1、Designation: B600 11 (Reapproved 2017)Standard Guide forDescaling and Cleaning Titanium and Titanium AlloySurfaces1This standard is issued under the fixed designation B600; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f last revision. 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 U.S. Department of Defense.1. Scope1.1 This guide covers a cleaning a
3、nd descaling procedureuseful to producers, users, and fabricators of titanium andtitanium alloys for the removal of ordinary shop soils, oxides,and scales resulting from heat treatment operations and foreignsubstances present as surface contaminants.1.2 It is not intended that these procedures be ma
4、ndatory forremoval of any of the indicated soils but rather serve as a guidewhen titanium and titanium alloys are being processed in thewrought, cast, or fabricated form.1.3 It is the intent that these soils be removed prior tochemical milling, joining, plating, fabrication, and in anysituation wher
5、e foreign substances interfere with the corrosionresistance, stability, and quality of the finished product.1.4 Acid etching may be required following cleaning whenthe surface has an oxygen-contaminated layer or alpha casepresent.1.5 The values stated in inch-pound units are to be regardedas standar
6、d. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.6 This standard does not purport to address the safetyconcerns, if any, associated with its use. It is the responsibilityof the user of this standard to
7、consult and establish appropriatesafety and health practices and determine the applicability ofregulatory limitations prior to use.1.7 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for
8、 theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Processing Soil Removal2.1 It is recommended that grease, oil, and lubricantsemployed in machining, forming, and fabricating operations ontitan
9、ium and titanium alloys be removed by alkaline oremulsion soak-type cleaners and electrolytic alkaline cleaningsystems. In the electrolytic system the work may be eitheranodic or cathodic polarity. Removal of these soils is recom-mended prior to heat treatment or application of acid treatmentdesigna
10、ted in 4.2. When electrolytic systems are employed, thevoltage should be controlled to prevent the occurrence of sparkdischarge and subsequent pitting.3. Blast Cleaning3.1 Mechanical descaling methods such as sandblasting,shot blasting, and vapor blasting may be used to remove hotwork scales and lub
11、ricants from titanium surfaces if followedby thorough conditioning and cleaning as described in Section4.3.2 The sand used for blasting should be a high-grade,washed, iron-free, silica sand. If carbon or low-alloy steelproducts are sandblasted in the same facility, the sand used forcleaning these pr
12、oducts should not be used on titanium surfacesand a separate sand supply should be provided.3.3 Roughening of exposed surface areas may occur fromgrit or shot if cleaning of the entire surface is accomplished byblasting. Partial cleaning for preserving the surface finish is tobe preferred in conjunc
13、tion with proper pickling procedures.3.4 Blast cleaning that utilizes steel grit, steel shot, or sandcontaining appreciable amounts of iron should be followed byacid pickling to remove any embedded steel particles on thesurface of the titanium.3.5 Any abrasive or shot blast cleaning may induce resid
14、ualcompressive stresses in the surface of the material or titaniumstructure. Warpage may occur in sections that are subsequentlychemical milled or contour machined.3.6 In most cases, blast cleaning is not intended to eliminatepickling procedures completely. Abrasives will not removesurface layers co
15、ntaminated with interstitial elements such ascarbon, oxygen, and nitrogen. When these elements are present1This guide is under the jurisdiction of ASTM Committee B10 on Reactive andRefractory Metals and Alloys and is the direct responsibility of SubcommitteeB10.01 on Titanium.Current edition approve
16、d May 1, 2017. Published May 2017. Originallyapproved in 1974. Last previous edition approved in 2011 as B600 11. DOI:10.1520/B0600-11R17.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in acco
17、rdance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1in excessive amounts, they are
18、preferably removed by con-trolled acid pickling in accordance with 4.3.4. Pickling, Cleaning, and Descaling4.1 Recommended post treatment of shot or abrasive blastedtitanium surfaces may include acid pickling as described in4.3.2, or acid cleaning as described in 4.3.3. If the product is tobe chemic
19、al milled for the removal of the oxygen-contaminated layer, salt bath conditioning may be required toavoid selectively etched surfaces if configuration interfereswith uniform blasting.4.2 Scale and lubricant residues developed on mill, foundry,forged, or fabricated titanium products usually require
20、condi-tioning by one of the following commercial methods prior tofinal pickling as described in 4.3.2 to produce a completelyscale-free surface.4.2.1 Proprietary solutions of caustic-based compounds intap water in accordance with the manufacturers recommenda-tion.4.2.2 Molten alkaline-based salt bat
21、hs operating at 750 to850F (399 to 454C) in accordance with prescribed proce-dures.4.2.3 Molten alkaline-based salt baths operating at 400F(204C) in accordance with prescribed procedures.4.2.4 Oxides and heat tints developed below 1100F(593C) can frequently be removed by pickling in an acidsolution
22、composed of 10 to 20 volume % (150 to 300 g/L) ofnitric acid (70 %) and 1 to 2 volume % (12 to 24 g/L) ofhydrofluoric acid (60 %) at 120F (49C).4.2.5 Forged and hot-worked titanium alloys that have thenormal heat-developed scale mixed with graphitic or glass-typelubricants may be conditioned in a mo
23、lten alkaline-based saltbath operating at 850F (454C) to effect complete solubility ofthe complex scale. Following conditioning, the part should bepickled as described in 4.3.2.4.2.6 It is recommended that heat-treatable alpha beta andbeta alloys in the solution-treated condition that have beenproce
24、ssed at temperatures above 1100F (593C), with gra-phitic and molybdenum disulfide lubricant residues mixed withthe heat-developed scale, be conditioned in a molten alkaline-based salt bath operating at 400F (204C). After conditioning,the part may be pickled in accordance with the treatmentdescribed
25、in 4.3.2.4.2.7 Abrasive methods such as wheel or belt grinding,segmented flapper wheels, and grit or shot blasting, whenavailable, may be used when surface configuration is such thatthe scaled areas are readily accessible.NOTE 1Conditioning of titanium in high-temperature oxidizing saltcan generate
26、galvanic currents where the work is contacting ferrous basematerials. Titanium is electrically positive or anodic with respect to theseferrous materials, having an open circuit potential of approximately 0.60V. The resulting discharge from the rack to the work piece can result insurface over-heating
27、 and eventual ignition. This effect can be minimizedby maintaining bath temperature at or below 850F (455C) and byproviding titanium fixtures or aluminum insulation between the work andthe fixture.NOTE 2Heavily scaled forgings or hot-rolled materials can bemechanically abraded to remove excess surfa
28、ce contamination prior to saltbath conditioning.NOTE 3Silicon-based protective coatings used to minimize scaleformation during hot forming or annealing of titanium alloys are solublein the molten salt bath. All of the coating should be removed prior to anyacid treatment.4.3 Following mechanical abra
29、ding or chemicalconditioning, the material may be further treated to completelyclean the surface in one of the following solutions:4.3.1 After salt bath conditioning and water rinse, thetitanium or titanium alloy may be immersed in a sulfuric acidsolution to remove the converted scale product. It is
30、 recom-mended that the acid solution be maintained at 150F (66C)and a concentration of 10 to 40 volume % of sulfuric acid(95 % solution by weight). Final brightening may be accom-plished by a short immersion in the acid solution of 4.3.2.4.3.2 To ensure complete removal of metallic iron, oxide,scale
31、, and other surface contaminants, material that has beenmechanically abraded in accordance with 3.1 or chemicallyconditioned in accordance with 4.2.1, 4.2.2,or4.2.3 may befinish cleaned by immersion in an acid solution composed of10 to 30 volume % (150 to 450 g/L) of nitric acid (70 %) and1 to 3 vol
32、ume % (12 to 36 g/L) of hydrofluoric acid (60 %) at120F (49C), maintaining a ratio of 10 parts nitric acid to 1part hydrofluoric acid.NOTE 4Hot-formed or heat-treated titanium fabrications or assem-blies that have a mixed surface contamination consisting of graphite ormolybdenum disulfide with titan
33、ium oxides should be conditioned in amolten salt bath. The 400F (204C) temperature is preferred for thesestructures to avoid any thermally induced distortion.NOTE 5In salt bath or alkaline water solution conditioning, thetitanium oxides present on the surface of the metal are chemically reactedto fo
34、rm sodium titanate. This material is soluble in the sulfuric andnitric-hydrofluoric acid pickles. The sulfuric acid solutions are notappreciably corrosive to titanium or titanium alloys and can be furtherinhibited by the addition of 0.25 to 1.0 % of cupric sulfate or ferroussulfate.NOTE 6Most of the
35、 acid pickling following molten salt bath condi-tioning is accomplished in the sulfuric or nitric-hydrofluoric acid solution.The material is cycled through the salt bath, water rinse, and sulfuric aciduntil all of the scale has been completely removed. Final brightening isobtained by a brief cycle i
36、n the nitric-hydrofluoric solution (4.3.2).NOTE 7In the nitric-hydrofluoric pickling solution, the ratio of nitricacid to hydrofluoric acid is more important than the concentration of eitherof these two acids. When this ratio is maintained at 10 to 1, hydrogenabsorption during pickling is minimized.
37、NOTE 8In the processing of titanium mill products and fabrications,an oxygen-rich layer is unavoidable where there is a combined exposureto high temperatures and an oxidizing atmosphere. In the removal of thisoxygen-rich layer or alpha case by pickling in strong solutions of nitricand hydrofluoric a
38、cids, it is extremely important that all residual oxide andscale has been removed to prevent preferential etching of the finishedproduct.NOTE 9Hydrogen in excess of the specified amount may be removedby vacuum annealing of the cleaned work piece.NOTE 10Hydrofluoric acid at 48 % concentration can be
39、used in placeof the 60 % concentration. If this is done, the ratio of nitric to hydrofluoricshould be 8 to 1.NOTE 11Turning, peeling, and centerless grinding have also beensuccessfully utilized as alternative descaling and cleaning methods forround bar.4.3.3 To ensure complete removal of metallic ir
40、on and othersurface contaminants, material that has been mechanicallyabraded in accordance with 3.1 or chemically conditioned inaccordance with 4.2.1, 4.2.2,or4.2.3 may be finish cleaned byB600 11 (2017)2immersion in one of the following acid solutions and main-tained within the specified temperatur
41、e range for the specifiedtime.4.3.3.1 The solution should contain 20 to 25 volume percentof nitric acid. The parts should be immersed for a minimum of20 min at a temperature in the range from 120 to 140F (49 to60C) or 30 min at a temperature in the range from 70 to 90F(21 to 32C).4.3.3.2 The solutio
42、n should contain 4 to 10 weight percentof citric acid. The parts should be immersed for a minimum of4 min at a temperature in the range from 140 to 160F (60 to71C), a minimum of 10 min at a temperature in the range from120 to 140F (49 to 60C), or a minimum of 20 min at atemperature in the range from
43、 70 to 120F (21 to 49C).NOTE 12Acid cleaning (4.3.3) is not intended to remove residualoxide and scale.5. Inspection5.1 Visual inspection of material cleaned in accordance withthis guide should show no evidence of paint, oil, grease, glass,graphite lubricant, scale, abrasive, iron, or other forms of
44、contamination.5.2 Hydrogen absorption during the cleaning process shouldbe minimized and well within tolerable limits if the proceduresoutlined are followed. Periodic monitoring of the cleaningsystem can be accomplished by processing samples of knownhydrogen content through the complete system follo
45、wed bychemical analyses. A hydrogen increase greater than 20 ppmover the original product analyses may be cause for replacingthe acids or adjusting the composition to reduce the extent ofhydrogen pickup.5.3 Additional evaluation of product cleanliness may beobtained by chemical milling of an expenda
46、ble sample testpiece. It is recommended that approximately 0.001 to 0.002 in.(0.025 to 0.05 mm) should be removed from each surface.After chemical milling, the surface should be uniformlysmooth and bright with the absence of peaks indicative ofresidual scale or contamination.6. Keywords6.1 alpha cas
47、e; cleaning; descaling; pickling; titanium; tita-nium alloyASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such pat
48、ent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited eit
49、her for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individ
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