GB/T 16746-2018 PDF English (GB/T 16746-1997: Older version)
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Zinc Alloy Castings
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GB/T 16746-2018: PDF in English (GBT 16746-2018) GB/T 16746-2018
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.150.60
J 31
Replacing GB/T 16746-1997
Zinc Alloy Castings
ISSUED ON. JULY 13, 2018
IMPLEMENTED ON. AUGUST 1, 2018
Issued by. State Administration for Market Regulation;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative References ... 5
3 Casting Classification ... 5
4 Technical Requirements ... 6
5 Test Methods ... 10
6 Inspection Rules ... 11
7 Marking, Packaging, Transportation and Storage ... 14
Foreword
This Standard is drafted in accordance with stipulations in GB/T 1.1-2009.
This Standard serves as a replacement of GB/T 16746-1997 Zinc Alloy Castings. In
comparison with GB/T 16746-1997, there are several main technical changes as
follows.
---Casting classification is modified (please refer to Chapter 3; Chapter 3 in
Version 1997);
---The requirement of chemical composition is added (please refer to 4.1);
---The mechanical properties of casting body are added (please refer to Table 2 in
4.2.2);
---The appearance quality of castings is modified (please refer to 4.4; 4.1 in
Version 1997);
---The internal quality of castings is modified (please refer to 4.5; 4.2 in Version
1997);
---The welding repair of castings is modified (please refer to 4.6; Chapter 6 in
Version 1997);
---The status of supply is added (please refer to 4.7);
---Test methods are added (please refer to Chapter 5);
---Inspection rules are modified (please refer to Chapter 6; Chapter 5 in Version
1997).
This Standard was proposed by and shall be under the jurisdiction of National
Technical Committee (54) on Casting of Standardization Administration of China
(SAC/TC 54).
The responsible drafting organizations of this Standard. Ningbo Yinzhou Yunying
Machinery Manufacturing Co., Ltd.
The participating drafting organizations of this Standard. Chuzhou Jinnuo Industrial
Co., Ltd., Huoshan Zhongfu Electromechanical Science and Technology Co., Ltd.,
Guizhou Metallurgical and Chemical Research Institute, Dongguan Shijie Huafeng
Metal Co., Ltd., National Construction Hardware Product Quality Supervision and
Inspection Center (Guangdong), Shenzhen Lingwei Science and Technology Co., Ltd.,
Guizhou Academy of Sciences, Ningbo University of Technology.
The main drafters of this Standard. Zhu Fangcheng, Dai Jiaoyan, Ma Zhengsong, Du
Zinc Alloy Castings
1 Scope
This Standard specifies the classification, technical requirements, test methods,
inspection rules, marking, packaging, transportation and storage of zinc alloy castings.
This Standard is applicable to zinc alloy castings that are manufactured with sand
casting and special casting process (excluding pressure casting).
2 Normative References
The following documents are indispensable to the application of this Standard. In terms
of references with a specified date, only versions with a specified date are applicable
to this Standard. The latest version (including all the modifications) of references
without a specified date is also applicable to this Standard.
GB/T 228.1-2010 Metallic Materials - Tensile Testing - Part 1. Method of Test at
Room Temperature
GB/T 1175 Casting Zinc Alloys
GB/T 15056 Casting Surface Roughness - Appraising Method
HB 6578 Reference Radiographic Film for Aluminum Magnesium Alloy Castings
Examination (negative film unavailable)
JB/T 7946.3 Metallograph of Cast Aluminum Alloys - Part 3. Cast Aluminum Alloys
Pinhole
3 Casting Classification
Please refer to Table 1 for the classification of castings.
Table 1 -- Castings Classification
Casting
Classification Definition
Important castings that bear heavy load and request complicated working
conditions; important castings that are used in critical parts and will endanger
the safe operation of the whole machine if the castings are damaged
II Castings that bear medium load and that are used in important parts; casting damage will affect the normal operation of certain parts and lead to accidents
III Castings that bear slight load or bear no load; castings that are used in
4.3 Dimensional Tolerances
4.3.1 The dimensions and dimensional tolerances of castings shall comply with the
requirements on the drawings.
4.3.2 The dimensional tolerances of castings shall not include any dimensional
increase or decrease caused by draft angle. However, the minimum limit dimension of
castings shall be guaranteed.
4.4 Appearance Quality
4.4.1 Excessive material defects (such as sand inclusion and burr) on the surface of
castings shall eliminated. Sandblasting can be conducted on the surface of castings.
Parts that serve as a benchmark on castings shall be flat and smooth.
4.4.2 Cold partition, crack, penetrating defects and severe defective defects (such as
defective casting, unthorough casting and mechanical damage, etc.) are not allowed
to exist on castings.
4.4.3 The roughness of the non-processing surface of castings shall be indicated by
the demand side on the drawings.
4.4.4 On the to-be-processed surface of castings, any defects that can be eliminated
through processing are allowed to exist.
4.4.5 On the non-processing surface of metal castings, traces of casting partition,
mandrel and exhaust plug are allowed to exist. However, the protrusion area shall not
exceed 1 mm over the surface, or the sagging area shall not be 0.5 mm lower than the
surface.
4.4.6 After cleaning up the non-processing surface and processed surface of sand
castings and metal castings, the following holes are allowed to exist.
a) The maximum diameter of a single hole shall not be more than 3 mm; the depth
shall not exceed 1/3 of wall thickness; on the edges of installation, the depth
shall not exceed 1/4 of wall thickness, and not more than 1.5 mm. On the
reverse side of the same cross section with the above-mentioned defects,
similar defects are not allowed on the symmetrical parts. Single holes whose
maximum diameter is less than 1 mm on the non-processing surface, and
single holes whose maximum diameter is less than 0.5 mm on the processed
surface shall not be included.
b) In terms of bunching holes on Grade-I and Grade-II castings, the maximum
diameter shall be not more than 1.5 mm, and the depth shall not exceed 1/3 of
wall thickness and not more than 1 mm. In terms of bunching holes on Grade-
III castings, the maximum diameter shall be not more than 2 mm, and the depth
shall not exceed 1/3 of wall thickness and not more than 1.5 mm.
The method of mechanical properties test shall comply with the stipulation in GB/T
228.1-2010.
5.3 Tolerances of Geometric Dimension
Geometric dimension shall be measured with exclusive measuring instrument or
general measuring instrument.
5.4 Appearance Quality
5.4.1 In accordance with the requirement in 4.4.1, clean up and flatten castings, then,
conduct tests on the shape, surface roughness and surface defects, etc. The
appearance quality of castings shall be tested through visual inspection (or a less than
10 times magnifier) and appropriate measuring tool, instrument or test method.
5.4.2 The degree of pinhole of the processed surface of castings shall be assessed in
accordance with the stipulation in JB/T 7946.3.
5.4.3 The degree of roughness of the non-processed surface of castings shall be
assessed in accordance with the stipulation in GB/T 15056.
5.5 Internal Quality
5.5.1 The grading of internal defects, such as pinhole, air hole and porosity, shall
comply with the stipulation in HB 6578.
5.5.2 The internal quality of castings shall receive X-radiographic inspection and
industrial CT inspection in accordance with the requirement on the drawings.
5.6 Welding Repair
5.6.1 After welding repair, visually inspect (or with the help of a magnifier) the quality
of surface welding. The area of such inspection shall be not less than 2 times of the
welding repair area.
5.6.2 After welding repair, conduct nondestructive testing in the welding area. Defects
can be determined in accordance with HB 6578. The area of such testing shall be not
less than 2 times of the welding repair area. All the welding repair areas of Grade-I
castings shall be tested; in terms of Grade-II castings, conduct sampling inspection
under a certain proportion in accordance with the demand side’s request.
6 Inspection Rules
6.1 Group Batch
The same type of products that are manufactured through the same smelting furnace
and the same thermal treatment furnace shall be deemed as one batch.
mechanical properties. If all of the test pieces are qualified in the test with a doubled
sampling size, this furnace (batch) of castings are qualified in mechanical properties,
otherwise, they are unqualified.
6.4.9 When there is a requirement towards hardness, comply with the stipulation in
GB/T 1175. Conduct sampling inspection from the same batch of castings. If they are
unqualified, take a doubled sampling size. If all of the test pieces are qualified in the
test with a doubled sampling size, this furnace of castings are qualified in hardness,
otherwise, they are unqualified.
6.5 Appearance Quality
The appearance quality of castings shall receive 100% visual inspection one by one.
6.6 Internal Quality
6.6.1 Conduct X-radiographic inspection of internal defects of castings in accordance
with the stipulation on the drawings. When X-radiographic sampling inspection is
conducted under a certain proportion, calculate the number of detected flaws in
accordance with the number of castings that are casted under each smelting furnace.
6.6.2 Conduct sampling inspection as requested. When test pieces fail in the X-
radiographic sampling inspection, take a double quantity of test pieces or castings for
a re-inspection. If they are still unqualified, inspect all the castings one by one.
7 Marking, Packaging, Transportation and Storage
7.1 Marking
7.1.1 Mark alloy code and smelting furnace number in spots that are specified on the
drawings. The marks shall be clearly visible and traceable.
7.1.2 Castings shall be attached with a quality certificate, which shall include the
following content.
a) Name of the supply side;
b) Number and title of the Standard;
c) Casting name and ally nameplate (code);
d) Result of chemical composition analysis, mechanical properties test and other
test items;
e) Furnace batch number;
f) Quantity (number) and batch number of casting;
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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