GB/T 11379-2008 English PDF (GBT11379-2008)

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GB/T 11379-2008: Metallic coatings -- Electroplated coatings of chromium for engineering purposes
GB/T 11379-2008
GB
NATIONAL STANDARD OF THE
PEOPLE'S REPUBLIC OF CHINA
ICS 25.220.40
A 29
GB/T 11379-2008 / ISO 6158.2004
Replacing GB/T 11379-1989
Metallic coatings - Electroplated coatings of chromium for
engineering purposes
(ISO 6158.2004, IDT)
ISSUED ON. JUNE 19, 2008
IMPLEMENTED ON. JANUARY 1, 2009
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of PRC;
Standardization Administration of PRC.
Table of Contents
Foreword... 3
Introduction... 5
1 Scope... 6
2 Normative references... 6
3 Terms and definitions... 7
4 Information to be supplied to the electroplater... 8
5 Designation... 9
6 Requirements... 12
7 Sampling... 15
Appendix A (informative) Typical thickness of chromium specified in engineering
applications... 16
Appendix B (informative) Thickness test methods for electroplated chromium and other
metallic coatings... 17
Appendix C (normative) Determination of cracks and pores in chromium coatings.. 18
References... 20
Foreword
This standard is identical to ISO 6158.2004 Metallic coatings - Electrodeposited
coatings of chromium for engineering purposes (English version).
This standard was drafted based on the translation of ISO 6158.2004.
For ease of use, this standard has made the following editorial changes.
-- The foreword of the international standard is deleted and the foreword of the
Chinese standard is added;
-- The term "this International Standard" is replaced by "this Standard";
-- The Chinese national standards corresponding to international standards are cited.
This standard replaces GB/T 11379-1989 Metallic coatings - Electroplated coatings of
chromium for engineering purposes. The main changes compared with GB/T 11379-
1989 are as follows.
-- The "Introduction" and "Designation" are added;
-- The requirements for chromium electroplating coatings are modified;
-- The characteristics, application examples and related instructions of chromium
electroplated coatings for engineering purposes are deleted;
-- The typical thicknesses of chromium electroplated coatings for engineering use
are added;
-- The measuring method of shot peening intensity is deleted.
Appendix C of this standard is a normative appendix, and Appendix A and Appendix B
are both informative appendices.
This standard was proposed by China Machinery Industry Federation.
This standard is under the jurisdiction of the National Technical Committee on Metallic
and Non-metallic Coatings of Standardization Administration of China (SAC/TC57).
Drafting organization of this standard. Wuhan Research Institute of Materials
Protection, Guangdong Dazhi Chemical Technology Co., Ltd., Nanjing Jingjing
Surface Technology Co., Ltd., Hangzhou Paradise Umbrella Group Co., Ltd.
Main drafters of this standard. Zhang Dezhong, Mao Zuguo, Cai Zhihua, Jia Jianxin,
Zhang Shengda, Wang Qiwei, He Jie.
Metallic coatings - Electroplated coatings of chromium for
engineering purposes
1 Scope
This Standard specifies requirements for electroplated coatings of chromium, with or
without undercoats, on ferrous and non-ferrous metals for engineering purposes. The
coating designation provides a means of specifying the thickness of chromium
appropriate for typical engineering applications.
2 Normative references
The provisions in the following documents become the provisions of this standard
through reference in this standard. For the dated references, the subsequent amendments
(excluding corrections) or revisions do not apply to this standard, however, parties who
reach an agreement based on this standard are encouraged to study if the latest versions
of these documents are applicable. For undated references, the latest editions of the
referenced documents apply to this standard.
GB/T 3138 Terminology for metallic coating, chemical treatment and related
process (GB/T 3138-1995, neq ISO 2079.1981)
GB/T4955 Metallic coatings - Measurement of coating thickness - Coulometric
method by anodic dissolution (GB/T 4955-2005, ISO 2177.2003, IDT)
GB/T 4956 Non-magnetic coatings on magnetic substrates - Measurement of
coating thickness - Magnetic method (GB/T 4956-2003, ISO 2178.1982, IDT)
GB/T 5270 Metallic coatings on metallic substrates - Electrodeposited and
chemically deposited coatings - Review of methods available for testing adhesion
(GB/T 5270-2005, ISO 2819.1980, IDT)
GB/T 6462 Metallic and oxide coatings - Measurement of coating thickness -
Microscopical method (GB/T 6462-2005, ISO 1463.2003, IDT)
GB/T 6463 Metallic and other inorganic coatings - Review of methods of
measurement of thickness (GB/T 6463-2005, ISO 3882.2003, IDT)
GB/T 9790 Metallic and related coatings - Vickers and Knoop microhardness tests
(GB/T 9790-1988, neq ISO 4516.1980)
6.7 Porosity
Electroplated ferrous articles (or special test specimens) shall be subjected to the
ferroxyl test described in GB/T 17721, or to an alternate porosity test designated by the
purchaser. The part fails if more than the number of pores per part or per unit area
exceeds that agreed between the purchaser and the electroplater.
When porous, cracked or other types of discontinuous chromium coatings are specified,
the determination of the number of pores and cracks in the chromium shall be carried
out by visual examination using an optical microscope of suitable magnification, or by
the method given in Appendix C, when applicable [see 4.1 h)].
NOTE. The method given in Appendix C may not be applicable to thick chromium coatings where cracks
or pores do not extend to the basis metal or to a nickel undercoat.
6.8 Stress relief heat treatment prior to coating
When specified by the purchaser, steel parts that have an ultimate tensile strength equal
to or greater than 1000 MPa (31 HRC) and that contain tensile stresses caused by
machining, grinding, straightening or cold-forming operations shall be given a stress
relief heat treatment prior to cleaning and metal deposition. The procedures and classes
for stress relief heat treatment shall be as specified by the purchaser or the purchaser
may specify appropriate procedures and classes from GB/T 19349 [see 4.1 i)].
Steels with oxide or scale shall be cleaned before the application of the coatings. For
high-strength steels, non-electrolytic alkaline and anodic alkaline cleaners, as well as
mechanical cleaning procedures, are preferred to avoid the risk of producing hydrogen
embrittlement during cleaning operations. The possibility of overheating shall be
considered in the case of mechanical cleaning of high-strength steels (tensile strength >
1400 MPa).
6.9 Hydrogen embrittlement relief heat treatment
Steel parts having an ultimate tensile strength ≥ 1000 MPa (31 HRC), as well as surface
hardened parts, shall receive hydrogen embrittlement relief heat treatment according to
the procedures and classes of GB/T 19350 or as specified by the purchaser [see 4.1 j)].
The effectiveness of the embrittlement relief treatment may be determined by a test
method specified by the purchaser or by test methods described in standards, e.g., GB/T
6462 and ISO 15724.
6.10 Peening of metal parts
If peening prior to or after electroplating is specified by the purchaser, it shall be
performed in accordance with GB/T 20015.The method of measuring shot peening
intensity is also described in that Standard [see 4.2 d)].