ASTM B849-02(2013)
(Specification)Standard Specification for Pre-Treatments of Iron or Steel for Reducing Risk of Hydrogen Embrittlement
Standard Specification for Pre-Treatments of Iron or Steel for Reducing Risk of Hydrogen Embrittlement
ABSTRACT
This specification covers the pre-treatment procedures of iron or steel for reducing the susceptibility or degree thereof to hydrogen embrittlement or degradation that may arise in electroplating, autocatalytic plating, porcelain enameling, chemical conversion coating, and phosphating.
SCOPE
1.1 This specification covers procedures for reducing the susceptibility or degree of susceptibility to hydrogen embrittlement or degradation that may arise in electroplating, autocatalytic plating, porcelain enameling, chemical conversion coating, and phosphating and the associated pretreatment processes. This specification is applicable to those steels whose properties are not affected adversely by baking at 190 to 230°C or higher (see 6.1.1).
1.2 The heat treatment procedures established herein have been shown to be effective for reducing the susceptibility of steel parts of tensile strength 1000 MPa or greater that have been machined, ground, cold-formed, or cold-straightened subsequent to heat treatment. This heat-treatment procedure is used prior to any operation capable of hydrogen charging the parts, such as the cleaning procedures prior to electroplating, autocatalytic plating, porcelain enameling, and other chemical coating operations. Note 1—1 MPa = 145.1 psi.
1.3 This specification has been coordinated with ISO/DIS 9587 and is technically equivalent.
1.4 The values stated in SI units are to be regarded as the standard.
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Designation:B849 −02 (Reapproved 2013)
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 Coatings and 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 May 1, 2013. Published May 2013. Originally the ASTM website.
approved in 1994. Last previous edition approved in 2007 as B849 – 02 (2007). The last approved version of this historical standard is referenced on
DOI: 10.1520/B0849-02R13. www.astm.org.
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B849−02 (2013)
TABLE 1 Classes of Stress Relief Requirements for High- part, or similar parts, and the specific alloy used or with empirical test
Strength Steels (See Sections 4 through 6 for Details on the
data. Because of factors such as alloy composition and structure, size,
Use of Table1) mass, or design parameters, some parts may perform satisfactorily with no
stressrelieftreatment.ClassSR-0treatmentisthereforeprovidedforparts
Stress-Relief Heat-Treatment Classes for High-Strength Steels
that the purchaser wishes to exempt from treatment.
Class
Steels of Tensile Strength Temperature,
Time, h NOTE 3—The use of inhibitors in acid pickling baths is not necessarily
(R ), MPa °C
m
guaranteed to minimize hydrogen embrittlement.
SR-0 not applicable
NOTE 4—Class SR-1, the longest treatment, is the default when the
SR-1 over 1800 200–230 min 24
purchaserdoesnotspecifyaclass.Theelectroplater,supplier,orprocessor
A
SR-2 over 1800 190–220 min 24
is not normally in possession of the necessary information, such as design
SR-3 1401 to 1800 200–230 min 18
A considerations, induced stresses from manufacturing operations, etc., that
SR-4 1450 to 1800 190–220 min 18
A
must be considered when selecting the correct stress relief treatment. It is
SR-5 1034 or greater 177–205 min 3
inthepurchasers’interestthattheirpartdesigner,manufacturingengineer,
SR-6 1000 to 1400 200–230 min 3
...
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