.
Yes. Many components undergo passivation immediately before or after FPI, cleaning, or other finishing workflows.
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Fast, accurate estimates for single-process or multi-process finishing workflows.
Unsure which passivation chemistry or validation test applies? Our team can guide you.
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