ASTM A967/A967M-13 pdf free.Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts.
This specification covers several different types of chemical passivation treatments for stainless steel parts. It includes recommendations and precautions for descaling, cleaning, and passivation of stainless steel parts. It includes several alternative tests, with acceptance criteria, for confirmation of effectiveness of such treatments for stainless steel parts.
5. Materials and Preparation for Passivation Treatments
5.1 The passivation treatments shall bc of one or more of the following types. The effectiveness of a particular treatment for a particular grade of stainless steel in a particular application is demonstrated by meeting the specified testing requirements:
5.1.1 Treatments in nitric acid solutions (see Section 6),
5. I .2 Treatments in citric acid solutions (see Section 7),
5.1.3 Treatments in other chemical solutions. including electroche inical treatments (see Section 8).
5. 1.4 Rinsing and neutralization (see Section 9), and
5.1.5 Post-cleaning treatments (see Section 10).
5.2 MiteriaIs:
5.21 The chemicals used for passivation treatments shall prodLice passivated surfaces that meet the requirements of one or more of the tests of this specification. Attention shall be given to maintaining adequate volume. concentration, purity. and temperature control appropriate Lu the site and amount of stainless steel to be treated.
5.2.2 The processor shall maintain a record with regard to concentration and temperature of the passivation solution sufficient to demonstrate that the specified passivation condi(ions were maintained for each lot of stainless steel parts processed. Such records shall be available for inspection when specified in the purchase order. The processor is not required to reveal the precise composition of proprietary chemical mixtures but shall maintain a unique identification of the mixture that will ensure its accurate representation for subsequent use.
8. Treatments in Other Chemical Solutions, Including
Eleetrochemical Treatments
S.1 It is recognized that the purpose of removal of all exogenous matter from a stainless steel surface, including the removal of free iron, can be accomplished by different media, with potential for benefits to be gained from use of proprietary skills and art, including proprietary passivation media. Such treatments may include externally applying an electrical potential on the stainless steel parts. as in the case of electropolishing. The suitability of such passivation treatments for use in meeting the requirements of this spccilication shall be determined by the capability of the processed parts meeting the specified test requirements.
8.2 Stainless steel parts shall be treated in a specified aqueous solution, with or without externally applied electrical potential, and maintained within a specified temperature range for a time sufficient for the processed parts to meet the specified test requirement.
8.3 Water Rinse—Immediately after removal from the passivating solution, the parts shall he thoroughly rinsed, using stagnant, countercurrent, or spray washes, singly or in combination, with or without a separate chemical treatment for neutralization of the passivation media (see Section 9), with a final rinse being carried out using water with a maximum total solids content of 200 ppm.