1、Designation: A967 052Standard Specification forChemical Passivation Treatments for Stainless Steel Parts1This standard is issued under the fixed designation A967; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last rev
2、ision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1NOTESection 6.1.1.1 was editorially corrected in July 20
3、07.2NOTESection references were editorially corrected in Section 22.1 in March 2010.1. Scope*1.1 This specification covers several different types ofchemical passivation treatments for stainless steel parts. Itincludes recommendations and precautions for descaling,cleaning, and passivation of stainl
4、ess steel parts. It includesseveral alternative tests, with acceptance criteria, for confirma-tion of effectiveness of such treatments for stainless steel parts.1.2 Practices for the mechanical and chemical treatments ofstainless steel surfaces are discussed more thoroughly inPractice A380.1.3 Sever
5、al alternative chemical treatments are defined forpassivation of stainless steel parts. Appendix X1 gives somenonmandatory information and provides some general guide-lines regarding the selection of passivation treatment appropri-ate to particular grades of stainless steel. It makes no recom-mendat
6、ions regarding the suitability of any grade, treatment, oracceptance criteria for any particular application or class ofapplications.1.4 The tests in this specification are intended to confirm theeffectiveness of passivation, particularly with regard to theremoval of free iron and other exogenous ma
7、tter. These testsinclude the following practices:1.4.1 Practice AWater Immersion Test,1.4.2 Practice BHigh Humidity Test,1.4.3 Practice CSalt Spray Test,1.4.4 Practice DCopper Sulfate Test,1.4.5 Practice EPotassium FerricyanideNitric Acid Test,and1.4.6 Practice FFree Iron Test.1.5 The values stated
8、in inch-pound units are to be regardedas the standard. The SI units given in parentheses are forinformation only.1.6 The following precautionary caveat pertains only to thetest method portions, Sections 14 through 18 of this specifica-tion: This standard does not purport to address all of the safety
9、concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2A380 Practice for Cleaning, Descaling,
10、and Passivation ofStainless Steel Parts, Equipment, and SystemsB117 Practice for Operating Salt Spray (Fog) ApparatusB254 Practice for Preparation of and Electroplating onStainless Steel2.2 Federal Specification:3QQ-P-35C Passivation Treatments for Corrosion-ResistantSteels3. Terminology3.1 Definiti
11、on of Term Specific to This StandardIt isnecessary to define which of the several commonly useddefinitions of the term passivation will be used in thisspecification. (See Discussion.)3.1.1 DiscussionStainless steels are autopassivating in thesense that the protective passive film is formed spontaneo
12、uslyon exposure to air or moisture. The presence of exogenoussurface contamination, including dirt, grease, free iron fromcontact with steel tooling, and so forth, may interfere with theformation of the passive film. The cleaning of these contami-nants from the stainless steel surface will facilitat
13、e the spon-taneous passivation by allowing the oxygen uniform access tothe surface. The passive film may be augmented by chemicaltreatments that provide an oxidizing environment for thestainless steel surface.3.1.1.1 In this specification, passivation, unless otherwisespecified, is defined as the ch
14、emical treatment of a stainless1This specification is under the jurisdiction of ASTM Committee A01 on Steel,Stainless Steel and Related Alloys and is the direct responsibility of SubcommitteeA01.14 on Methods of Corrosion Testing.Current edition approved Sept. 1, 2005. Published September 2005. Orig
15、inallyapproved in 1996. Last previous edition approved in 2001 as A967 011. DOI:10.1520/A0967-05E01.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Do
16、cument Summary page onthe ASTM website.3Available from Superintendent of Documents, U.S. Government PrintingOffice, Washington, DC 20402.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-29
17、59, United States.steel with a mild oxidant, such as a nitric acid solution, for thepurpose of the removal of free iron or other foreign matter, butwhich is generally not effective in removal of heat tint or oxidescale on stainless steel. In the case of stainless steels withadditions of sulfur for t
18、he purpose of improved machinability,passivation may also include the removal of sulfides from thesurface of the metal for the purpose of maximizing corrosionresistance.3.1.1.2 The formation of the protective passive film on astainless steel, also called passivation in a more generalcontext, will oc
19、cur spontaneously in air or other oxygen-containing environment when the stainless steel surface is freeof oxide scale and exogenous matter.3.1.1.3 Chemical treatments, such as sodium dichromatesolutions, may facilitate the more rapid formation of thepassive film on a stainless steel surface already
20、 free of scale orforeign matter. Such treatments, also sometimes called passi-vation in common usage, are designated as post-cleaningtreatments in this specification in order to distinguish themfrom chemical treatments capable of removing free iron fromstainless steels.3.1.1.4 The chemical treatment
21、s capable of removing heattint or oxide scale from stainless steel and capable of dissolvingthe stainless steel itself, typically called pickling, are substan-tially more aggressive than treatments used for passivation, asdefined in 3.1.1.1. The surface of stainless steel that has beenpickled is fre
22、e of scale, free iron, and exogenous foreignmatter, and does not require a separate treatment for passiva-tion as defined in 3.1.1.1. The passivation process defined in3.1.1.2 will occur without further chemical treatment but maybe augmented and improved by the post-cleaning treatmentsdefined in 3.1
23、.1.3.3.1.1.5 Electrochemical treatments, including electropick-ling and electropolishing capable of removing heat tint or oxidescale from stainless steel and capable of dissolving the stainlesssteel itself, are substantially more aggressive than treatmentsused for passivation, as defined in 3.1.1.1.
24、 The surface ofstainless steel resulting from these treatments is free of scale,free iron, and exogenous foreign matter, and does not require aseparate treatment for passivation as defined in 3.1.1.1. Thepassivation process defined in 3.1.1.2 will occur withoutfurther chemical treatment, but may be
25、augmented and im-proved by the post-cleaning treatments defined in 3.1.1.3.Statements regarding chemical treatments, unless otherwisespecified, are taken to include electrochemical treatments.4. Ordering Information4.1 It is the responsibility of the purchaser to specify a testpractice appropriate t
26、o any particular material and application.This specification was written for the purpose of providing analternative to United States Federal Specification QQ-P-35C.Determination of the suitability of this specification for thatpurpose is the responsibility of the purchaser.4.2 Unless specified by th
27、e purchaser, the chemical treat-ment applied to the stainless steel parts shall be selected by theseller from among the listed passivation treatments.5. Materials and Preparation for Passivation Treatments5.1 The passivation treatments shall be of one or more of thefollowing types. The effectiveness
28、 of a particular treatment fora particular grade of stainless steel in a particular application isdemonstrated by meeting the specified testing requirements:5.1.1 Treatments in nitric acid,5.1.2 Treatments in citric acid,5.1.3 Other chemical treatments, including electrochemicaltreatments,5.1.4 Neut
29、ralization, and5.1.5 Post-cleaning treatments.5.2 Materials:5.2.1 The chemicals used for passivation treatments shallproduce passivated surfaces that meet the requirements of oneor more of the tests of this specification. Attention shall begiven to maintaining adequate volume, concentration, purity,
30、and temperature control appropriate to the size and amount ofstainless steel to be treated.5.2.2 The processor shall maintain a record with regard toconcentration and temperature of the passivation solutionsufficient to demonstrate that the specified passivation condi-tions were maintained for each
31、lot of stainless steel partsprocessed. Such records shall be available for inspection whenspecified in the purchase order. The processor is not required toreveal the precise composition of proprietary chemical mix-tures but shall maintain a unique identification of the mixturethat will ensure its ac
32、curate representation for subsequent use.5.2.3 The processor shall be responsible for the safe dis-posal of all material generated by this process.5.3 Preparation for Passivation Treatments:5.3.1 The pretreatment methods and procedures used priorto the passivation treatment, including mechanical and
33、 chemi-cal methods, singly or in combination, for descaling andpickling, shall be in accordance with Practice A380. Whenelectrochemical cleaning is required, it shall be performed inaccordance with Practice B254.5.3.2 The resulting pretreated surface shall be substantiallyfree of oil, grease, rust,
34、scale, and other foreign matter.5.3.3 When the final pretreatment of a part includes picklingof the entire surface of the part, no further passivationtreatment is required prior to testing of the surface unlessspecified by the purchaser.6. Treatments in Nitric Acid Solutions6.1 Passivation Treatment
35、:6.1.1 Stainless steel parts shall be treated in one of thefollowing aqueous solutions and maintained within the speci-fied temperature range for the specified time.6.1.1.1 Nitric 1The solution shall contain 20 to 25 volumepercent of nitric acid and 2.5 6 0.5 weight percent of sodiumdichromate. The
36、parts shall be immersed for a minimum of 20min at a temperature in the range from 120 to 130F (49 to54C).6.1.1.2 Nitric 2The solution shall contain 20 to 45 volumepercent of nitric acid. The parts shall be immersed for aminimum of 30 min at a temperature in the range from 70 to90F (21 to 32C).A967 0
37、5226.1.1.3 Nitric 3The solution shall contain 20 to 25 volumepercent nitric acid. The parts shall be immersed for a minimumof 20 min at a temperature in the range from 120 to 140F (49to 60C).6.1.1.4 Nitric 4The solution shall contain 45 to 55 volumepercent of nitric acid. The parts shall be immersed
38、 for aminimum of 30 min at a temperature in the range from 120 to130F (49 to 54C).6.1.1.5 Nitric 5Other combinations of temperature, time,and concentration of nitric acid, with or without other chemi-cals, including accelerants, inhibitors, or proprietary solutions,capable of producing parts that pa
39、ss the specified test require-ments.6.2 Water RinseImmediately after removal from the pas-sivating solution the parts shall be thoroughly rinsed, usingstagnant, countercurrent, or spray washes singly or in combi-nation, with or without a separate chemical treatment forneutralization (see 9.1) of the
40、 passivation media, with a finalrinse being carried out using water with a maximum total solidscontent of 200 ppm.7. Treatments in Citric Acid7.1 Passivation Treatment:7.1.1 Stainless steel parts shall be treated in one of thefollowing aqueous solutions and maintained within the speci-fied temperatu
41、re range for the specified time.7.1.1.1 Citric 1The solution shall contain 4 to 10 weightpercent of citric acid. The parts shall be immersed for aminimum of 4 min at a temperature in the range from 140 to160F (60 to 71C).7.1.1.2 Citric 2The solution shall contain 4 to 10 weightpercent of citric acid
42、. The parts shall be immersed for aminimum of 10 min at a temperature in the range from 120 to140F (49 to 60C).7.1.1.3 Citric 3The solution shall contain 4 to 10 weightpercent of citric acid. The parts shall be immersed for aminimum of 20 min at a temperature in the range from 70 to120F (21 to 49C).
43、7.1.1.4 Citric 4Other combinations of temperature, time,and concentration of citric acid, with or without other chemi-cals to enhance cleaning, including accelerants, inhibitors, orproprietary solutions capable of producing parts that pass thespecified test requirements.7.1.1.5 Citric 5Other combina
44、tions of temperature, time,and concentrations of citric acid, with or without other chemi-cals to enhance cleaning, including accelerants, inhibitors, orproprietary solutions capable of producing parts that pass thespecified test requirements. Immersion bath to be controlled ata pH of 1.82.2.7.2 Wat
45、er RinseImmediately after removal from the pas-sivating solution, the parts shall be thoroughly rinsed, usingstagnant, countercurrent, or spray washes, singly or in combi-nation, with or without a separate chemical treatment forneutralization of the passivation media (see 9.2), with a finalrinse bei
46、ng carried out using water with a maximum total solidscontent of 200 ppm.8. Treatments in Other Chemical Solutions, IncludingElectrochemical Treatments8.1 It is recognized that the purpose of removal of allexogenous matter from a stainless steel surface, including theremoval of free iron, can be acc
47、omplished by different media,with potential for benefits to be gained from use of proprietaryskills and art, including proprietary passivation media. Suchtreatments may include externally applying an electrical po-tential on the stainless steel parts, as in the case of electropol-ishing. The suitabi
48、lity of such passivation treatments for use inmeeting the requirements of this specification shall be deter-mined by the capability of the processed parts meeting thespecified test requirements.8.2 Stainless steel parts shall be treated in a specifiedaqueous solution, with or without externally appl
49、ied electricalpotential, and maintained within a specified temperature rangefor a time sufficient for the processed parts to meet thespecified test requirement.8.3 Water RinseImmediately after removal from the pas-sivating solution, the parts shall be thoroughly rinsed, usingstagnant, countercurrent, or spray washes, singly or in combi-nation, with or without a separate chemical treatment forneutralization of the passivation media (see 9.2), with a finalrinse being carried out using water with a maximum total solidscontent of 200 ppm.9. Ne
