1、Designation: F326 96 (Reapproved 2012)Standard Test Method forElectronic Measurement for Hydrogen Embrittlement FromCadmium-Electroplating Processes1This standard is issued under the fixed designation F326; the number immediately following the designation indicates the year of originaladoption or, i
2、n the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscriptepsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers an electronic hydrogen detec-tion instrument procedure for mea
3、surement of plating perme-ability to hydrogen. This method measures a variable related tohydrogen absorbed by steel during plating and to the hydrogenpermeability of the plate during post plate baking. A specificapplication of this method is controlling cadmium-platingprocesses in which the plate po
4、rosity relative to hydrogen iscritical, such as cadmium on high-strength steel.1.2 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 dete
5、rmine the applica-bility of regulatory limitations prior to use. For specific hazardstatement, see Section 8.1.3 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for
6、 Reagent WaterF519 Test Method for Mechanical Hydrogen EmbrittlementEvaluation of Plating/Coating Processes and Service En-vironments3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 hydrogen pressure peakthe maximum hydrogenpressure value (see IH) obtained when the probe is hea
7、tedfollowing calibration, plating, or fluid testing.3.2 Symbols:3.2.1 HP = calibration hydrogen pressure peak.3.2.2 HPp= plating hydrogen pressure peak.3.2.3 IE= probe cathode emission current.3.2.4 IH= probe hydrogen pressure.3.2.5 I= integral of IHcurve from probe on to HP.3.2.6 lambda = time in s
8、econds for hydrogen pressure peakto drop to half its value.3.2.7 = lambda obtained from a calibration run.3.2.8 p= lambda obtained from a plating run.3.2.9 pc= normalized test lambda, obtained as follows:pc5 p40/! (1)3.2.10 pc= arithmetic average of normalized lambdas for aset of tests.3.2.11 range
9、= difference between maximum pcand mini-mum pcfor a given set of tests.3.2.12 run = calibration or plating of a probe.3.2.13 test = single evaluation of a plating solution forhydrogen embrittlement determination; run using a previouslycalibrated probe.3.2.14 set of testsall consecutive tests on a pl
10、ating solu-tion for a given operator-instrument-day evaluation.3.2.15 windowtest surface of a probe described in Fig.1(A).4. Summary of Test Method4.1 This method uses a metal-shelled vacuum probe as anion gage to evaluate electrodeposited cadmium characteristicsrelative to hydrogen permeation. Afte
11、r calibration, a section ofthe probe shell is electroplated at the lowest current densityencountered in the cadmium electroplating process. During thesubsequent baking of the probe at a closely controlledtemperature, the probe ion current, proportional to hydrogenpressure, is recorded as a function
12、of time. From these data andthe calibration data of the probe, a number related to theporosity of the electroplated metal relative to hydrogen isobtained.4.2 During the initial part of the bakeout, hydrogen contin-ues to diffuse through the metal shell of the probe and the ion1This test method is un
13、der the jurisdiction of ASTM Committee F07 onAerospace and Aircraft and is the direct responsibility of Subcommitteee F07.04 onHydrogen Embrittlement.Current edition approved Nov. 1, 2012. Published November 2012. Originallyapproved in 1978. Last previous edition approved in 2006 as F326 96 (2006).D
14、OI: 10.1520/F0326-96R12.2For 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 Document Summary page onthe ASTM website.Copyright ASTM International, 100 Bar
15、r Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1current increases. Within a short time, however, a maximumcurrent is observed and then falls off as hydrogen is driven outof the system.4.3 Observations of the ion current-time curve indicate thatthe slope of the curve has
16、an empirical relationship with failuredata on stress rupture specimens such as those in Test MethodF519. For this method, Iand variables (see Section 3) mustbe empirically correlated with results from the stress rupturespecimens. This gives a quick means of measuring ease ofbaking hydrogen out of ca
17、dmium-electroplated parts.4.4 Before an electroplating test, calibration is accom-plished by electrolyzing the probe in a standard solution andbaking it to determine Iand of the unplated steel shell of theprobe.5. Significance and Use5.1 Hydrogen is evolved during metal electrodeposition inaqueous b
18、aths. Some of this hydrogen enters parts duringplating. If the absorbed hydrogen is at a level presentingembrittlement hazards to high-strength steel, it is removed bybaking parts after plating to expel this hydrogen. However, thelack of plate porosity itself may block hydrogen egress. Thus,it becom
19、es important to know both the relative amount ofhydrogen absorbed and the plate porosity.5.2 This test provides a quantitative control number forcadmium plate porosity that can be used to control a cadmiumplating process and the status of cadmium-plated hardware. Itcan also be used for plating proce
20、ss troubleshooting andresearch and development to determine the effects on plateporosity by process variables, contaminants, and materials.When used to control a critical process, control numbers forplate porosity must be determined by correlation with stressrupture specimens or other acceptable sta
21、ndards.5.3 There is no prime standard for plate porosity. For thisreason, two ovens must be used, with tests alternated betweenovens. Data from the ovens are compared to ensure noequipment change has occurred.6. Apparatus6.1 Hydrogen Detection InstrumentAsystem consisting ofa control unit, two speci
22、al ovens, auxiliary heater, recorder, testprobes, and associated equipment.6.2 OvenThe oven warms the probe to increase thehydrogen diffusion rate into the probe. Oven parameters areselected by apparatus manufacturer to provide a standardreading for all hydrogen detection instruments.6.3 Oven Stoppe
23、rStopper covering the oven opening.Remove 10 s before inserting the probe.6.4 WindowThe window is the unpainted, bare steelportion of the probe, 0.63 6 0.03 in. in height, that is plated inthe solution under test. The window is shown in Fig. 1.6.5 Abrasive BlastAbrasive blast window area in the same
24、way, using the same media, as used for the parts. Probe shouldbe rotated while being blasted to provide uniform surface.6.6 Electronic Bakeout UnitThis heats the probe electri-cally to remove hydrogen absorbed into the probe after testing.May be part of hydrogen detection instrument.7. Reagents and
25、Materials7.1 Reagents:7.1.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.3O
26、ther grades may be used,provided it is first ascertained that the reagent is of sufficienthigh purity to permit its use without lessening the accuracy ofthe determination.7.1.2 Acetone (C3H6O), technical.7.1.3 Anode Cleaning SolutionConcentrated nitric acid(HNO3), reagent grade.7.1.4 Cadmium Strippi
27、ng SolutionAmmonium Nitrate(125 g/L)Dissolve 125 g of ammonium nitrate (NH4NO3,technical) in water and dilute to 1 L. Use at room temperature.7.1.5 Calibration SolutionSodium Cyanide (50 g/L) PlusSodium Hydroxide (50 g/L)Dissolve 50 g of sodium hydrox-ide (NaOH) in water.Add 50 g of sodium cyanide (
28、NaCN) anddissolve. Dilute to 1 L. Use at 18 to 27C (65 to 80F).3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals,
29、BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.FIG. 1 Probe ConfigurationF326 96 (2012)27.1.6 Water, Distilled or Deionized, minimum electricalresistivity 50 000 cm (for example, Specification D1193).7
30、.2 Materials:7.2.1 Anodes (Calibration), solid-carbon arc rods, 5.1- to12.7-mm (0.20- to 0.50-in.) diameter.7.2.2 Anodes (Plating), cadmium rods, A-A-51126 6.4 to12.7 mm (0.25 to 0.50 in.) thick, round or square.7.2.3 Polytetrafluoroethylene (PTFE) TapeThe tapeshould be appropriate for use in soluti
31、on, width about 12 to 19mm, thickness small enough to seal.7.2.4 Glass 1-L Beaker.8. Hazards8.1 Sodium cyanide, cyanide, cadmium, nitric acid, andacetone can be health hazards. Use adequate face, hands, andrespiratory protection commensurate with standards estab-lished by American Conference of Gove
32、rnment and IndustrialHygiene for these chemicals.9. Sampling9.1 Stir plating bath to ensure homogeneity. The platingbath sample must be representative of the bath. Obtain thesample from beneath the surface of the bath, not by skimmingthe surface. Chemical constituents must be within normaloperating
33、range.10. Preparation of Apparatus10.1 Plug in instrument and allow sufficient time for war-mup.10.2 Turn on the oven and allow 4 h for warmup.10.3 Leave the instrument on continuously.10.4 Clean contaminated anodes in cleaning solution,(7.1.3) until heavy gassing is observed. (WarningSee Sec-tion 8
34、.)11. Calibration of Apparatus11.1 Calibration Position, 1.08 6 0.2 A/dm2(10 6 2A/ft2)Use nominal dimensions of Fig. 1(A) for currentcalculations.11.2 Plating Position, 62 % of CurrentSet plating currentdensity at the minimum value allowed by the plating specifi-cation.11.3 Probe Current, Ie, 6 6 0.
35、2 mA.11.4 Electronic Probe Bakeout, 100 6 10 mA.11.5 Probe IH: 1 IHunit = 107ALinearity, 62 % full scale within eachrange, 1 to 10 00011.6 OvensOvens are calibrated by the manufacturersagainst standard ovens that in turn were calibrated withnotched tension specimen data. Oven stability is checked by
36、comparing ovens against each other in duplicate tests.11.7 Correlation of OvensTo correlate ovens, determinepcfor all tests of a set (except tests discarded in accordancewith 13.4.4). From pcand the number of tests, determine from Fig. 2. Separate data and compute pcfor each oven. Letpc(A) be the hi
37、gher value and pc(B) the lower value. Wherepc(A)pc(B) is less than , the ovens are comparable.Where pc(A) pc(B) is greater than , the ovens are notcomparable.12. Procedure12.1 Bakeout of Probe:12.1.1 Strip cadmium-plated probes in stripping solution(7.1.4) and rinse in 50C (122F) water for 2 min bef
38、orebakeout.12.1.2 Insert a probe into the socket of an electronic bakeoutunit.12.1.3 Within 30 s, the heater should stabilize or be adjustedto 86.5 6 16.5 mA. If the heater does not register current, theprobe is defective and must be discarded.12.1.4 Bake out the probe for the time required to meet
39、thelimits in 12.2. Do not continuously bake out probes for longerthan2htopreclude damaging paint.12.2 Probe CheckoutProbes that are new, or have beencalibrated or plated and stripped, need to be baked out to meetcheckout requirements as follows:12.2.1 Hot Probe:12.2.1.1 Set the range to 10.NOTE 1Her
40、e and throughout the specification, range settings are forfull-scale reading.12.2.1.2 Remove the probe from the electronic bakeout unit;plug into the socket assembly and 15 6 1 s after removal fromthe bakeout unit, turn the probe on.12.2.1.3 Observe the peak value of IH. If less than 1,proceed with
41、surface activation. If it is greater than 1.0, screwon the cap and insert probe into the oven.12.2.1.4 If IHis 0.5 or less within 5 min of inserting theprobe into the oven, proceed to surface preparation. If theprobe does not drop to IH= 0.5 or less with 5 min, bake outagain. If three successive bak
42、eouts do not reduce IHto 0.5 orless within 5 min of insertion into the oven, discard the probe.12.2.1.5 Set the instrument to read IE. Probe IEshould read6.0 6 0.2 mA. If IEdoes not read or cannot be adjusted to this,the probe or the instrument is defective. Check the instrumentwith other probes to
43、determine which is defective. Discarddefective probes.12.2.2 Cold Probe:12.2.2.1 Set the range to 1.0.12.2.2.2 Plug the probe into socket assembly and turn on.12.2.2.3 Observe the peak value of IH. If less than 0.2,proceed to surface preparation. If greater than 0.2, insert intothe oven.12.2.2.4 Pro
44、ceed as in 12.2.1, 12.2.1.4, and 12.2.1.5.12.3 Surface PreparationBefore the probe windowpreparation, check to ensure the window width and heightabove the probe base meet the requirements of Fig. 1(A). Theprobes having windows out of limits must be cleaned andrepainted in accordance with the supplie
45、rs instructions ordiscarded.12.3.1 Mask the probe to meet the requirement of Fig. 1(B)using conforming masks, supplied with instruments or PTFEadhesive tape. Edges of masks must coincide with edges ofF326 96 (2012)3window with no paint being visible. Protect the base of theprobe. Remove abrasive dus
46、t from the rubber masks to avoidpaint damage.12.3.2 For processes using current densities under 4.32A/dm2(40A/ft2), use production equipment to blast productionparts. For processes with higher current densities, use labora-tory blast equipment. Dry abrasive blast the window area of theprobe. Use mat
47、erial, size, air pressures, and distances repre-sentative of production blasting. Dry abrasive blast beforecalibration may be in a laboratory cabinet.NOTE 2Some production facilities may not be adaptable to blasting ofprobes. Special procedures will need to be approved by the procuringagency.12.3.3
48、Remove conformal blasting masks, ensuring that thewindow area is not touched. Remove loose abrasive byblowing off with filtered compressed air or by using a tissuepaper, taking care not to scratch the paint. Fingerprints orvisible contamination on the window invalidate the run.12.3.4 Visually inspec
49、t the window area for cleanliness anduniformly textured surface representative of production parts.Repeat Steps 12.3.1-12.3.3 as required to provide acceptablecleanliness and texture.12.3.5 Proceed to the calibration run or plating run asapplicable; immerse the probe within 10 min after sandblast-ing.12.4 Probe Calibration:12.4.1 Pour 850 6 50 mL (28.6 6 0.17 fl oz) of calibrationsolution (7.1.5) into a clean, dry 1-L beaker and insert fourcarbon anodes, (7.2.1) equally spaced and rigidly mounted tofit snug
