1、Designation: B614 10Standard Practice forDescaling and Cleaning Zirconium and Zirconium AlloySurfaces1This standard is issued under the fixed designation B614; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revisi
2、on. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers a cleaning and descaling procedureuseful to producers, users, and fabricators of zirconium andzirconium allo
3、ys 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 become manda-tory for removal of any of the indicated soils but rather serveas a guide when zirconi
4、um and zirconium alloys are beingprocessed in the wrought, cast, or fabricated form.1.3 It is the intent that these soils be removed prior tochemical milling, joining, plating, welding, fabrication, and inany situation where foreign substances interfere with thecorrosion resistance, stability, and q
5、uality of the finishedproduct.1.4 Unless a single unit is used, for example, solutionconcentrations in g/l, the values stated in either inch-pound orSI units are to be regarded separately as standard. The valuesstated in each system are not exact equivalents; therefore, eachsystem must be used indep
6、endently of the other. SI valuescannot be mixed with inch-pound values.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine th
7、e applica-bility of regulatory limitations prior to use. For specific hazardstatements, see Sections 2 and 6.2. Processing Soil Removal2.1 Grease, oil, and lubricants employed in machining,forming, and fabricating operations on zirconium and zirco-nium alloys should be removed by employing one of th
8、emethods or a combination of methods as listed: (1) alkaline oremulsion soak-type cleaners, (2) ultrasonic cleaning, (3) ac-etone, citrus based cleaners, or safety solvent immersionwashing or vapor degreasing, or (4) electrolytic alkalinecleaning system. In the electrolytic system, the work can beei
9、ther anodic or cathodic polarity provided voltage and currentdensity are controlled to avoid anodizing. Removal of thesesoils is recommended prior to heat treatment or application ofacid treatment designated in Section 4. When electrolyticsystems are employed, the voltage should be controlled toprev
10、ent the occurrence of spark discharge and subsequentpitting. The use of trichloroethylene is not prohibited and canbe used; however its use is hazardous enough to preclude it asa recommended solvent in this standard. Care must be exer-cised when using chemical solvents. There are hazards associ-ated
11、 with their use, such as flammability, carcinogenicity, andozone depletion (see 6.1.)3. Blast Cleaning3.1 Mechanical descaling methods such as sandblasting,shot blasting, and vapor blasting may be used to remove hotwork scales and lubricants from zirconium surfaces if followedby thorough conditionin
12、g and cleaning as described in Section4.3.2 Aluminum oxide, silicon carbide, silica sand, zirconsand, and steel grit are acceptable media for mechanicaldescaling. Periodic replacement of used media may be requiredto avoid excessive working of the metal surface by dullparticulate.3.3 Roughening of ex
13、posed 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 conjunction with proper pickling procedures.3.4 Any abrasive or shot blast cleaning may induce residualcompressive stre
14、sses in the surface of the material or zirconiumstructure. Warpage may occur in sections that are subsequentlychemical milled or contour machined.3.5 In most cases, blast cleaning is not intended to eliminatepickling procedures completely. However, there are caseswhere blast cleaning does not need t
15、o be followed by a pickling1This practice is under the jurisdiction of ASTM Committee B10 on Reactiveand Refractory Metals and Alloys and is the direct responsibility of SubcommitteeB10.02 on Zirconium and Hafnium.Current edition approved May 1, 2010. Published May 2010. Originallyapproved in 1977.
16、Last previous edition approved in 2005 as B614 05. DOI:10.1520/B0614-10.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.operation. Abrasives may not remove surface layers contami-nated with interstitial elements such as carbon, oxyge
17、n, hydro-gen, and nitrogen. When these elements are present in exces-sive amounts, they are preferably removed by controlled acidpickling in accordance with 4.3.4. Pickling and Descaling4.1 Recommended post treatment of shot or abrasive blastedzirconium surfaces may include acid pickling as describe
18、d in4.3 to ensure complete removal of metallic iron, oxide, scale,and other surface contaminants. Note that pickling does notneed to be the final surface conditioning. Mechanical methodsmay be acceptable as final conditioning steps.4.2 Scale and lubricant residues developed on mill, foundry,forged,
19、or fabricated zirconium products usually require con-ditioning by one of the following commercial methods prior tofinal pickling as described in 4.3 to produce a completelyscale-free surface.4.2.1 Proprietary solutions of caustic- or organic-basedcompounds in tap water in accordance with the manufac
20、turersrecommendation.4.2.2 Molten alkaline-based salt baths operating at 1200 to1300F (650 to 700C) in accordance with prescribed proce-dures.4.2.3 Oxides and heat tints developed below 1000F(540C) can frequently be removed by pickling in a nitric acid hydrofluoric acid solution. Common input acid s
21、trengthsused are 70 % by weight for HNO3acid and 48 % by weightfor HF acid. HF acid at 60 % strength has been used in the pastbut there are additional transportation restrictions on thishigher strength acid.4.2.4 The pickling acid solution is composed of 25 to 50 %by volume of 70 % strength HNO3acid
22、 and 3.8 to 8.8 % byvolume of 48 % strength HF acid. The balance is clean filteredwater. This yields a solution having 350 to 700 mg/L of nitricacid and 36 to 84 mg/L of hydrofluoric acid. Pickling should bedone in a solution with a temperature less than 120F (50C)and preferably nearer to 90F (30C).
23、4.2.5 Abrasive methods such as wheel or belt grinding,high-speed tool steel or carbide grinding, or both, segmentedflapper wheels, and grit or shot blasting, when available, maybe used when surface configuration is such that the scaled areasare readily accessible.NOTE 1The pickling rate (weight loss
24、 per unit time mg/dm2perminute) of zirconium and zirconium alloys is dependent on acid concen-trations and temperature. The following table and Fig. 1 show theserelationships.Vol%HNO3Vol%HFTemp WT Loss80 1.0 100 1.0080 2.0 100 2.0080 3.0 100 3.0080 4.0 100 4.0080 5.0 100 5.0030 1.0 100 1.7530 2.0 10
25、0 2.7530 3.0 100 3.7530 4.0 100 4.7530 5.0 100 6.4039 3.5 110 5.0039 3.5 140 8.0039 3.5 160 11.004.2.5.1 For example, the use of 30 % HNO3with HF at100F increases the pickle rate compared to the use of an 80 %HNO3solution with the same HF concentration. Also, anincrease in temperature from 110 to 16
26、0F more than doublesthe pickle rate (5.0 to 11.0 mg/dm2in 7 min.).4.3 Following mechanical abrading or chemical condition-ing, the material may be further treated to clean the surfacecompletely using the following solution:4.3.1 Material that has been mechanically abraded in accor-dance with 3.1, or
27、 chemically conditioned in accordance with4.2.1 and 4.2.2, may be finish-cleaned by immersion in an acidsolution composed of 25 to 50 volume % (350 to 700 g/L) ofnitric acid (70 %) and 3 to 7 volume % (36 to 84 g/L) ofhydrofluoric acid (60 %) at 120F (50C) maintaining a ratio of10 parts nitric acid
28、to 1 part hydrofluoric acid. HydrofluoricFIG. 1 WT Loss vs HF, HNO3and TemperatureB614 102acid at 48 % concentration can be used in place of the 60 %concentration. If this is done, the ratio of nitric to hydrofluoricshould be 8 to 1.NOTE 2Most of the acid pickling following molten salt bath condi-ti
29、oning is accomplished in the sulfuric or nitric-hydrofluoric acid solution.The material is cycled through the salt bath, water rinse, and acid until allof the scale has been completely removed. Final brightening is obtainedby a brief cycle in the nitric-hydrofluoric solution, in accordance with 4.3.
30、NOTE 3In 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. Hydrofluoric acid at 48 %concentration can
31、 be used in place of the 60 % concentration. If this isdone, the ratio of nitric to hydrofluoric should be 8 to 1.NOTE 4The components should be rinsed immediately and thor-oughly in cold tap water following pickling to avoid staining of thesurfaces with residual fluorides or chlorides which may be
32、detrimental insome services.NOTE 5In the processing of zirconium 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 by pickling in strong solutions of nitric an
33、d hydrofluoricacids, it is extremely important that all residual oxide and scale have beenremoved to prevent preferential etching of the finished product.5. Inspection5.1 Visual inspection of material cleaned in accordance withthis practice should show no evidence of paint, oil, grease,glass, graphi
34、te, lubricant, scale, abrasive, iron, or other formsof 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
35、knownhydrogen content through the complete system followed bychemical analyses.Ahydrogen increase greater than 2 to 5 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 cle
36、anliness may beobtained by chemical milling of an expendable sample testpiece. It is recommended that approximately 0.001 to 0.002 in.(0.025 to 0.05 mm) shall be removed from each surface. Afterchemical milling, the surface should be uniformly smooth andbright with the absence of peaks indicative of
37、 residual scale orcontamination.6. Hazards6.1 Cleaning using this practice involves the use of hazard-ous chemicals. These chemicals are as follows: acetone, nitricacid, hydrofluoric acid, molten cleaning salts, and alkalinecleaning solutions. Before using any of these materials consulta standard re
38、ference on safe use of chemicals or the manufac-turers recommendations for safe handling.6.2 Grinding and grit blasting of zirconium can create a finemetal dust that is flammable and dangerous if allowed toaccumulate. Precautions should be taken to dispose of suchdust by burning in small (approximat
39、ely 1-lb (0.5-kg) quan-tities.NOTE 6Burning of Zr fines may not be permitted in all jurisdictions.7. Keywords7.1 cleaning; descaling; zirconium; zirconium alloysASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this sta
40、ndard. Users of this standard are expressly advised that determination of the validity of any such patent 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 revi
41、ewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either 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 theresponsib
42、le 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 Co
43、nshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).B614 103
