1、Designation: F326 96 (Reapproved 2012)F326 17Standard 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 originaladoptio
2、n or, in 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 detection instrument procedure f
3、or measurement of plating permeability tohydrogen. This method measures a variable related to hydrogen absorbed by steel during plating and to the hydrogen permeabilityof the plate during post plate baking. A specific application of this method is controlling cadmium-plating processes in which thepl
4、ate porosity relative to hydrogen is critical, such as cadmium on high-strength steel.1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.1.3 This standard does not purport to address all of the safety concerns, if any, assoc
5、iated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use. For specific hazard statement, see Section 8.1.3 The values stated in SI u
6、nits are to be regarded as the standard. The values given in parentheses are for information only.1.4 This international standard was developed in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International St
7、andards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterF519 Test Method for Mechanical Hydrogen Embrittlement Evaluation of Plating/Coating Processes and Ser
8、vice Environments3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 hydrogen pressure peakthe maximum hydrogen pressure value (see IH) obtained when the probe is heated followingcalibration, plating, or fluid testing.1 This test method is under the jurisdiction of ASTM Committee
9、F07 on Aerospace and Aircraft and is the direct responsibility of SubcommitteeeSubcommittee F07.04on Hydrogen Embrittlement.Current edition approved Nov. 1, 2012Dec. 1, 2017. Published November 2012January 2018. Originally approved in 1978. Last previous edition approved in 20062012as F326 96 (2006)
10、.(2012). DOI: 10.1520/F0326-96R12.10.1520/F0326-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This docum
11、ent is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as a
12、ppropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2 Symbols:3.2.1 HP = calibration hydrogen pressure peak.
13、3.2.2 HPp = plating hydrogen pressure peak.3.2.3 IE or Ie = probe cathode emission current.3.2.4 IH = probe hydrogen pressure.3.2.5 I = integral of I H curve from probe on to HP.3.2.6 lambda = time in seconds for hydrogen pressure peak to drop to half its value.3.2.7 = lambda obtained from a calibra
14、tion run.3.2.8 p = lambda obtained from a plating run.3.2.9 pc = normalized test lambda, obtained as follows:pc5p 40/! (1)3.2.10 pc = arithmetic average of normalized lambdas for a set of tests.3.2.11 range = difference between maximum pc and minimum pc for a given set of tests.3.2.12 run = calibrat
15、ion or plating of a probe.3.2.13 test = single evaluation of a plating solution for hydrogen embrittlement determination; run using a previously calibratedprobe.3.2.14 set of testsall consecutive tests on a plating solution for a given operator-instrument-day evaluation.3.2.15 windowtest surface of
16、a probe described in Fig. 1(A).4. Summary of Test Method4.1 This method uses a metal-shelled vacuum probe as an ion gage to evaluate electrodeposited cadmium characteristics relativeto hydrogen permeation. After calibration, a section of the probe shell is electroplated at the lowest current density
17、 encounteredin the cadmium electroplating process. During the subsequent baking of the probe at a closely controlled temperature, the probeion current, proportional to hydrogen pressure, is recorded as a function of time. From these data and the calibration data of theprobe, a number related to the
18、porosity of the electroplated metal relative to hydrogen is obtained.4.2 During the initial part of the bakeout, hydrogen continues to diffuse through the metal shell of the probe and the ion currentincreases. Within a short time, however, a maximum current is observed and then falls off as hydrogen
19、 is driven out of the system.4.3 Observations of the ion current-time curve indicate that the slope of the curve has an empirical relationship with failure dataon stress rupture specimens such as those in Test Method F519. For this method, I and variables (see Section 3) must beempirically correlate
20、d with results from the stress rupture specimens. This gives a quick means of measuring ease of bakinghydrogen out of cadmium-electroplated parts.4.4 Before an electroplating test, calibration is accomplished by electrolyzing the probe in a standard solution and baking it todetermine I and of the un
21、plated steel shell of the probe.5. Significance and Use5.1 Hydrogen is evolved during metal electrodeposition in aqueous baths. Some of this hydrogen enters parts during plating.If the absorbed hydrogen is at a level presenting embrittlement hazards to high-strength steel, it is removed by baking pa
22、rts afterplating to expel this hydrogen. However, the lack of plate porosity itself may block hydrogen egress. Thus, it becomes importantto know both the relative amount of hydrogen absorbed and the plate porosity.FIG. 1 Probe ConfigurationF326 1725.2 This test provides a quantitative control number
23、 for cadmium plate porosity that can be used to control a cadmium platingprocess and the status of cadmium-plated hardware. It can also be used for plating process troubleshooting and research anddevelopment to determine the effects on plate porosity by process variables, contaminants, and materials
24、. When used to controla critical process, control numbers for plate porosity must be determined by correlation with stress rupture specimens or otheracceptable standards.5.3 There is no prime standard for plate porosity. For this reason, two ovens must be used, with tests alternated between ovens.Da
25、ta from the ovens are compared to ensure no equipment change has occurred.6. Apparatus6.1 Hydrogen Detection InstrumentA system consisting of a control unit, two special ovens, auxiliary heater, recorder, testprobes, and associated equipment.6.2 OvenThe oven warms the probe to increase the hydrogen
26、diffusion rate into the probe. Oven parameters are selected byapparatus manufacturer to provide a standard reading for all hydrogen detection instruments.6.3 Oven StopperStopper covering the oven opening. Remove 10 s before inserting the probe.6.4 WindowThe window is the unpainted, bare steel portio
27、n of the probe, 0.63 6 0.03 in. in height, that is plated in thesolution under test. The window is shown in Fig. 1.6.5 Abrasive BlastAbrasive blast window area in the same way, using the same media, as used for the parts. Probe should berotated while being blasted to provide uniform surface.6.6 Elec
28、tronic Bakeout UnitThis heats the probe electrically to remove hydrogen absorbed into the probe after testing. Maybe part of hydrogen detection instrument.7. Reagents and Materials7.1 Reagents:7.1.1 Purity of ReagentsReagent grade chemicals shall be used in all tests. Unless otherwise indicated, it
29、is intended that allreagents conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society where suchspecifications are available.3 Other grades may be used, provided it is first ascertained that the reagent is of sufficient high purityto permit its use witho
30、ut lessening the accuracy of the determination.7.1.2 Acetone (C3H6O), technical.7.1.3 Anode Cleaning SolutionConcentrated nitric acid (HNO3), reagent grade.7.1.4 Cadmium Stripping SolutionAmmonium Nitrate (125 g/L)Dissolve 125 g of ammonium nitrate (NH4NO3, technical)in water and dilute to 1 L. Use
31、at room temperature.7.1.5 Calibration SolutionSodium Cyanide (50 g/L) Plus Sodium Hydroxide (50 g/L)Dissolve 50 g of sodium hydroxide(NaOH) in water. Add 50 g of sodium cyanide (NaCN) and dissolve. Dilute to 1 L. Use at 18 to 27C (65 to 80F).7.1.6 Water, Distilled or Deionized, minimum electrical re
32、sistivity 50 000 cm (for example, Specification D1193).7.2 Materials:7.2.1 Anodes (Calibration), solid-carbon arc rods, 5.1- to 12.7-mm (0.20- to 0.50-in.) 5.1 to 12.7 mm (0.20 to 0.50 in.) diameter.7.2.2 Anodes (Plating), cadmium rods, A-A-51126 6.4 to 12.7 mm (0.25 to 0.50 in.) thick, round or squ
33、are.7.2.3 Polytetrafluoroethylene (PTFE) TapeThe tape should be appropriate for use in solution, width about 12 to 19 mm,thickness small enough to seal.7.2.4 Glass 1-L Beaker.8. Hazards8.1 Sodium cyanide, cyanide, cadmium, nitric acid, and acetone can be health hazards. Use adequate face, hands, and
34、respiratory protection commensurate with standards established by American Conference of Government and Industrial Hygienefor these chemicals.9. Sampling9.1 Stir plating bath to ensure homogeneity. The plating bath sample must be representative of the bath. Obtain the sample frombeneath the surface
35、of the bath, not by skimming the surface. Chemical constituents must be within normal operating range.10. Preparation of Apparatus10.1 Plug in instrument and allow sufficient time for warmup.10.2 Turn on the oven and allow 4 h for warmup.3 Reagent Chemicals, American Chemical Society Specifications,
36、 American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial Convention, In
37、c. (USPC), Rockville, MD.F326 17310.3 Leave the instrument on continuously.10.4 Clean contaminated anodes in cleaning solution, (7.1.3) until heavy gassing is observed. (WarningSee Section 8.)11. Calibration of Apparatus11.1 Calibration Position, 1.08 6 0.2 A/dm2 (10 6 2 A/ft2)Use nominal dimensions
38、 of Fig. 1(A) for current calculations.11.2 Plating Position, 62 % of CurrentSet plating current density at the minimum value allowed by the plating specification.11.3 Probe Current, IeE, 6 6 0.2 mA.11.4 Electronic Probe Bakeout, 100 6 10 mA.11.5 Probe IH: 1 IH unit = 107 ALinearity, 62 % full scale
39、 within eachrange, 1 to 10 00011.6 OvensOvens are calibrated by the manufacturers against standard ovens that in turn were calibrated with notched tensionspecimen data. Oven stability is checked by comparing ovens against each other in duplicate tests.11.7 Correlation of OvensTo correlate ovens, det
40、ermine pc for all tests of a set (except tests discarded in accordance with13.4.4). From pc and the number of tests, determine from Fig. 2. Separate data and compute pc for each oven. Let pc (A) bethe higher value and pc (B) the lower value. Where pc (A) pc (B) is less than , the ovens are comparabl
41、e. Where pc (A) pc (B) is greater than , the ovens are not comparable.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 before bakeout.FIG. 2 Oven-Correlation LimitF326 17412.1.2 Insert a probe into the socket
42、of an electronic bakeout unit.12.1.3 Within 30 s, the heater should stabilize or be adjusted to 86.5616.5 mA. If the heater does not register current, the probeis defective and must be discarded.12.1.4 Bake out the probe for the time required to meet the limits in 12.2. Do not continuously bake out
43、probes for longer than2 h to preclude damaging paint.12.2 Probe CheckoutProbes that are new, or have been calibrated 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 1Here and throughout the specification, range s
44、ettings are for full-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 surface activation. If it is greater tha
45、n 1.0, screw on the capand insert probe into the oven.12.2.1.4 If I H is 0.5 or less within 5 min of inserting the probe into the oven, proceed to surface preparation. If the probe doesnot drop to IH = 0.5 or less with 5 min, bake out again. If three successive bakeouts do not reduce IH to 0.5 or le
46、ss within 5 minof insertion into the oven, discard the probe.12.2.1.5 Set the instrument to read IE. Probe IE should read 6.0 6 0.2 mA. If IE does not read or cannot be adjusted to this, theprobe or the instrument is defective. Check the instrument with other probes to determine which is defective.
47、Discard defectiveprobes.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 into the oven.12.2.2.4 Proceed as in 12.2.1, 12.2.1.4,
48、 and 12.2.1.5.12.3 Surface PreparationBefore the probe window preparation, check to ensure the window width and height above the probebase meet the requirements of Fig. 1(A). The probes having windows out of limits must be cleaned and repainted in accordancewith the suppliers instructions or discard
49、ed.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 of window with no paint being visible. Protect the base of the probe.Remove abrasive dust from the rubber masks to avoid paint damage.12.3.2 For processes using current densities under 4.32 A/dm2 (40 A/ft2), use production equipment to blast production parts.For processes with higher current densities, use laboratory blast equipm
