ASTM F1940-07
(Test Method)Standard Test Method for Process Control Verification to Prevent Hydrogen Embrittlement in Plated or Coated Fasteners
Standard Test Method for Process Control Verification to Prevent Hydrogen Embrittlement in Plated or Coated Fasteners
SCOPE
1.1 This test method covers a procedure to prevent, to the extent possible, internal hydrogen embrittlement (IHE) of fasteners by monitoring the plating or coating process, such as those described in Specifications F 1137 and F 1941. The process is quantitatively monitored on a periodic basis with a minimum number of specimens as compared to qualifying each lot of fasteners being plated or coated. Trend analysis is used to ensure quality as compared to statistical sampling analysis of each lot of fasteners. This test method consists of a mechanical test for the evaluation and control of the potential for IHE that may arise from various sources of hydrogen in a plating or coating process.
1.2 This test method applies to externally threaded tensile fasteners that can also be loaded in bending during installation.
1.3 This test method is limited to evaluating hydrogen induced embrittlement due only to processing (IHE) and not due to environmental exposure (EHE, see Test Method F 1624).
1.4 This test method is not intended to measure the relative susceptibility of steels to either IHE or EHE.
1.5 This test method is limited to ferrous fasteners that are susceptible to time-delayed fracture caused by the diffusion of hydrogen under stress.
1.6 This test method uses a notched square bar specimen that conforms to Test Method F 519, Type 1e, except that the radius is increased to accommodate the deposition of a larger range of platings and coatings. For the background on Test Method F 519 testing, see publications ASTM STP 543 and ASTM STP 962. The stress concentration factor is at a Kt = 3.1 ± 0.2. The sensitivity is demonstrated with a constant imposed cathodic potential to control the amount of hydrogen. Both the sensitivity and the baseline for residual hydrogen will be established with tests on bare metal specimens in air.
1.7 The sensitivity of each lot of specimens to IHE shall be demonstrated. A specimen made of AISI E4340 steel heat treated to a hardness range of 50 to 52 HRC is used to produce a "worst case" condition and maximize sensitivity to IHE.
1.8 A notched four-point bend specimen undergoes sustained load and slow strain rate testing by using incremental loads and hold times under displacement control to measure a threshold stress in an accelerated manner in accordance with Test Method F 1624. The test is an accelerated (≤24 h) incrementally increasing step load test method that measures the threshold for hydrogen stress cracking that is used to quantify the amount of residual hydrogen in the specimen.
1.9 In this test method, bending is used instead of tension because it produces the maximum local limit load tensile stress in a notched bar of up to 2.3 times the yield strength as measured in accordance with Test Method E 8. A fastener that is unintentionally exposed to bending on installation may attain this maximum local tensile stress.
1.10 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.11 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.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn. Contact ASTM
International (www.astm.org) for the latest information.
Designation: F 1940 – 07
Standard Test Method for
Process Control Verification to Prevent Hydrogen
1
Embrittlement in Plated or Coated Fasteners
This standard is issued under the fixed designation F1940; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope Boththesensitivityandthebaselineforresidualhydrogenwill
be established with tests on bare metal specimens in air.
1.1 This test method covers a procedure to prevent, to the
1.7 The sensitivity of each lot of specimens to IHE shall be
extent possible, internal hydrogen embrittlement (IHE) of
demonstrated. A specimen made of AISI E4340 steel heat
fasteners by monitoring the plating or coating process, such as
treatedtoahardnessrangeof50to52HRCisusedtoproduce
those described in Specifications F1137 and F1941. The
a “worst case” condition and maximize sensitivity to IHE.
process is quantitatively monitored on a periodic basis with a
1.8 A notched four-point bend specimen undergoes sus-
minimumnumberofspecimensascomparedtoqualifyingeach
tained load and slow strain rate testing by using incremental
lotoffastenersbeingplatedorcoated.Trendanalysisisusedto
loads and hold times under displacement control to measure a
ensure quality as compared to statistical sampling analysis of
threshold stress in an accelerated manner in accordance with
eachlotoffasteners.Thistestmethodconsistsofamechanical
Test Method F1624. The test is an accelerated (#24 h)
test for the evaluation and control of the potential for IHE that
incrementally increasing step load test method that measures
may arise from various sources of hydrogen in a plating or
the threshold for hydrogen stress cracking that is used to
coating process.
quantify the amount of residual hydrogen in the specimen.
1.2 This test method applies to externally threaded tensile
1.9 In this test method, bending is used instead of tension
fastenersthatcanalsobeloadedinbendingduringinstallation.
becauseitproducesthemaximumlocallimitloadtensilestress
1.3 This test method is limited to evaluating hydrogen
in a notched bar of up to 2.3 times the yield strength as
induced embrittlement due only to processing (IHE) and not
measured in accordance with Test MethodE8.Afastener that
due to environmental exposure (EHE, see Test Method
isunintentionallyexposedtobendingoninstallationmayattain
F1624).
this maximum local tensile stress.
1.4 This test method is not intended to measure the relative
1.10 The values stated in inch-pound units are to be re-
susceptibility of steels to either IHE or EHE.
garded as standard. The values given in parentheses are
1.5 This test method is limited to ferrous fasteners that are
mathematical conversions to SI units that are provided for
susceptible to time-delayed fracture caused by the diffusion of
information only and are not considered standard.
hydrogen under stress.
1.11 This standard does not purport to address all of the
1.6 This test method uses a notched square bar specimen
safety concerns, if any, associated with its use. It is the
that conforms to Test Method F519, Type 1e, except that the
responsibility of the user of this standard to establish appro-
radius is increased to accommodate the deposition of a larger
priate safety and health practices and determine the applica-
range of platings and coatings. For the background on Test
2 bility of regulatory limitations prior to use.
Method F519 testing, see publications ASTM STP 543 and
3
ASTM STP 962. The stress concentration factor is at a K =
t
2. Referenced Documents
3.1 6 0.2. The sensitivity is demonstrated with a constant
4
2.1 ASTM Standards:
imposed cathodic potential to control the amount of hydrogen.
D1193 Specification for Reagent Water
E4 Practices for Force Verification of Testing Machines
1
This test method is under the jurisdiction of ASTM Committee F16 on E8 Test Methods for Tension Testing of Metallic Materials
Fasteners and is the direct responsibility of Subcommittee F16.93 on Quality
E18 Test Methods for Rockwell Hardness of Metallic
Assurance Provisions for Fasteners.
Materials
Current edition approved May 1, 2007. Published May 2007. Originally
published as approved in 1998. Last previous edition approved in 2001 as
F1940–01.
2 4
Hydrogen Embrittlement Testing, ASTM STP 543, American Society for For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Testing and Materials, 1974. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
3
Hydrogen Embrittlement; Prevention and Control, ASTM STP 962, American Standards volume information, refer to the standard’s Document Summary page on
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.