GB/T 2972-2016 PDF in English

GB/T 2972-2016 (GB/T2972-2016, GBT 2972-2016, GBT2972-2016)
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GB/T2972-2016 (GBT2972-2016): PDF in English

GB/T 2972-2016
H 25
Replacing GB/T 2972-1991
Test method for uniformity of zinc coating on
zinc-coated steel wire by the copper sulfate dip
(ISO 7989-2.2007 Steel wire and wire products –
Non-ferrous metallic coatings on steel wire - Part 2. Zinc or zinc-alloy coating, NEQ)
ISSUED ON. JUNE 14, 2017
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine of the People’s Republic of China;
Standardization Administration of the People's Republic of China.
3. No action is required - Full-copy of this standard will be automatically &
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Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative references ... 5 
3 Test Principle ... 5 
4 Sample Preparation ... 6 
5 Reagent Preparation ... 6 
6 Test Procedure ... 7 
7 Principle for accessing result ... 7 
Annex A (Informative) Determination of zinc in copper sulfate impregnation
solution -- Titration ... 9 
This Standard is drafted as per provisions specified in GB/T 1.1-2009.
This Standard replaces GB/T 2972-1991 “Zinc-coated steel wire - Test method
for uniformity of zinc coating on wire by the copper sulphate dip”. Compared
with GB/T 2972-1991, this Standard makes significant changes in the respect
of the following technical contents.
-- for application scope, add “Zn-Al alloy coated steel wire can refer to this
-- add normative references;
-- modify the sample preparation requirements; sample length is modified to
-- modify reagent preparation requirements; modify crystal of copper
sulphate to analytical pure; modify amount to 314g/L and temperature to
20°C ± 2°C; heating during dissolution is not allowed;
-- delete copper hydroxide and copper carbonate in the neutralization
-- delete specific gravity requirements of test solution;
-- add Annex A “Test method of zinc content in copper sulfate test solution”.
This Standard is drafted by adopting the re-drafting method and referencing to
ISO 7989-2.2007 “Steel wire and wire products - Non-ferrous metallic coatings
on steel wire - Part 2. Zinc or zinc-alloy coating”. This Standard is not equivalent
to ISO 7989-2.2007.
This Standard was proposed by China Iron and Steel Industry Association.
This Standard shall be under the jurisdiction of National Technical Committee
for standardization of steel (SAC/TC 183).
Drafting organizations of this Standard. National Quality Supervision and
Inspection Center for Wire Rope Products; China Metallurgical Information and
Standardization Institute; Institute of Quality and Quantity Supervision Center
of Yuhang District of Hangzhou.
The main drafters of this Standard Chen Jianhao, Yang Jinyan, Liu Aihua, Wang
Lingjun, Ren Cuiying, Liang Pengshan.
Test method for uniformity of zinc coating on
zinc-coated steel wire by the copper sulfate dip
1 Scope
This Standard specifies the testing principle, sample preparation, reagent
preparation, testing procedure and judgment principle for test method for
uniformity of zinc coating on zinc-coated steel wire by the copper sulfate dip.
This Standard is applicable to the uniformity test of zinc coating of hot-dip zinc-
coated steel wire. For zinc-aluminum alloy coated steel wire and zinc-
electroplated steel wire, it can also refer to this Standard.
2 Normative references
The provisions of the following documents, through reference of this document,
constitute the provisions of this document. For dated documents, only the dated
editions are applicable to this document. For undated documents, the latest
editions (including all amendments) are applicable to this document.
GB/T 603 Chemical reagent - Preparations of reagent solutions for use in
test methods
GB/T 665 Chemical reagent - Copper (II) sulfate pentahydrate
GB/T 674 Chemical reagent - Copper (II) oxide powder
3 Test Principle
During the pre-determined time, the zinc-coated steel wire sample is dipped
into the copper sulphate solution once or several times, for carrying out the
replacement reaction; the zinc coating is gradually dissolved. And finally,
defects are revealed on the surface; judge the uniformity of the zinc coating.
Note. This test is to reflect that the coating thickness may exist non-uniformity, therefore, even
if the coating on unit area complies with relevant requirements, defects on coating
surface can also be revealed.
6 Test Procedure
6.1 The samples after cleaning shall be immersed vertically in the center of the
stationary test solution; the test solution must not be stirred. The samples must
not be in contact with each other and shall not be in contact with the vessel wall.
After immersion as per the time specified in steel wire product standard (30s or
60s), take out the sample smoothly; wash it in water immediately; use absorbent
cotton, cloth or brush to remove the copper and its compounds that are attached
to, but not yet firmly adhered, the surface of the zinc coating. During the test,
the temperature is maintained at 20°C ± 2°C; record the actual temperature.
6.2 Repeat the immersion test in accordance with the above procedure, until
metal copper which are firmly adhered to the surface of the sample is first-time
appeared, or until reaching the immersion times as specified in wire product
standard. After the last immersion test, the sample shall be washed under
running water; use absorbent cotton and clean-soft cloth to clean-dry.
6.3 After multiple tests, when concentration of the dissolved zinc in solution
exceeds 5g/L, the solution shall be replaced. The zinc content in copper sulfate
test solution can be determined by the method specified in Appendix A. In order
to save time, under the premise of guaranteeing no mutual contact, maximum
6 samples can be tested at the same time.
6.4 Judgment of test end.
a) When bright and firmly adhered copper precipitated on the base steel of
the sample, it is the test end.
b) The test end is not reached in following cases.
1) There is bright and firmly adhered copper precipitated, however, the
area is less than 5mm2;
2) The precipitated copper can be removed with a blunt device (such as a
knife blade) and zinc coating is appeared under copper (In order to
judge if there is zinc coating under copper, it may drop, at that position,
a few drops of 5% dilute hydrochloric acid that contains 0.16% antimony
trichloride. If there is zinc coating, lively hydrogen may be generated);
3) Copper is precipitated 25mm away from the end of sample.
7 Principle for accessing result
Carry out the operation of Chapter 6. The products are deemed as qualified if