ASTM F1940-07a
Standard Test Method for Process Control Verification to Prevent Hydrogen Embrittlement in Plated or Coated Fasteners
- Standard No.
- ASTM F1940-07a
- Release Date
- 2007
- Published By
- American Society for Testing and Materials (ASTM)
- Status
- Replace By
- ASTM F1940-07a(2014)
- Latest
- ASTM F1940-07a(2019)
- Scope
This test method establishes a means to verify the prevention, to the extent possible, of IHE in steel fasteners during manufacture by maintaining strict controls during production operations such as surface preparation, pretreatments, and plating or coating. It is intended to be used as a qualification test for new or revised plating or coating processes and as a periodic inspection audit for the control of a plating or coating process.
Passing this test allows fasteners to be stressed in tension to the minimum specified tensile load in air with almost no possibility of time delayed fracture in air as a result of IHE from processing. If the amount of residual hydrogen is not sufficient to induce cracking or fracture in the specimen under worst case conditions, then it can be concluded that all of the lots of fasteners processed during that period will not have sufficient residual hydrogen from processing to induce hydrogen embrittlement of the fasteners under stress in air if the process remains in control, unchanged and stable.
If certified specimens with demonstrated sensitivity to IHE, processed with the fasteners, have a threshold ≥75 % of the incremental step load notched bend fracture stress, NFS(B)F 1624, it is assumed that all fasteners processed the same way during the period will also pass any sustained load IHE test.
FIG. 1 Dimensional Requirements for a 0.4W-Notched Square Bar Bend Specimen1.1 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 consists of a mechanical test, conducted on a standard specimen used as a witness, for the evaluation and control of the potential for IHE that may arise from various sources of hydrogen in a plating or coating process.
1.3 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 evaluating processes used for plating or coating ferrous fasteners.
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 K
t = 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 The test is an accelerated (24 h) test method to measure the threshold for hydrogen stress cracking, and i......
ASTM F1940-07a history
- 2019 ASTM F1940-07a(2019) Standard Test Method for Process Control Verification to Prevent Hydrogen Embrittlement in Plated or Coated Fasteners
- 2007 ASTM F1940-07a(2014) Standard Test Method for Process Control Verification to Prevent Hydrogen Embrittlement in Plated or Coated Fasteners
- 2007 ASTM F1940-07a Standard Test Method for Process Control Verification to Prevent Hydrogen Embrittlement in Plated or Coated Fasteners
- 2007 ASTM F1940-07 Standard Test Method for Process Control Verification to Prevent Hydrogen Embrittlement in Plated or Coated Fasteners
- 2001 ASTM F1940-01 Standard Test Method for Process Control Verification to Prevent Hydrogen Embrittlement in Plated or Coated Fasteners
- 1999 ASTM F1940-99 Standard Test Method for Process Control Verification to Prevent Hydrogen Embrittlement in Plated or Coated Fasteners