ASTM B850-98
(Specification)Standard Guide for Post-Coating Treatments of Steel for Reducing the Risk of Hydrogen Embrittlement
Standard Guide for Post-Coating Treatments of Steel for Reducing the 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 the finishing processes.
1.2 The heat treatment procedures established herein have been shown to be effective for reducing susceptibility to hydrogen embrittlement. This heat-treatment procedure is used after plating operations but prior to any secondary conversion coating operation.
1.3 This specification has been coordinated with ISO/DIS 9588 and is technically equivalent. Note 1-The heat treatment does not guarantee complete freedom from the adverse effects of hydrogen degradation.
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Designation: B 850 – 98
Standard Guide for
Post-Coating Treatments of Steel for Reducing Risk of
Hydrogen Embrittlement
This standard is issued under the fixed designation B 850; 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 steel, 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.
1. Scope ISO 2080 Electroplating and Related Processes—
Vocabulary
1.1 This guide covers procedures for reducing the suscep-
ISO DIS 9588 Post-Coating Treatments of Iron or Steel for
tibility in some steels to hydrogen embrittlement or degrada-
Reducing the Risk of Hydrogen Embrittlement
tion that may arise in the finishing processes.
2.3 Federal Standard:
1.2 The heat treatment procedures established herein may
QQ-C-320 Chromium Plating (Electrodeposited)
be effective for reducing susceptibility to hydrogen embrittle-
ment. This heat-treatment procedure shall be used after plating
3. Terminology
operations but prior to any secondary conversion coating
3.1 Definitions—Many of the terms used in this guide can
operation.
be found in Terminology B 374, A 919, or ISO 2080.
1.3 This guide has been coordinated with ISO/DIS 9588 and
is technically equivalent.
4. Requirements
NOTE 1—The heat treatment does not guarantee complete freedom
4.1 Heat treatment may be performed on coated metals to
from the adverse effects of hydrogen degradation.
reduce the risk of hydrogen embrittlement. The duration of
heat treatment in all cases shall commence from the time at
2. Referenced Documents
which the whole of each part attains the specified temperature.
2.1 ASTM Standards:
4.2 Parts made from steel with actual tensile strengths
A 919 Terminology Relating to Heat Treatment of Metals
$1000 MPa (with corresponding hardness values of 300
B 374 Terminology Relating to Electroplating
HV , 303 HB, or 31 HR ) and surface-hardened parts may
10kgf C
B 851 Specification for Automated Controlled Shot Peening
require heat treatment unless Class ER-0 is specified. Prepara-
of Metallic Articles Prior to Nickel, Autocatalytic Nickel,
tion involving cathodic treatments in alkaline or acid solutions
or Chromium Plating, or as Final Finish
shall be avoided. Additionally, the selection of electroplating
2.2 ISO Standards:
solutions with high cathodic efficiencies is recommended for
steel components with tensile strengths above 1400 MPa (with
corresponding hardness values of 425 HV , 401 HB, or 43
10kgf
HR ).
This specification is under the jurisdiction of ASTM Committee B-8 on
C
Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee
B08.02 on Substrate Preparation.
Current edition approved Dec. 10, 1998. Published March 1999. Originally Available from American National Standards Institute, 11 W. 42nd St., 13th
published as B 850–94. Last previous edition B 850–94. Floor, New York, NY 10036.
2 5
Annual Book of ASTM Standards, Vol 01.02. Available from DODSSP, Standardization Documents Order Desk, Bldg. 4
Annual Book of ASTM Standards, Vol 02.05. Section D, 700 Robbins Ave., Philadelphia, PA 19111.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
B850–98
4.3 Table 1 provides a list of embrittlement-relief heat- B 851, heat treatment conditions may be selected on the basis
treatment classes from which the purchaser may specify the of actual tensile strength. When only the minimum tensile
treatment required to the electroplater, supplier, or processor on strength is specified, or if the tensile strength is not known, the
the part drawing or purchase order. heat treatment condition may be selected by relating known or
measured hardness values to equivalent tensile strengths. It is
NOTE 2—The treatment class selected is based on experience with the
recommended that the tensile strength be supplied by the
part, or similar parts, and the specific alloy used or with empirical test
purchaser.
data. Because of factors such as alloy composition and structure, type of
coating, coating thickness, size, mass, or design parameters, some parts 5.2 Steels that have been wholly or partly surface hardened
may perform satisfactorily with no embrittlement-relief treatment. Class
may be considered as be
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