1、Designation: F 1113 87 (Reapproved 2005)e1Standard Test Method forElectrochemical Measurement of Diffusible Hydrogen inSteels (Barnacle Electrode)1This standard is issued under the fixed designation F 1113; the number immediately following the designation indicates the year oforiginal adoption or, i
2、n the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.e1NOTEEditorial changes were made throughout in June 2005.1. Scope1.1 This test method covers
3、 the procedure for measuringdiffusible hydrogen in steels by an electrochemical method.1.2 This test method is limited to carbon or alloy steels,excluding austenitic stainless steels.1.3 This test method is limited to flat specimens to whichthe cell can be attached (see 4.6 and 4.8).1.4 This test me
4、thod describes testing on bare or plated steelafter the plate has been removed (see 4.4).1.5 This test method is limited to measurements at roomtemperature, 20 to 25C (68 to 77F).1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is therespon
5、sibility 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.2. Referenced Documents2.1 ASTM Standards:2B 183 Practice for Preparation of Low-Carbon Steel forElectroplatingB 242 Practice for Prepar
6、ation of High-Carbon Steel forElectroplatingB 766 Specification for Electrodeposited Coatings of Cad-miumD 1193 Specification for Reagent WaterF 519 Test Method for Mechanical Hydrogen Embrittle-ment Evaluation of Plating Processes and Service Environ-mentsG3 Practice for ConventionsApplicable to El
7、ectrochemicalMeasurements in Corrosion Testing3. Summary of Test Method3.1 A hydrogen-containing part is made the anode in anelectrochemical cell. The diffusible (atomic) hydrogen, whichcomes to the metal-electrolyte interface, is oxidized to protons(H+); H+combines with hydroxyl ions (OH) in the el
8、ectrolyteto form water. The oxidation current is measured and related tothe hydrogen concentration.4. Significance and Use4.1 The critical level of hydrogen in steels is that hydrogenwhich can build up to high concentrations at points of hightriaxial stress causing embrittlement of the steel which c
9、an leadto catastrophic damage. This hydrogen can enter by variousmeans, such as during pickling and electroplating. Means ofreducing this hydrogen during processing are given in Speci-fication B 766 and Practices B 183 and B 242. It is stillnecessary, however, to know how effective these methods are
10、.Though the ultimate reason for measuring this hydrogen is torelate it to embrittlement, this is not within the scope of this testmethod. As susceptibility to hydrogen embrittlement is afunction of alloy type, heat treatment, intended use,and soforth, the tolerance for hydrogen must be determined by
11、 theuser according to Method F 519.4.2 Though the actual hydrogen concentration is not deter-mined in this test method, the current densities have beenshown to be useful as an indication of relative hydrogenconcentrations (1-3),3and therefore the degree of hydrogenembrittlement (1,2). Thus, measurem
12、ents can be compared toone another (see 4.1 and 7.1).4.3 This test method is applicable as a quality control toolfor processing (such as to monitor plating and baking) or tomeasure hydrogen uptake caused by corrosion.4.4 This test method is nondestructive; however, if there isa coating, it must be r
13、emoved by a method which has beendemonstrated to neither damage the steel nor introduce hydro-gen to make the measurement.1This test method is under the jurisdiction of ASTM Committee F07 onAerospace and Aircraft and is the direct responsibility of Subcommittee F07.04 onHydrogen Embrittlement.Curren
14、t edition approved June 1, 2005. Published June 2005. Originallyapproved in 1987. Last previous edition approved in 1999 as F 1113 87 (1999).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volu
15、me information, refer to the standards Document Summary page onthe ASTM website.3Boldface numbers in parentheses refer to the list of references at the end of thisstandard.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.5 This test
16、 method is also applicable to situations produc-ing continuous hydrogen permeation, such as high pressurehydrogen cylinders or corrosion processes. The results, how-ever, would require a different treatment and interpretation (4).4.6 This test method is also applicable to small parts, suchas fastene
17、rs. The technique, procedure, and interpretationwould, however, have to be altered.4.7 Use of this test method on austenitic stainless steels andother face centered cubic (FCC) alloys would require differentmeasurement times and interpretation of results because ofdiffering kinetics.4.8 This test me
18、thod can be used on slightly curved surfacesas long as the gasket defines a reproducible area. The areacalculation must, however, be changed.5. Apparatus5.1 CellA photo and drawing of a typical cell, which hasbeen found to be acceptable for hydrogen measurements, areshown in Figs. 1 and 2, respectiv
19、ely.5.1.1 The cell is made of a nonmetallic material that will notreact with or contaminate the solution. The side opening has arecess to accommodate the silicone rubber gasket.5.1.2 Gasket, silicone rubber, shall provide a reproduciblesolution-contact area with the specimen, preferably 1.0 cm2.5.1.
20、3 Cell Holder, a cradle-like C-clamp. Other clampingdevices can be used if necessary, such as for larger parts.5.1.4 Cathode, a nickel/nickel oxide electrode. It is made byremoving the positive plate from a nickel/cadmium battery andattaching a nickel wire or foil. The area of this cathode shall bea
21、pproximately five times that of the anode.5.1.5 AnodeThe anode is the specimen.5.1.6 The cell is left open to the atmosphere. No purging isused.5.2 Current Measuring DeviceThe current can be mea-sured by any method that will not affect its value. A zeroresistance ammeter (5), a current follower (6),
22、 and the currentmeasuring system shown in Fig. 3 (1) have been found to beacceptable. The following description refers to Fig. 3.5.2.1 Standard Resistor, connected across the cell through aswitch.5.2.2 Electrometer, to determine the current by measuringthe voltage drop across the resistor. A 10-kV r
23、esistor with anFIG. 1 Photograph of CellFIG. 2 Engineering Drawing of Cell (3)FIG. 3 Schematic of Measuring Apparatus (1)F 1113 87 (2005)e12electrometer having an input impedance of 1012V and a 1-mAoutput has been found to be satisfactory.5.2.3 Strip Chart Recorder, to monitor the electrometeroutput
24、. A recorder having an input resistance of 100 kV hasbeen found to be satisfactory.5.2.4 Timer, accurate to within 10 s in a 30-min run.6. Reagents6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the
25、 specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.4Other grades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determina
26、tion.6.2 Purity of WaterDistilled or deionized water conform-ing to Specification D 1193, Type IV, shall be used to prepareall solutions.6.3 Sodium Hydroxide Solution (0.2M)Dissolve8gofsodium hydroxide (NaOH) pellets in water and dilute to 1 L.6.4 Ammonium Nitrate Solution (120 g/L)Dissolve 120 gof
27、ammonium nitrate (NH4NO3) in water and dilute to 1 L.6.5 Methyl Alcohol (CH3OH).6.6 Ethyl Alcohol (C2H5OH).7. Test Specimens7.1 The test specimen can be a coupon of 1- to 6-mmthickness or an actual part. If it is a coupon, it shall be of thesame alloy, form, temper/condition, and surface finish as t
28、hepart. The specimen shall be of sufficient size to accommodatethe cell and of sufficient smoothness and flatness to preventleaking of the electrolyte under the gasket (see 8.2). If possible,specimens shall be of sufficient size for a duplicate measure-ment to be made (see 9.4).8. Calibration and St
29、andardization8.1 Calibrate the nickel/nickel oxide (Ni/NiO) electrodeagainst a saturated calomel electrode (SCE) in 0.2M NaOH. Afreshly charged Ni/NiO electrode will be at least 350 mVpositive to the SCE when measured according to Practice G3.It shall be recharged when its potential is less than 300
30、 mVpositive to the SCE.NOTE 1Repeated use of the Ni/NiO electrode will cause a temporarydrain of the charge. To prevent this from happening, alternate twoelectrodes during a series of measurements.8.1.1 Charge the Ni/NiO electrode in a 0.2M NaOH solutionfor12 h at a current density of 5 to 10 mA/cm2
31、.8.1.2 The Ni/NiO electrode is made the anode, that is,connected to the positive terminal of the charging source. Anyconductor that will not react with the solution, such asplatinum, graphite, or steel, may be used as the cathode.8.2 Determine the specimen contact area which is outlinedby the gasket
32、.8.2.1 Assemble the cell with a smooth piece of aluminumsheet or foil, at least 0.04 mm thick, between a specimen andthe gasket. The Ni/NiO electrode is not needed.8.2.2 Fill the cell with 0.2M NaOH solution and allow thealuminum to be etched by the alkaline solution for about 20min.8.2.3 Dismantle
33、the cell and rinse well. A properly as-sembled cell will produce a sharply defined, circular etch (seeFig. 4).8.2.4 Measure the diameter of the etched circle under amicroscope (103), and calculate the area (see 10.2).8.2.5 A poor gasket or improper tightening of the cell willbe detected by this proc
34、edure. Overtightening will produce adeformation of the gasket, resulting in an out-of-round etch.Undertightening, or a worn-out gasket, will cause crevices,resulting in etching under the gasket (see Fig. 4).8.3 Measure uncoated coupons, prepared in accordancewith 7.1, to determine the background cur
35、rent density. Keepthese coupons desiccated for at least one week before measur-ing, to assure that no hydrogen, as a result of corrosion, isproduced, and to allow any hydrogen in the specimens toescape.NOTE 2The background measurement is used only as a reference toindicate the presence or absence of
36、 hydrogen. It is not used in anycalculation.9. ProcedureNOTE 3This procedure pertains to cadmium-plated specimens. Anyother plating must be removable by a method that will neither damage thesteel nor introduce hydrogen.9.1 Specimen Preparation:NOTE 4The time to prepare the specimen must take no long
37、er than 5min.9.1.1 Remove any cadmium plate from an area on one sideof the specimen large enough to accommodate the cell (ap-proximately 40 by 40 mm) by swabbing with ammoniumnitrate solution. Rinse with water and dry. Swabs made ofpolyurethane foam or cotton have been found to be satisfac-tory.9.1.
38、2 Abrade the surface lightly with an aluminum oxide-impregnated nylon cleaning pad to remove surface contamina-tion and to provide a reproducible surface finish. Wipe cleanusing a tissue wet with methyl or ethyl alcohol.9.2 Cell Assembly:4Reagent Chemicals, American Chemical Society Specifications,
39、AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc.
40、(USPC), Rockville,MD.FIG. 4 Etched Areas (NaOH on Al) Showing (A) Good Gasket Fitand (B) Poor Fit Showing Undercutting of Gasket as a Result ofUndertightening or Worn GasketF 1113 87 (2005)e13NOTE 5The time to assemble the cell and start the measurement musttake no longer than 5 min. The total time
41、from the start of 9.1.1-9.3.1 musttake no longer than 10 min.9.2.1 Clamp the Cell to the Specimen.NOTE 6The cell should be clamped only tight enough to preventleakage. Overtightening will cause deformation of the gasket. Propertightening can be determined by following the procedure in 8.2.9.2.2 Clam
42、p the Ni/NiO electrode in the center of the cellcavity using the cell dimensions of Fig. 1. For other celldesigns, the distance between the electrodes shall be 25 mm.9.2.3 Connect the resistor and switch between the Ni/NiOelectrode and the specimen.9.2.4 Connect the electrometer across the resistor
43、so that theNi/NiO electrode will measure positive and the steel negative.9.2.5 Connect the recorder to the electrometer output.9.2.6 Fill the cell with 0.2M NaOH, making sure that theNi/NiO electrode and the specimen measurement area arecompletely covered with solution.9.3 Making the Measurement:NOT
44、E 7The measurement must be started within 1 min of filling thecell.9.3.1 Simultaneously turn on the cell switch and the timer.NOTE 8The oxidation current decreases with time. During the mea-surement, it will change by a few orders of magnitude. Therefore, for thefirst 5 min, set the recorder at an a
45、ppropriate high setting to preventoverload. The final readings will be in the microampere range. Adjust theelectrometer and recorder accordingly.9.3.2 Record the current at the end of 30 min. This shall bereferred to as the 30-min reading.NOTE 9The current measurement must always be made for the sam
46、elength of time. In this test method, 30 min has been chosen. The reasonsfor this are given in references (1,3).9.3.3 Turn off the switch.9.3.4 Dismantle the cell, rinse, and dry.9.4 Repeat Measurements:NOTE 10If the recorder tracing is poor (see Fig. 5), a repeatmeasurement must be made.9.4.1 If ca
47、dmium-plated coupons or parts are of sufficientsize, make duplicate measurements on the same specimen,either alongside or opposite to the first in accordance with 9.1.If alongside, the newly swabbed area shall not overlap the first.The specimen preparation procedure in 9.1.1 must be started nomore t
48、han 10 min after completion of the previous measure-ment taken in 9.3.2.9.4.2 If a series of measurements are to be made during theday, alternate Ni/NiO electrodes and gaskets must be used.Allow at least 45 min between runs using the same ones.10. Calculation10.1 Calculate the current from the volta
49、ge drop across thestandard resistor using Ohms law, I = E/R. For example, if thefull-scale voltage on the strip chart recorder is 10 mV and theresistance is 10 kV, then the full-scale current is 1 A.10.2 Calculate the contact area from the diameter of theetched surface (see 8.2). The diameter, D, should be measuredin two directions and averaged. If it has been established thatthe contact area is essentially round, the area, A, is given by:A = p (D/2)2. For example, if the average diameter is found tobe 1.2 cm, the area is 3.14 (1.2/2)2or 1.10 cm2.10.3 Curren
