ASTM B849-02(2007)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:B849 −02(Reapproved 2007)
Standard Specification for
Pre-Treatments of Iron or Steel for Reducing Risk of
Hydrogen Embrittlement
This standard is issued under the fixed designation B849; 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.
INTRODUCTION
When atomic hydrogen enters steels and certain other metals, for example, aluminum and titanium
alloys, it can cause a loss of ductility, load carrying ability, or cracking (usually as submicroscopic
cracks) as well as 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 referred to frequently
as hydrogen-induced delayed brittle failure, hydrogen stress cracking, or hydrogen embrittlement.The
hydrogen can be introduced during cleaning, pickling, phosphating, electroplating, autocatalytic
processes, porcelain enameling, 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 the breakdown of unsuitable lubricants as well as
during welding or brazing operations. Parts that have been machined, ground, cold-formed, or
cold-straightened subsequent to hardening heat treatment are especially susceptible to hydrogen
embrittlement damage.
The results of research work indicate that the susceptibility of any material to hydrogen
embrittlement in a given test is related directly to its trap population. The time-temperature
relationship of the heat treatment is therefore dependent on the composition and structure of steels as
well as plating metals and plating procedures. Additionally, for most high-strength steels, the
effectiveness of the heat treatment falls off rapidly with a reduction of time and temperature.
1. Scope parts, such as the cleaning procedures prior to electroplating,
autocatalytic plating, porcelain enameling, and other chemical
1.1 This specification covers procedures for reducing the
coating operations.
susceptibility or degree of susceptibility to hydrogen embrittle-
ment or degradation that may arise in electroplating, autocata-
NOTE 1—1 MPa = 145.1 psi.
lytic plating, porcelain enameling, chemical conversion
1.3 This specification has been coordinated with ISO/DIS
coating, and phosphating and the associated pretreatment
9587 and is technically equivalent.
processes.Thisspecificationisapplicabletothosesteelswhose
1.4 The values stated in SI units are to be regarded as the
properties are not affected adversely by baking at 190 to 230°C
standard.
or higher (see 6.1.1).
1.2 The heat treatment procedures established herein have 2. Referenced Documents
been shown to be effective for reducing the susceptibility of
2.1 ASTM Standards:
steel parts of tensile strength 1000 MPa or greater that have
A919 Terminology Relating to Heat Treatment of Metals
been machined, ground, cold-formed, or cold-straightened
(Withdrawn 1999)
subsequent to heat treatment. This heat-treatment procedure is
B242 Guide for Preparation of High-Carbon Steel for Elec-
used prior to any operation capable of hydrogen charging the
troplating
1 2
This specification is under the jurisdiction of ASTM Committee B08 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Metallic and Inorganic Coatingsand is the direct responsibility of Subcommittee contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
B08.02 on Pre Treatment. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved June 1, 2007. Published June 2007. Originally the ASTM website.
approved in 1994. Last previous edition approved in 2002 as B849 – 02. DOI: The last approved version of this historical standard is referenced on
10.1520/B0849-02R07. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B849−02 (2007)
TABLE 1 Classes of Stress Relief Requirements for High- NOTE 2—The treatment class selected is based on experience with the
Strength Steels (See Sections 4 through 6 for Details on the
part, or similar parts, and the specific alloy used or with empirical test
Use of Table1) data. Because of factors such as alloy composition and structure, size,
mass, or design parameters, some parts may perform satisfactorily with no
Stress-Relief Heat-Treatment Classes for High-Strength Steels
stressrelieftreatment.ClassSR-0treatmentisthereforeprovidedforparts
Class
Steels of Tensile Strength Temperature,
Time, h that the purchaser wishes to exempt from treatment.
(R ), MPa °C
m
NOTE 3—The use of inhibitors in acid pickling baths is not necessarily
SR-0 not applicable
guaranteed to minimize hydrogen embrittlement.
SR-1 over 1800 200–230 min 24
NOTE 4—Class SR-1, the longest treatment, is the default when the
A
SR-2 over 1800 190–220 min 24
purchaserdoesnotspecifyaclass.Theelectroplater,supplier,orprocessor
SR-3 1401 to 1800 200–230 min 18
A is not normally in possession of the necessary information, such as design
SR-4 1450 to 1800 190–220 min 18
A
considerations, induced stresses from manufacturing operations, etc., that
SR-5 1034 or greater 177–205 min 3
must be considered when selecting the correct stress relief treatment. It is
SR-6 1000 to 1400 200–230 min 3
A
SR-
...