Passivation of corrosion resistant steel in accordance with QQ-P-35, AMS-QQ-P-35, ASTM A967, AMS 2700
| Specification | Classification | |
| QQ-P-35 / AMS-QQ-P-35 | Types | |
| II | Medium temperature nitric acid solution with sodium dichromate additive. | |
| VI | Low temperature nitric acid solution. | |
| VII | Medium temperature nitric acid solution. | |
| VIII | Medium temperature high concentration nitric acid solution. | |
| AMS 2700 | Methods | |
| 1 | ||
| 2 | ||
| Types (for Method 1) | ||
| 1 | Low temperature nitric acid with sodium dichromate. | |
| 2 | Medium temperature nitric acid with sodium dichromate. | |
| 3 | High temperature nitric acid with sodium dichromate. | |
| 4 | 40% nitric acid for free machining steels. | |
| 6 | Low temperature nitric acid. | |
| 7 | Medium temperature nitric acid. | |
| 8 | Medium temperature, high nitric acid concentration. | |
| ASTM A967 | Treatments in Nitric Acid Solutions | |
| Nitric 1 | 20-25% by vol. Nitric Acid and 2.5±0.5 % by wt. Sodium Dichromate. Immersion time: 20 minutes min. Temp: 120-130⁰F (49-54⁰C) |
|
| Nitric 2 | 20-45% by vol. Nitric Acid Immersion time: 30 minutes min. Temp: 70-90⁰F (21-32⁰C) |
|
| Nitric 3 | 20-25% by vol. Nitric Acid Immersion time: 20 minutes min. Temp: 120-140⁰F (49-60⁰C) |
|
| Nitric 4 | 45-55% by vol. Nitric Acid Immersion time: 30 minutes min. Temp: 120-130⁰F (49-54⁰C) |
|
| Nitric 5 | Other combinations of temperature, time and concentration of Nitric Acid, with or without other chemicals including accelerants, inhibitors, or proprietary solutions, capable of producing parts that pass the specified test requirements. | |
| Treatments in Citric Acid | ||
| Citric 1 | 4-10% by weight Citric Acid Immersion time: 4 minutes min. Temp: 140-160⁰F (60-71⁰C) |
|
| Citric 2 | 4-10% by weight Citric Acid Immersion time: 10 minutes min. Temp: 120-140⁰F (49-60⁰C) |
|
| Citric 3 | 4-10% by weight Citric Acid Immersion time: 20 minutes min. Temp: 70-120⁰F (21-49⁰C) |
|
| Citric 4 | Other combinations of temperature, time and concentration of Citric Acid, with or without other chemicals to enhance cleaning, including accelerants, inhibitors, or proprietary solutions, capable of producing parts that pass the specified test requirements. | |
| Citric 5 | Other combinations of temperature, time and concentration of Citric Acid, with or without other chemicals to enhance cleaning, including accelerants, inhibitors, or proprietary solutions, capable of producing parts that pass the specified test requirements. Immersion bath to be controlled at a pH of 1.8-2.2. |
