Nitric Acid Passivation (ASTM A967 / AMS 2700)

Nitric acid passivation is the traditional method for removing free iron and restoring the corrosion resistance of stainless steel — specified where a drawing calls for a nitric process. Gleco passivates to ASTM A967 and AMS 2700 at our AS9100D and ISO 9001:2015 certified, ITAR Registered Texas plants.

AS9100D

ISO 9001:2015

ITAR Registered

Rowlett & McAllen, TX

📍 Available at: Rowlett, TX (Dallas–Fort Worth) & McAllen, TX (Rio Grande Valley)

Nitric Passivation Specifications

Governing specs	ASTM A967; AMS 2700 (Method 1, nitric); ASTM A380; QQ-P-35 (historical)
Nitric methods (A967)	Nitric 1–4 (varying concentration and temperature; some with sodium dichromate)
Acceptance tests	Water immersion, high humidity, salt spray, copper sulfate, free-iron (potassium ferricyanide-nitric)
Dimensional impact	None (no coating is applied)
Alloy note	Correct type selected for free-machining, high-carbon martensitic, and PH grades
Typical uses	Aerospace and defense stainless hardware, machined components, legacy nitric-specified parts

See also: passivation overview, citric passivation, nitric passivation.

FAQ

Nitric Passivation FAQ

What is nitric acid passivation?

Nitric acid passivation removes free iron and restores the chromium-oxide layer on stainless steel per ASTM A967 and AMS 2700. It is the traditional passivation chemistry and is specified where a drawing calls for a nitric method or dichromate-sealed treatment.

When is nitric specified over citric?

Nitric is chosen where a legacy or program specification requires it, and for certain higher-chromium and martensitic grades. Both meet ASTM A967 and AMS 2700 when the correct type is called out; if your drawing allows either, our chemists recommend the best fit.

What nitric types and methods do you run?

Nitric methods 1 through 4 per ASTM A967 (varying acid concentration and temperature, some with sodium dichromate), and Method 1 per AMS 2700, selected by alloy and drawing requirement.

How do you verify nitric passivation?

Per the practice specified on your drawing — water immersion, high humidity, salt spray, copper sulfate, or free-iron testing — supported by our on-site laboratories and documented with your certification package.

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Nitric Acid Passivation (ASTM A967 / AMS 2700)

Nitric Passivation Specifications

Nitric Passivation FAQ

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