ASTM F326-96
(Test Method)Standard Test Method for Electronic Measurement for Hydrogen Embrittlement from Cadmium-Electroplating Processes
Standard Test Method for Electronic Measurement for Hydrogen Embrittlement from Cadmium-Electroplating Processes
SCOPE
1.1 This test method covers an electronic hydrogen detection instrument procedure for measurement of plating permeability to hydrogen. This method measures a variable related to hydrogen absorbed by steel during plating and to the hydrogen permeability of the plate during post plate baking. A specific application of this method is controlling cadmium-plating processes in which the plate porosity relative to hydrogen is critical, such as cadmium on high-strength steel.
1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific hazard statement, see Section 8.
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: F 326 – 96 An American National Standard
Standard Test Method for
Electronic Measurement for Hydrogen Embrittlement From
Cadmium-Electroplating Processes
This standard is issued under the fixed designation F 326; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 3.2.6 lambda 5 time in seconds for hydrogen pressure
peak to drop to half its value.
1.1 This test method covers an electronic hydrogen detec-
3.2.7 l5 lambda obtained from a calibration run.
tion instrument procedure for measurement of plating perme-
3.2.8 l 5 lambda obtained from a plating run.
p
ability to hydrogen. This method measures a variable related to
3.2.9 l 5 normalized test lambda, obtained as follows:
pc
hydrogen absorbed by steel during plating and to the hydrogen
permeability of the plate during post plate baking. A specific l 5l 40/l (1)
~ !
pc p
application of this method is controlling cadmium-plating
3.2.10 l 5 arithmetic average of normalized lambdas for
pc
processes where the plate porosity relative to hydrogen is
a set of tests.
critical, such as cadmium on high-strength steel.
3.2.11 range 5 difference between maximum l and mini-
pc
1.2 This standard does not purport to address all of the
mum l for a given set of tests.
pc
safety concerns, if any, associated with its use. It is the
3.2.12 run 5 calibration or plating of a probe.
responsibility of the user of this standard to establish appro-
3.2.13 test 5 single evaluation of a plating solution for
priate safety and health practices and determine the applica-
hydrogen embrittlement determination; run using a previously
bility of regulatory limitations prior to use. For specific hazard
calibrated probe.
statement, see Section 8.
3.2.14 set of tests—all consecutive tests on a plating solu-
1.3 The values stated in SI units are to be regarded as the
tion for a given operator-instrument-day evaluation.
standard. The values given in parentheses are for information
3.2.15 window—test surface of a probe described in Fig. 1a.
only.
4. Summary of Test Method
2. Referenced Documents
4.1 This method uses a metal-shelled vacuum probe as an
2.1 ASTM Standards:
ion gage to evaluate electrodeposited cadmium characteristics
D 1193 Specification for Reagent Water
relative to hydrogen permeation. After calibration, a section of
F 519 Method for Mechanical Hydrogen Embrittlement
the probe shell is electroplated at the lowest current density
Testing of Plating Processes and Aircraft Maintenance
encountered in the cadmium electroplating process. During the
Chemicals
subsequent baking of the probe at a closely controlled tem-
perature, the probe ion current, proportional to hydrogen
3. Terminology
pressure, is recorded as a function of time. From these data and
3.1 Definitions of Terms Specific to This Standard:
the calibration data of the probe, a number related to the
3.1.1 hydrogen pressure peak—the maximum hydrogen
porosity of the electroplated metal relative to hydrogen is
pressure value (see I ) obtained when the probe is heated
H
obtained.
following calibration, plating, or fluid testing.
4.2 During the initial part of the bakeout, hydrogen contin-
3.2 Symbols:
ues to diffuse through the metal shell of the probe and the ion
3.2.1 HP 5 calibration hydrogen pressure peak.
current increases. Within a short time, however, a maximum
3.2.2 HP 5 plating hydrogen pressure peak.
p
current is observed and then falls off as hydrogen is driven out
3.2.3 I 5 probe cathode emission current.
E
of the system.
3.2.4 I 5 probe hydrogen pressure.
H
4.3 Observations of the ion current-time curve indicate that
3.2.5 I 5 integral of I curve from probe on to HP.
g H
the slope of the curve has an empirical relationship with failure
data on stress rupture specimens such as those in Method
1 F 519. For this method I and l variables (see Section 3) must
g
This test method is under the jurisdiction of ASTM Committee F-7 on
Aerospace and Aircraft and is the direct responsibility of Subcommitteee F07.04 on be empirically correlated with results from the stress rupture
Hydrogen Embrittlement.
specimens. This gives a quick means of measuring ease of
Current edition approved Oct. 10, 1996. Published December 1996. Originally
baking hydrogen out of cadmium-electroplated parts.
e1
published as F 326 – 78. Last previous edition F 326 – 78 (1995)
Annual Book of ASTM Standards, Vol 11.01.
Annual Book of ASTM Standards, Vol 15.03.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
F 326
FIG. 1 Probe Configuration
4.4 Prior to an electroplating test, calibration is accom- 6.5 Abrasive Blast—Abrasive blast window area in the
plished by electrolyzing the probe in a standard solution and same way, using the same media, as used for the parts. Probe
baking it to determine I and l of the unplated steel shell of the should be rotated while being blasted to provide uniform
g
probe. surface.
6.6 Electronic bakeout unit—This heats the probe electri-
5. Significance and Use
cally to remove hydrogen absorbed into the probe after testing.
5.1 Hydrogen is evolved during metal electrodeposition in
May be part of hydrogen detection instrument.
aqueous baths. Some of this hydrogen enters parts during
7. Reagents and Materials
plating. If the absorbed hydrogen is at a level presenting
7.1 Reagents:
embrittlement hazards to high-strength steel, it is removed by
7.1.1 Purity of Reagents—Reagent grade chemicals shall be
baking parts after plating to expel this hydrogen. However, the
used in all tests. Unless otherwise indicated, it is intended that
lack of plate porosity itself may block hydrogen egress. Thus,
all reagents conform to the specifications of the Committee on
it becomes important to know both the relative amount of
Analytical Reagents of the American Chemical Society where
hydrogen absorbed and the plate porosity.
such specifications are available. Other grades may be used,
5.2 This test provides a quantitative control number for
provided it is first ascertained that the reagent is of sufficient
cadmium plate porosity that can be used to control a cadmium
high purity to permit its use without lessening the accuracy of
plating process and the status of cadmium-plated hardware. It
the determination.
can also be used for plating process troubleshooting and
7.1.2 Acetone (C H O), technical.
research and development to determine the effects on plate
3 6
7.1.3 Anode Cleaning Solution—Concentrated nitric acid
porosity by process variables, contaminants, and materials.
(HNO ), reagent grade.
When used to control a critical process, control numbers for
7.1.4 Cadmium Stripping Solution—Ammonium Nitrate
plate porosity must be determined by correlation with stress
(125 g/litre)—Dissolve 125 g of ammonium nitrate (NH NO ,
rupture specimens or other acceptable standards.
4 3
technical) in water and dilute to 1 L. Use at room temperature.
5.3 There is no prime standard for plate porosity. For this
7.1.5 Calibration Solution—Sodium Cyanide (50 g/L) plus
reason, two ovens must be used, with tests alternated between
Sodium Hydroxide (50 g/litre)—Dissolve 50 g of sodium
ovens. Data from the ovens are compared to ensure no
hydroxide (NaOH) in water. Add 50 g of sodium cyanide
equipment change has occurred.
(NaCN) and dissolve. Dilute to 1 L. Use at 18 to 27°C (65 to
6. Apparatus
80°F).
6.1 Hydrogen Detection Instrument—A system consisting 7.1.6 Water, Distilled or Deionized, minimum electrical
of a control unit, two special ovens, auxiliary heater, recorder, resistivity 50 000 V·cm. (for example, Specification D 1193)
test probes, and associated equipment. 7.2 Materials:
6.2 Oven—The oven warms the probe to increase the 7.2.1 Anodes (Calibration), solid-carbon arc rods, 5.1 to
hydrogen diffusion rate into the probe. Oven parameters are 1.27-mm (0.20 to 0.50-in.) diameter.
selected by apparatus manufacturer to provide a standard
7.2.2 Anodes (Plating), cadmium rods, QQ-A-671, 0.25 to
reading for all hydrogen detection instruments. 0.50 in. (6.4 to 12.7 mm) thick, round or square.
6.3 Oven Stopper—Stopper covering the oven opening.
7.2.3 Polytetrafluoroethylene (PTFE) Tape—The tape
Remove ten seconds before inserting the probe. should be appropriate for use in solution, width about 12 mm
6.4 Window—The window is the unpainted, bare steel
portion of the probe, 0.63 6 0.03 inch in height, that is plated
Reagent Chemicals, American Chemical Society Specifications, American
in the solution under test. The window is shown in Fig. 1.
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
A list of manufacturers of equipment and probes capable of performing these and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,
tests is available from ASTM Headquarters. MD.
F 326
to 19 mm, thickness small enough to seal. probe is defective and must be discarded.
7.2.4 Glass 1-L. Beaker. 12.1.4 Bake-out the probe for the time required to meet the
limits in 12.2. Do not continuously bake-out probes for longer
8. Hazards
than2hto preclude damaging paint.
8.1 Sodium cyanide, cyanide, cadmium, nitric acid, and
12.2 Probe Checkout—Probes that are new, or have been
acetone can be health hazards. Use adequate face, hands, and
calibrated or plated and stripped, need to be baked out to meet
respiratory protection commensurate with standards estab-
checkout requirements as follows:
lished by American Conference of Government and Industrial
12.2.1 Hot Probe:
Hygiene for these chemicals.
12.2.1.1 Set the range to 10.
9. Sampling
NOTE 1—Here and throughout the specification, range settings are for
full-scale reading.
9.1 Stir plating bath to ensure homogeneity. The plating
12.2.1.2 Remove the probe from the electronic bakeout unit;
bath sample must be representative of the bath. Obtain the
sample from beneath the surface of the bath, not by skimming plug into the socket and 15 6 1 s after removal from the
bakeout unit, turn the probe on.
the surface. Chemical constituents must be within normal
operating range. 12.2.1.3 Observe the peak value of I . If less than 1,
H
proceed with surface activation. If it is greater than 1.0, screw
10. Preparation of Apparatus
on the cap and insert probe into the oven.
10.1 Plug in instrument and allow sufficient time for warm-
12.2.1.4 If I is 0.5 or less within 5 min of inserting the
H
up.
probe into the oven, proceed to surface preparation. If the
10.2 Turn on the oven and allow 4 h for warm-up.
probe does not drop to I 5 0.5 or less with 5 min, bake-out
H
10.3 Leave the instrument on continuously.
again. If three successive bakeouts do not reduce I to 0.5 or
H
10.4 Clean contaminated anodes in cleaning solution,
less within 5 min of insertion into the oven, discard the probe.
(7.1.2) until heavy gassing is observed. Warning—
12.2.1.5 Set the instrument to read I . Probe I should read
E E
Precaution—See Section 8.
6.0 6 0.2 mA. If I does not read or cannot be adjusted to this,
E
the probe or the instrument is defective. Check the instrument
11. Calibration of Apparatus
with other probes to determine which is defective. Discard
11.1 Calibration Position, 1.08 6 0.2 A/dm (10 6 2
defective probes.
A/ft )—Use nominal dimensions of Fig. 1a for current calcu-
12.2.2 Cold Probe:
lations.
12.2.2.1 Set the range to 1.0.
11.2 Plating Position, 62 % of Current—Set plating cur-
12.2.2.2 Plug in the probe and turn on.
rent density at the minimum value allowed by the plating
12.2.2.3 Observe the peak value of I . If less than 0.2,
H
specification.
proceed to surface preparation. If greater than 0.2, insert into
11.3 Probe Current, I— ,6 6 2 mA.
e
the oven.
11.4 Electronic Probe Bakeout, 100 6 10 mA.
12.2.2.4 Proceed as in 12.2.1, 12.2.1.4, 12.2.1.5.
−7
11.5 Probe I : 1 I unit 5 10 A
H H
12.3 Surface Preparation—Prior to the probe window
Linearity,6 2 % full scale within each
preparation, check to ensure the window width and height
range, 1 to 10 000
above the probe base meet the requirements of Fig. 1a. The
11.6 Ovens—Ovens are calibrated by the manufacturers
probes having windows out of limits must be cleaned and
against standard ovens that in turn were calibrated with
repainted in accordance with the suppliers’ instructions or
notched tension specimen data. Oven stability is checked by
discarded.
comparing ovens against each other in duplicate tests.
12.3.1 Mask the probe to meet the requirement of Fig. 1b
11.7 Correlation of Ovens—To correlate ovens, determine
using conforming masks, supplied with instruments or PTFE
l¯ for all tests of a set (except tests discarded in accordance
pc
adhesive tape. Edges of masks must coincide with edges of
with 13.4.4). From l¯ and the number of tests, determine D
pc
window with no paint being visible. Protect the base of the
from Fig. 2. Separate data and compute l¯ for each oven. Let
pc
probe. Remove abrasive dust from the rubber masks to avoid
l¯ (A) be the higher value and l¯ (B) the lower value. Where
pc pc
paint damage.
l¯ (A)− l¯ (B) is less than D, the ovens are comparable.
pc pc
12.3.2 For processes using current densities under 4.32
Where l¯ (A)− l¯ (B) is greater than D, the ovens are not 2 2
pc pc
A/dm (40 A/ft ) use production equipment to blast production
comparable.
parts. For processes with higher current densities, use labora-
tory blast equipment. Dry abrasive blast the window area of the
12. Procedure
probe. Use material, size, air pressures, and distances repre-
12.1 Bakeout of Probe:
sentative of production blasting. Dry abrasive blast prior to
12.1.1 Strip cadmium-plated probes in stripping solution
calibration may be in a laboratory cabinet.
(7.1.3) and rinse in 50°C (122°F) water for 2 min prior to
bakeout.
NOTE 2—Some production facilities may not be adaptable to blasting of
probes. Special procedures will need to be approved by the procuring
12.1.2 Insert a probe into the socket of an electronic bakeout
agency.
unit.
12.1.3 Within 30 s, the heater should stabilize or be adjusted 12.3.3 Remove conformal blasting masks, ensuring that the
to 86.5 6 16.5 mA. If the heater does not register current, the window area is not touched. Remove loose abrasive by
F 326
FIG. 2 Oven-Correlation Limit
blowing off with filtered compressed air or by using a tissue 12.4.4 Wit
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.