ASTM E2792-21

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it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E2792 − 13 E2792 − 21
Standard Test Method for
Determination of Hydrogen in Aluminum and Aluminum
Alloys by Inert Gas Fusion
This standard is issued under the fixed designation E2792; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This test method applies to the determination of hydrogen in aluminum and aluminum alloys in concentrations mass fractions
from 0.05 mg/kg to 1 mg/kg.
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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
1.3 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E50 Practices for Apparatus, Reagents, and Safety Considerations for Chemical Analysis of Metals, Ores, and Related Materials
E135 Terminology Relating to Analytical Chemistry for Metals, Ores, and Related Materials
E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods
E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method
E1914 Practice for Use of Terms Relating to the Development and Evaluation of Methods for Chemical Analysis (Withdrawn
2016)
E2857 Guide for Validating Analytical Methods
3. Terminology
3.1 Definitions—For definitions of terms used in this test method, see Terminology E135 and Practice E1914.
4. Summary of Test Method
4.1 The specimen, contained in a high-purity graphite crucible, is heated to just below the melting point to drive off the surface
hydrogen. The sample is then heated to just beyond the melting point under a flowing carrier gas atmosphere. Hydrogen present
This test method is under the jurisdiction of ASTM Committee E01 on Analytical Chemistry for Metals, Ores, and Related Materials and is the direct responsibility of
Subcommittee E01.04 on Aluminum and Magnesium.
Current edition approved April 1, 2013Dec. 1, 2021. Published June 2013December 2021. Originally approved in 2011. Last previous edition approved in 20112013 as
E2792E2792 – 13.-11. DOI: 10.1520/E2791-13.10.1520/E2792-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
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E2792 − 21
in the sample is released as molecular hydrogen into the flowing gas stream. The released hydrogen is separated from other
liberated gases such as carbon monoxide (CO) and subsequently measured in a thermal conductivity cell.cell (Note 1).
4.2 Calibration is made using gas dosing with either helium or hydrogen or reference materials of known hydrogen content.
4.3 This test method is written for use with commercial analyzers equipped to carry out the above operations automatically.
NOTE 1—The current ILS data was gathered from technology described in this test method. Other units and detection systems exist that are not represented
here due to availability during the ILS. This test method provides guidance for appropriate use of these units, but users of other technologies should
perform in-house method validation per Guide E2857.
5. Significance and Use
5.1 This test method is intended for the routine testing of aluminum and aluminum alloys to qualitativelyquantitatively determine
the concentration mass fraction of hydrogen in aluminum and aluminum alloys. It is not intended to verify compliance with
compositional specifications because of the lack of certified reference materials. It is assumed that all who use this test method will
be trained analysts capable of performing common laboratory procedures skillfully and safely. It is expected that the work will be
performed in a properly equipped laboratory.
6. Interferences
6.1 The elements ordinarily present in aluminum and aluminum alloys do not interfere.
7. Apparatus
7.1 Fusion and Measurement Apparatus—Automatic hydrogen analyzer, consisting of an electrode furnace or induction furnace;
analytical gas stream; impurity removal systems; auxiliary purification systems and either a thermal conductivity cell hydrogen
measurement system cell, or an infrared hydrogen measurement system. Several models of commercial analyzers are available and
presently in use in industry. Each has its own unique design characteristics and operational requirements. Consult the instrument
manufacturer’s instructions for operational details.
7.2 Graphite Crucibles, machined from high-purity graphite. Use the crucible design(s) recommended by the manufacturer of the
instrument.
7.3 Quartz Crucibles, for analysis of steel reference materials on some instrument types. Use the crucible design(s) recommended
by the manufacturer of the instrument.
7.4 Crucible Tongs, capable of handling recommended crucibles.
8. Reagents and Materials
8.1 Acetone—Reagent Grade or ACS certified grade or higher purity.
8.2 Ethyl Alcohol—Reagent Grade or ACS certified grade or higher purity.
8.3 Isopropyl Alcohol—Reagent Grade or ACS certified grade or higher purity.
8.4 Sodium Hydroxide NaOH on ClayClay. (Commonly known as Ascarite II).
8.5 High-Purity Gas (99.99 %)—Argon, nitrogen, and helium or hydrogen (Note 12).
NOTE 2—Carrier and dosing gases vary by instrument model and include high-purity argon, nitrogen, helium, or hydrogen. Gas purity requirements shall
be specified by the instrument manufacturer.
8.6 Magnesium Perchlorate (commonly(MgClO , commonly known as Anhydrone).
E2792 − 21
8.7 Molecular Sieve, as specified by the instrument manufacturer.
8.8 Schutze Reagent—Iodine pentoxide (I O ) on granular silica, purity as specified by the instrument manufacturer.
2 5
8.9 Copper Wire, to convert CO to CO in thermal conductivity cell instruments. Characteristics should be specified by the
instrument manufacturer.
8.10 Glass wool,Wool, used to pack reagents.
™
8.11 OMI Purifier Tube—Organolithium polymer used by some instruments to remove O , water vapor, CO, CO , most sulfur
2 2
compounds, most halogen compounds, alcohols, and phenols to less than 1010 ng ppb ⁄g from the carrier gas.
9. Hazards
9.1 Refer to Practices E50 for potential hazards present when using this test method.
9.2 Use care when handling hot crucibles and operating electrical equipment to avoid personal injury by either burn or electrical
shock.
10. Preparation of Apparatus
10.1 Assemble the apparatus as recommended by the manufacturer.
10.2 Provide the manufacturer’s recommended electrical power and gas requirements. Prepare the apparatus for operation in
accordance with the instrument manufacturer’s recommendations.
10.3 Set the instrument to the operational mode in accordance with the instrument manufacturer’s recommendations.
10.4 Test the furnace and analyzer to ensure that the gas stream meets manufacturer’s requirements for acceptable leak rate.
10.5 Optimize the crucible pretreatment power settings (commonly called outgas), the surface and analysis power settings,
crucible pretreatment time and analysis integration time for aluminum alloys.
10.5.1 Most manufacturers offer application guidance on appropriate settings to achieve optimum performance for aluminum
alloys. Refer to this application guidance literature for assistance in determining optimum settings.
10.5.2 If the instrument is capable; optimize the crucible pretreatment time and power settings to achieve a stable blank (see
12.2.2).
10.5.3 If the instrument is capable;capable, optimize the analysis time and power settings to obtain the optimum signal to noise
ratio for the analysis of aluminum alloys.
10.5.4 It will not be necessary to regularly optimize the analysis set-up routinely. set-up. Store the settings into the instrument
hardware or software for routinefrequent use.
11. Sampling and Sample Preparation
11.1 Samples can be taken either from molten aluminum during casting or from the appropriate areas of finished product.
11.1.1 Samples from molten aluminum should be taken using the procedure described by Ransley and Talbot. Briefly, a ladle is
C.E. Ransley and D.E.J. Talbot, Ransley, C. E., and Talbot, D. E. J., "The Routine Determination of the Hydrogen Content of Aluminum and Aluminum Alloys by the
Hot-Extraction Method".Method,” Journal of the Institute of Metals, Vol.Vol 84, 1955-1956, p. 445.
E2792 − 21
used to pour molten metal into a copper sampler that is designed to minimize porosity, cracks, voids, pits, and other defects that
may lead to erroneously high hydrogen results.
11.1.2 Samples from Cast or Finished Product—Samples from cast or finished product should be taken from an area that
represents the nominal concentration mass fraction of hydrogen in the piece being sampled. Hydrogen may segregate in product
and may also accumulate around defects sometimes making it difficult to obtain a representative sample. It is incumbent on the
user to insureensure that the area selected for sampling is satisfactory. A cubical piece should be cut from the product using a saw
with a clean blade. Carbide tipped blades are recommended. The size of the cube needed depends on the final sample size required
for the instrument.
11.2 Samples must be of an appropriate size to fit into the graphite crucible. In general, the sample should be as close to the
maximum size for the crucible as possible. A sample sizemass of at least 4 grams 4 g is recommended. Smaller samples may be
analyzed,analyzed; however, the amount of hydrogen generated will be smaller and the detection limit will be higher. Smaller
samples also have a higher surface to bulk hydrogen ratio and the method parameters may not be ideal for separating the surface
hydrogen from the bulk hydrogen.
11.3 The sample should be machined using a lathe or milling machine to the manufacturers recommended specifications. A fine
surface is important for obtaining accurate results. Rough surfaces may lead to excessively high surface readings and may, in
extreme cases, cause high bulk results. Diamond tipped tool bits and use of ethyl alcohol or isopropyl alcohol lubricant during
machining may be used to improve the surface finish. The average surface roughness for samples machined using a diamond tipped
tool bit and alcohol lubricant is typically 40 micro inches to 50 micro inches. Surface area of the sample will increase as the surface
roughness increases. Increased surface area will result in higher surface hydrogen readings, and in extreme cases, may affect the
bulk hydrogen analysis.
11.4 Specimens must be handled with crucible tongs or in a manner that prevents surface contamination. Samples may be rinsed
in acetone, ethyl alcohol, or isopropyl alcohol if surface contamination is suspected.
12. Calibration
12.1 Calibration can be done by two different methods;methods: gas dosing or by the use of certified reference materials. Most
instruments used for the analysis of hydrogen in aluminum alloys are calibrated by gas dosing due to the lack of certified reference
materials for hydrogen in aluminum.
12.2 Blank Determination Procedure:
12.2.1 Both gas dose and reference material calibration require an accurate blank determination. The blank value may be included
in the calibration curve or subtracted from all subsequent determinations.
12.2.2 Make at least three blank determinations using an empty graphite crucible following the manufacturer’s guidelines.
12.2.3 If the average blank value exceeds 0.000 mg/kg 6 0.005 mg/kg then determine the cause, make necessary corrections,
andstandard deviation of three consecutive blank determinations exceeds 0.005 mg/kg, or the blank readings are too high, repeat
12.2.2. Refer to the instrument manufacturer’s instructions concerning the troubleshooting and correction of blank determinations
not meeting the above criterion.
12.2.4 Enter the average blank value in into the instrument
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