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GB/T 7216-2009 PDF in English


GB/T 7216-2009 (GB/T7216-2009, GBT 7216-2009, GBT7216-2009)
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GB/T 7216-2009: PDF in English (GBT 7216-2009)

GB/T 7216-2009
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.140.80
J 31
Replacing GB/T 7216-1987
Metallographic test for gray cast iron
(ISO 945-1.2008 Microstructure of cast irons -
Part 1. Graphite classification by visual analysis, MOD)
ISSUED ON. OCTOBER 30, 2009
IMPLEMENTED ON. APRIL 1, 2010
Issued by. General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration Committee.
Table of Contents
Foreword ... 3 
1 Scope ... 5 
2 Normative references ... 5 
3 Sample preparation ... 5 
4 Inspection items and evaluation figures ... 6 
5 Result representation ... 22 
6 Test report ... 22 
Appendix A ... 24 
Foreword
This Standard is modified on the basis of adopting ISO 945-1.2008
“Microstructure of cast irons - Part 1. Graphite classification by visual analysis”.
Compared with ISO 945-1.2008, the technical differences are as follows.
- Modify and adopt the I-type graphite of ISO 945-1.2008, and make editorial
changes in structure;
- Add F-type graphite distribution shape to replace C’-type in Appendix B of
ISO 945-1.2008;
- Add instructions on F-type in instructions on graphite distribution shapes;
- Add determination methods of pearlite number, carbide number,
phosphorus eutectic number, and eutectic number as well as corresponding
evaluation figures.
This Standard replaces GB/T 7216-1987 “Gray cast iron metallography”.
Compared with GB/T 7216-1987, main technical changes are as follows.
- Change the name of the standard to “Metallographic test for gray cast iron”;
- Delete item “Name” in Table 2 of previous standard; add item “Graphite’s
actual length”; the graphite’s length picture is replaced by I-type graphite’s
length picture of ISO 945-1.2008;
- Add result representation;
- Add test report;
- Replace C-type graphite’s picture;
- Delete inspection item “pearlite spacing”;
- Delete “matrix structure characteristics”;
- Delete “carbide distribution shape”;
- Delete “phosphide eutectic distribution shape”;
Metallographic test for gray cast iron
1 Scope
This Standard specifies the evaluation method of gray cast iron microstructure
under optical microscope.
This Standard makes provisions in pearlite number, carbide number,
phosphorus eutectic number, and eutectic number. It also lists corresponding
evaluation figures.
This Standard is applicable to the microstructure that is used to evaluate
ordinary and low-alloy gray cast irons.
2 Normative references
The following standards contain the provisions which, through reference in this
Standard, constitute the provisions of this Standard. For dated references, the
subsequent amendments (excluding corrections) or revisions do not apply to
this Standard. However, the parties who enter into agreement based on this
Standard are encouraged to investigate whether the latest versions of these
documents are applicable. For undated reference documents, the latest
versions apply to this Standard.
GB/T 9439 Grey Iron Castings
GB/T 13298 Metal - Inspection Method of Microstructure
3 Sample preparation
3.1 Metallographic sample shall be extracted on the test block or casting that is
casted and heat-treated in same furnace with the casting, according to the
provisions in GB/T 9439.
3.2 Preparation of metallographic sample shall be conducted according to the
provisions in GB/T 13298. During the process of metallographic sample
extracting and preparing, it shall prevent structural changes, graphite flake or
graphite trailing. The sample surface shall be smooth. Huge scratches are not
allowed.
4 Inspection items and evaluation figures
4.1 Graphite distribution shape
4.1.1 Inspect graphite distribution shape under polishing state. Firstly observe
the whole plane under inspection. Evaluate it according to most of graphite field
distribution shapes and compare with corresponding evaluation figures.
Magnification is 100 times.
4.1.2 If there are different shapes of graphite in a same sample, it shall observe
and estimate the percentage of each shape of graphite and successively
indicate it in report.
4.1.3 There are 6 graphite distribution shapes, as shown in Table 1.
Table 1
Graphite
type Instruction
Figure
No.
A Flake graphite is evenly and non-directionally distributed. 1
B Flake and small curly graphite gather and are distributed like a daisy. 2
C New-born, huge and straight flake graphite. 3a
D Small and curly flake graphite is non-directionally distributed in dendrite. 4
E Flake graphite is directionally distributed in secondary branch of dendrite. 5
F New-born star (or spider-like) graphite. 6c
a If there are only huge and straight flake graphite, it shall be C-type graphite.
b If it is only directionally distributed in secondary branch of dendrite, it shall be E-type
graphite.
c If there are only new-born star (or spider-like) graphite, it shall be F-type graphite.
Appendix A
(Informative)
Phosphorus eutectic type
A.1 According to its composition, phosphorus eutectic can be divided into four
types. binary phosphorus eutectic, ternary phosphorus eutectic, binary
phosphorus eutectic carbide composite and ternary phosphorus eutectic
carbide composite.
A.2 The sample in polishing state is eroded by 2%~5% nital and observed in
500 times of magnification. Phosphorus eutectic’s types and topographies are
shown in Table A.1, Figure A.1 ~ A.4.
Table A.1 Phosphorus eutectic type
Type Structure and characteristics Figure No.
Binary phosphorus
eutectic
Granules of austenite grain decomposition
product are evenly distributed on iron
phosphide.
A.1
Ternary phosphorus
eutectic
Granules of austenite grain decomposition
product, granular and strip carbonizations
are evenly distributed on iron phosphide.
A.2
Binary phosphorus
eutectic carbide
composite
Binary phosphorus eutectic and huge
blocky carbides. A.3
Ternary phosphorus
eutectic carbide
composite
Ternary phosphorus eutectic and huge
blocky carbides. A.4
......
 
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.