ASTM B839-94(2003)
(Test Method)Standard Test Method for Residual Embrittlement in Metallic Coated, Externally Threaded Articles, Fasteners, and Rod—Inclined Wedge Method
Standard Test Method for Residual Embrittlement in Metallic Coated, Externally Threaded Articles, Fasteners, and Rod—Inclined Wedge Method
SCOPE
1.1 This test method covers the determination of, on a statistical basis, the probability of the existence of hydrogen embrittlement or degradation in:
1.1.1 A batch of barrel electroplated, autocatalytic plated, phosphated, or chemically processed threaded articles or fasteners and
1.1.2 A batch of rack plated threaded articles, fasteners, or rod.
1.2 Industrial practice for threaded articles, fasteners, and rod has evolved three graduated levels of test exposure to ensure reduced risk of hydrogen embrittlement (see Section 3). These levels have evolved from commercial applications having varying levels of criticality. In essence, they represent the confidence level that is required. They also represent the time that finished goods are held before they can be shipped and used. This time equates to additional cost to the manufacturer that may of necessity be added to the cost of the finished goods.
1.3 This test method is applicable to threaded articles, fasteners, and rod made from steel with ≥1000 MPa (with corresponding hardness values of 300 HV10 kgf, 303 HB, or 31 HRc) or surface hardened threaded articles, fasteners, or rod.
1.4 This test method shall be carried out after hydrogen embrittlement relief heat treatment in accordance with the requirements of Guide B 850. It may also be used for assessing differences in processing solutions, conditions, and techniques. This test method has two main functions: first, when used with a statistical sampling plan it can be used for lot acceptance or rejection, and second, it can be used as a control test to determine the effectiveness of the various processing steps including pre- and post-baking treatments to reduce the mobile hydrogen in the articles, fasteners, or rod. While this test method is capable of indicating those items that are embrittled to the extent defined in Section 3, it does not guarantee complete freedom from embrittlement.
1.5 This test method does not relieve the processor from imposing and monitoring suitable process control.
1.6 This test method has been coordinated with ISO/DIS 10587 and is technically equivalent. (Warning—Great care should be taken when applying this test method. The heads of embrittled articles, fasteners, or rod may suddenly break off and become flying projectiles capable of causing blindness or other serious injury. This hazard can occur as long as 200 h after the test has started. Hence, shields or other apparatus should be provided to avoid such injury.)
Note 1—The use of inhibitors in acid pickling baths does not necessarily guarantee avoidance of hydrogen embrittlement.
1.7 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.
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Designation: B 839 – 94 (Reapproved 2003)
Standard Test Method for
Residual Embrittlement in Metallic Coated, Externally
Threaded Articles, Fasteners, and Rod—Inclined Wedge
Method
This standard is issued under the fixed designation B 839; 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.
INTRODUCTION
When atomic hydrogen enters steels and certain other alloys, it can cause loss of ductility or load
carrying ability or cracking (usually as submicroscopic cracks), or catastrophic brittle failures at
applied stresses well below the yield strength or even the normal design strength for the alloys. This
phenomenon often occurs in alloys that show no significant loss in ductility, when measured by
conventional tensile tests, and is frequently referred to as hydrogen-induced delayed brittle failure,
hydrogen stress cracking, or hydrogen embrittlement. The hydrogen can be introduced during
cleaning, pickling, phosphating, electroplating, autocatalytic processes, and in the service environment
as a result of cathodic protection reactions or corrosion reactions. Hydrogen can also be introduced
during fabrication, for example, during roll forming, machining, and drilling due to lubricant
breakdown as well as during welding or brazing operations.
1. Scope corresponding hardness values of 300 HV , 303 HB, or 31
10 kgf
HR ) or surface hardened threaded articles, fasteners, or rod.
c
1.1 This test method covers the determination of, on a
1.4 This test method shall be carried out after hydrogen
statistical basis, the probability of the existence of hydrogen
embrittlement relief heat treatment in accordance with the
embrittlement or degradation in:
requirements of Guide B 850. It may also be used for assessing
1.1.1 A batch of barrel electroplated, autocatalytic plated,
differences in processing solutions, conditions, and techniques.
phosphated, or chemically processed threaded articles or fas-
This test method has two main functions: first, when used with
teners and
a statistical sampling plan it can be used for lot acceptance or
1.1.2 A batch of rack plated threaded articles, fasteners, or
rejection, and second, it can be used as a control test to
rod.
determine the effectiveness of the various processing steps
1.2 Industrial practice for threaded articles, fasteners, and
including pre- and post-baking treatments to reduce the mobile
rod has evolved three graduated levels of test exposure to
hydrogen in the articles, fasteners, or rod. While this test
ensure reduced risk of hydrogen embrittlement (see Section 3).
method is capable of indicating those items that are embrittled
These levels have evolved from commercial applications
to the extent defined in Section 3, it does not guarantee
having varying levels of criticality. In essence, they represent
complete freedom from embrittlement.
the confidence level that is required. They also represent the
1.5 This test method does not relieve the processor from
time that finished goods are held before they can be shipped
imposing and monitoring suitable process control.
and used. This time equates to additional cost to the manufac-
1.6 This test method has been coordinated with ISO/DIS
turer that may of necessity be added to the cost of the finished
10587 and is technically equivalent. (Warning—Great care
goods.
should be taken when applying this test method. The heads of
1.3 This test method is applicable to threaded articles,
embrittled articles, fasteners, or rod may suddenly break off
fasteners, and rod made from steel with $1000 MPa (with
and become flying projectiles capable of causing blindness or
other serious injury. This hazard can occur as long as 200 h
This test method is under the jurisdiction of ASTM Committee B08 on Metallic
after the test has started. Hence, shields or other apparatus
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 on
should be provided to avoid such injury.)
Test Methods.
Current edition approved May 10, 2003. Published July 2003. Originally
approved in 1994. Last previous edition approved in 1994 as B 839 – 94.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
B 839 – 94 (2003)
NOTE 1—The use of inhibitors in acid pickling baths does not neces-
sarily guarantee avoidance of hydrogen embrittlement.
1.7 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 appro-
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
2. Referenced Documents
2.1 ASTM Standards:
B 602 Test Method for Attribute Sampling of Metallic and
Inorganic Coatings
B 697 Guide for Selection of Sampling Plans for Inspection
of Electrodeposited Metallic and Inorganic Coatings
F 436 Specification for Hardened Steel Washers
B 850 Guide for Post-Coating Treatments of Steel for Re-
ducing the Risk of Hydrogen Embrittlement
2.2 ISO Standards:
ISO/DIS 10587 Residual Embrittlement in Metallic Coated,
Externally Threaded Articles, Fasteners and Rod—
Inclined Wedge Method
ISO 4519 Electrodeposited Metallic Coatings and Related
Finishes—Sampling Procedures for Inspection by At-
tributes
2.3 Military Standard:
MIL-STD-1312 Fastener Test Methods
3. Terminology
3.1 Definitions—For the purposes of this test method the
following definitions apply:
3.1.1 batch—a distinct portion of items processed collec-
tively as a single group through the same identical treatment
steps at the same time on the same rack or in the same barrel.
FIG. 1 Example of 6° Wedge and Parallel Filler Plate
3.1.2 embrittled—where parts fail immediately or up to 48
h in test.
down into a number of batches for processing purposes and
3.1.2.1 Discussion—The degree to which parts within a
then reassembled into the same lot.
single plated batch or a given lot can be embrittled can vary
over a wide range. The degree of embrittlement is a function of
4. Summary of Test Method
the concentration of atomic hydrogen in the individual parts in
the batch or lot, measured in parts per million, and in particular
4.1 The threaded articles, fasteners, or rod are subjected to
that portion of the hydrogen that is mobile or free to migrate to
stress by tensioning with a mating nut after insertion through a
areas of high stress concentration.
clearance hole in a hardened rectangular wedge of steel; see
3.1.3 Grade 48 proof—where there are no failures after 48 Fig. 1. Additional hardened rectangular pieces of steel with
h of test.
parallel faces are provided as filler plates and are inserted so
3.1.4 Grade 96 proof—where there are no failures after 96 that the required length of the threaded article is placed under
h of test.
test. Other loading systems and fixtures are permissible as long
3.1.5 Grade 200 proof—where there are no failures after as the same load, angle, and exposure are created for the test.
200 h of test.
The upper surface of the wedge is ground at an angle to the
3.1.6 lot—a group of items processed through the same or lower surface. The mating nut is tensioned by any means
similar steps at the same time or over a contiguous time period
capable of measuring tensile load. The torque method de-
and from the same heat of material. The lot may be broken scribed in 6.4 is one such method. If the torque method of
tightening is used, the fasteners are torqued to the desired
value, held for the minimum specified hours, and then checked
to determine if the initial torque has been maintained. Follow-
Annual Book of ASTM Standards, Vol 02.05.
ing this they are examined for embrittlement failures. See
Annual Book of ASTM Standards, Vol 01.08.
Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
Section 9.
4th Floor, New York, NY 10036.
NOTE 2—Increasing the applied torque by a small percentage as a
Available from Standardization Documents Order Desk, Bldg. 4, Section D,
700 Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS. safety factor is not recommended.
B 839 – 94 (2003)
TABLE 1 Wedge Angle Selection (in degrees)
7.2 A minimum sample size of 30 pieces is necessary from
Articles with each embrittlement relief treated batch that exceeds 500 pieces
Articles with Unthreaded
Nominal Size of Unthreaded Lengths 2
plated as a single group.
Lengths Less than
Threaded Article Diameters
2 Diameters
and Longer
8. Procedure
2to6mm 6 6
1 1
⁄16 to ⁄4 in. 6 6
8.1 Test Item P
...
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