AMS 2700 Revision E, “Passivation of Corrosion Resistant Steels,” has just been released. The new edition replaces AMS 2700 Revision D which was released back in July of this year. The specification covers the requirements for a process to assure removal of free iron or other less noble contaminants from the surfaces of corrosion resistant steel parts.
There are two passivation methods covered by AMS 2700E — Passivation in Nitric Acid and Passivation in Citric Acid.
For the first method, 8 types may be specified:
- Low Temperature Nitric Acid with Sodium Dichromate
- Medium Temperature Nitric Acid with Sodium Dichromate
- High Temperature Nitric Acid with Sodium Dichromate
- 40% Nitric Acid for Free Machining Steels
- Anodic, for High Carbon Martensitic Steels
- Low Temperature Nitric Acid
- Medium Temperature Nitric Acid
- Medium Temperature, Nigh Nitric Acid Concentration
The processes defined in this specification have been used typically to dissolve metallic elements from the surfaces of corrosion resistant steels to improve their corrosion resistance, but usage is not limited to such applications.
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