1、Designation: B 614 05Standard Practice forDescaling and Cleaning Zirconium and Zirconium AlloySurfaces1This standard is issued under the fixed designation B 614; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revi
2、sion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 a
3、lloys 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 zirc
4、onium 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, fabrication, and in anysituation where foreign substances interfere with the corrosionresistance, stability, and quality
5、 of the finished product.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 independen
6、tly of the other. SI valuescannot be mixed with inch-pound values. The temperatures inNotes 1 and 2 are exact equivalents because they reflect dataobtained from a specific temperature.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is ther
7、esponsibility of the user of this standard to establish appro-priate safety and health practices and determine the 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 machinin
8、g,forming, and fabricating operations on zirconium and zirco-nium alloys should be removed by employing one of themethods 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 immersionwashin
9、g or vapor degreasing, or (4) electrolytic alkalinecleaning system. In the electrolytic system, the work can beeither 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
10、treatment designated in Section 4. When electrolyticsystems are employed, the voltage should be controlled toprevent 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 recommen
11、ded solvent in this standard. Care must be exer-cised when using chemical solvents. There are hazards associ-ated 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 blasti
12、ng may be used to remove hotwork scales and lubricants from zirconium surfaces if followedby thorough conditioning 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
13、used media may be requiredto avoid excessive working of the metal surface by dullparticulate.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 conjun
14、ction with proper pickling procedures.3.4 Any abrasive or shot blast cleaning may induce residualcompressive stresses 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
15、intended to eliminatepickling procedures completely. However, there are caseswhere blast cleaning does not need to 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 SubcommitteeB10.0
16、2 on Zirconium and Hafnium.Current edition approved May 1, 2005. Published June 2005. Originallyapproved in 1977. Last previous edition approved in 2000 as B 614 95 (2000).1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.operation. Ab
17、rasives may not remove surface layers contami-nated with interstitial elements such as carbon, oxygen, 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 Recommende
18、d post treatment of shot or abrasive blastedzirconium surfaces may include acid pickling as described in4.3 to ensure complete removal of metallic iron, oxide, scale,and other surface contaminants.4.2 Scale and lubricant residues developed on mill, foundry,forged, or fabricated zirconium products us
19、ually 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 manufacturersrecommendation.4.2.2 Molten a
20、lkaline-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 an acidsolution composed of 25 to 50 volume % (350 to 700 g/L) ofnitric acid (70 %) and 3 to 7 v
21、olume % (36 to 84 g/L) ofhydrofluoric acid (60 %) at 120F (50C); balance tap water.4.2.4 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 su
22、ch that the scaled areasare readily accessible.NOTE 1Weight losses per unit time of zirconium and zirconium alloyspickled in a constant-temperature standard nitric-hydrofluoric acid solu-tion are dependent on the concentration of hydrofluoric acid maintained.For a pickling time of 7 min in a 100F (3
23、8C), 80 % (1120 g/L) nitric acidpickle, weight losses of 1, 2, 3, 4, and 5 g/dm2have been observed withrespective concentrations of 1, 2, 3, 4, and 5 % (12 to 60 g/L) hydrofluoricacid. With a 30 % (420 g/L) nitric acid concentration, the equivalentweight loss figures lie in the range of 1.75, 2.75,
24、3.75, 4.75, and 6.4 g/dm2. Acid concentrations represent 70 weight % nitric acid and 49 weight %hydrofluoric acid.NOTE 2Weight losses per unit time of zirconium and zirconium alloyspickled in standard nitric-hydrofluoric pickling solutions are highlytemperature-dependent. For a pickling time of 7 mi
25、n in a 39 volume %(5469 g/L) and 3.5 volume % (42 g/L) hydrofluoric acid, weight losseswere 5, 8, and 11 g/dm2at temperatures of 110F (43C), 140F (60C),and 160F (71C), respectively.4.3 Following mechanical abrading or chemical condition-ing, the material may be further treated to clean the surfaceco
26、mpletely using the following solution:4.3.1 Material that has been mechanically abraded in accor-dance with 3.1, or 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
27、3 to 7 volume % (36 to 84 g/L) ofhydrofluoric acid (60 %) at 120F (50C) maintaining a ratio of10 parts nitric acid to 1 part hydrofluoric acid.NOTE 3Most of the acid pickling following molten salt bath condi-tioning is accomplished in the sulfuric or nitric-hydrofluoric acid solution.The material is
28、 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.NOTE 4In the nitric-hydrofluoric pickling solution, the ratio of nitricacid to hydrofluori
29、c 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.NOTE 5The components should be rinsed immediately and thor-oughly in cold tap water following pickling to avoid staining of thesurfac
30、es with residual fluorides or chlorides which may be detrimental insome services.NOTE 6In 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-ri
31、ch layer by pickling in strong solutions of nitric and 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
32、 show no evidence of paint, oil, grease,glass, graphite, 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 cleanin
33、gsystem can be accomplished by processing samples of 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 ofhyd
34、rogen pickup.5.3 Additional evaluation of product cleanliness 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 smo
35、oth andbright with the absence of peaks indicative of 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. Bef
36、ore using any of these materials consulta standard reference 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 t
37、o dispose of suchdust by burning in small (approximately 1-lb (0.5-kg) quan-tities.NOTE 7Burning of Zr fines may not be permitted in all jurisdictions.7. Keywords7.1 cleaning; descaling; zirconium; zirconium alloysB614052ASTM International takes no position respecting the validity of any patent righ
38、ts asserted in connection with any item mentionedin this standard. 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
39、time by the responsible technical committee and must be reviewed 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 wil
40、l 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 AST
41、M International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, 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).B614053
