ASTM B849-94
(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
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.
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: B 849 – 94
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Specification for
Pre-Treatments of Iron or Steel for Reducing Risk of
Hydrogen Embrittlement
This standard is issued under the fixed designation B 849; 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 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 autocatalytic plating, porcelain enameling, and other chemical
coating operations.
1.1 This specification covers procedures for reducing the
susceptibility or degree of susceptibility to hydrogen embrittle-
NOTE 1—1 MPa 5 145.1 psi.
ment or degradation that may arise in electroplating, autocata-
1.3 This specification has been coordinated with ISO/DIS
lytic plating, porcelain enameling, chemical conversion coat-
9587 and is technically equivalent.
ing, and phosphating and the associated pretreatment
1.4 The values stated in SI units are to be regarded as the
processes. This specification is applicable to those steels whose
standard.
properties are not affected adversely by baking at 190 to 230°C
or higher (see 6.1.1).
2. Referenced Documents
1.2 The heat treatment procedures established herein have
2.1 ASTM Standards:
been shown to be effective for reducing the susceptibility of
A 919 Terminology Relating to Heat Treatment of Metals
steel parts of tensile strength 1000 MPa or greater that have
B 242 Practice for Preparation of High-Carbon Steel for
been machined, ground, cold-formed, or cold-straightened
Electroplating
subsequent to heat treatment. This heat-treatment procedure is
B 322 Practice for Cleaning Metals Prior to Electroplating
used prior to any operation capable of hydrogen charging the
B 374 Terminology Relating to Electroplating
parts, such as the cleaning procedures prior to electroplating,
B 851 Specification for Automated Controlled Shot Peening
of Metallic Articles Prior to Nickel, Autocatalytic Nickel,
or Chromium Plating, or as Final Finish
This specification is under the jurisdiction of ASTM Committee B-8 on
Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee
B08.02 on Substrate Preparation. Annual Book of ASTM Standards, Vol 01.02.
Current edition approved March 15, 1994. Published May 1994. Annual Book of ASTM Standards, Vol 02.05.
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
B 849
TABLE 1 Classes of Stress Relief Requirements for High-
2.2 ISO Standards:
Strength Steels (See Sections 4 through 6 for Details on the
ISO 2080 Electroplating and Related Processes—
Use of Table 1)
Vocabulary
Stress-Relief Heat-Treatment Classes for High-Strength Steels
ISO/DIS 9587 Pre-Treatments of Iron or Steel for Reducing
Class
Steels of Tensile Strength Temperature,
the Risk of Hydrogen Embrittlement
Time, h
(R ), MPa °C
m
2.3 Federal Standard:
SR-0 not applicable
QQ-C-320 Chromium Plating (Electrodeposited)
SR-1 over 1800 200–230 min 24
A
SR-2 over 1800 190–220 min 24
3. Terminology SR-3 1401 to 1800 200–230 min 18
A
SR-4 1450 to 1800 190–220 min 18
3.1 Definitions—Many of the terms used in this specifica- A
SR-5 1034 or greater 177–205 min 3
tion can be found in Terminology B 374, A 919, or ISO 2080. SR-6 1000 to 1400 200–230 min 3
A
SR-7 1050 to 1450 190–220 min 1
SR-8 surface-hardened parts # 1400 130–160 min 8
4. Requirements
A
Classes SR-2, SR-4, SR-5, and SR-7 are traditional treatments used in
4.1 Heat
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.