GB/T 25747-2022 English PDF (GBT25747-2022)

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GB/T 25747-2022: Magnesium alloy die castings
GB/T 25747-2022
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 77.120.20
CCS J 31
Replacing GB/T 25747-2010
Magnesium alloy die castings
ISSUED ON: MARCH 09, 2022
IMPLEMENTED ON: OCTOBER 01, 2022
Issued by: State Administration for Market Regulation;
Standardization Administration of PRC.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Terms and definitions ... 6
4 Technical requirements ... 6
5 Test methods ... 10
6 Inspection rules ... 11
7 Marking, packaging, transportation, storage ... 13
Appendix A (Informative) Mechanical properties of die casting magnesium alloy
specimens ... 15
Appendix B (Informative) Additional amount when line size is affected by parting
surface ... 16
Appendix C (Informative) Additional amount when the line size is affected by the
movable part of the mold ... 17
Appendix D (Informative) Shape and position tolerances of die castings ... 18
Appendix E (Normative) Internal defects of die castings ... 20
Magnesium alloy die castings
1 Scope
This document specifies the technical requirements, test methods, inspection rules,
marking, packaging, transportation, storage of magnesium alloy die castings.
This document applies to magnesium alloy die castings (hereinafter referred to as "die
castings").
2 Normative references
The contents of the following documents constitute essential provisions of this
document through normative references in the text. Among them, for dated references,
only the version corresponding to the date applies to this document; for undated
references, the latest version (including all amendments) is applicable to this document.
GB/T 228.1 Metallic materials - Tensile testing - Part 1: Method of test at room
temperature
GB/T 231.1 Metallic materials - Brinell hardness test - Part 1: Test method
GB/T 1182 Geometrical Product Specifications (GPS) - Geometrical tolerancing -
Tolerances of form orientation location and run-out
GB/T 1958 Geometrical product specifications (GPS) - Geometrical tolerance -
Verification prescription
GB/T 2828.1 Sampling procedures for inspection by attributes - Part 1: Sampling
schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection
GB/T 2829 Sampling procedures and tables for periodic inspection by attributes
(Apply to inspection of process stability)
GB/T 3177 Geometrical product specifications (GPS) - Inspection of plain
workpiece sizes
GB/T 5611 Foundry terminology
GB/T 6414-2017 Castings - Dimensional tolerances and geometrical tolerances and
machining allowances
GB/T 11351-2017 Mass tolerances of casting
4.2.3 If there is no special provision, the mechanical properties shall not be used as the
basis for acceptance.
4.3 Dimensions
4.3.1 The geometry and size of die castings shall conform to the requirements of the die
casting drawings.
4.3.2 The dimensional tolerance of die castings shall meet the requirements of grade
DCTG4 ~ grade DCTG7 in GB/T 6414-2017. For the dimensional tolerance, which is
affected by the parting surface and the movable part of the mold, it needs to add an
additional amount, please refer to Appendix B and Appendix C. When there are special
provisions and requirements, they shall be marked on the drawings.
4.3.3 For the geometric tolerance requirements of die castings, please refer to Appendix
D. Its labeling method shall comply with the provisions of GB/T 1182.
4.3.4 The machining allowance of die castings shall be implemented, in accordance
with the provisions of GB/T 6414-2017. If there are special provisions and requirements,
the machining allowance shall be indicated on the drawing.
4.4 Weight
When the buyer has requirements on the weight of die castings, its weight tolerance
shall comply with the grade MT5 ~ grade MT7 requirements of GB/T 11351-2017.
4.5 Surface quality
4.5.1 The surface roughness of die castings shall conform to the drawings or customer
requirements.
4.5.2 Die castings shall not have penetrating cracks, under-casting or other defects.
They are allowed to have scratches, dents, lack of flesh, mesh-shaped burrs, gray spots,
flow marks and other defects.
4.5.3 There shall be no bulging phenomenon on the mating surface of die castings; the
number and size of such defect, on the non-mating surfaces, which is allowed to exist,
shall be determined, through negotiation between the supplier and the buyer.
4.5.4 If there is no special provision in the drawings, the settings of the die-casting
process, such as the position of the ejector pin, the position of the parting line, the
position of the gate and the overflow port, etc., shall be determined, through negotiation
between the supplier and the buyer.
4.5.5 The surface of the die casting, that needs special treatment, such as polishing, shot
blasting, chrome plating, coating, anodizing, chemical oxidation, etc., shall be indicated
on the drawing.
provisions of GB/T 231.1.
5.2.3 When sampling is required for die castings, the sampling location, specimen
structure and size shall be agreed upon by both the supplier and the buyer.
5.3 Dimensions
5.3.1 The geometric dimension inspection of die castings shall be carried out, in
accordance with the provisions of GB/T 3177.
5.3.2 The geometric tolerance inspection of die castings shall be carried out, in
accordance with the provisions of GB/T 1958.
5.3.3 If the accuracy is met, general or special measuring tools can be used for
inspection.
5.4 Weight
During mass production, it shall randomly take not less than 10 pieces of products from
the blanks; use the average weight of the actual weight is taken as the nominal weight.
5.5 Surface quality
5.5.1 The surface quality of die castings shall be inspected by visual method or by other
suitable methods.
5.5.2 The surface roughness of the die castings shall be tested by comparing the sample
blocks.
5.6 Internal quality
5.6.1 The test methods for the internal quality of die castings may include non-
destructive testing, pressure test, metallographic inspection, cutting inspection, etc.
5.6.2 Corresponding quality inspection shall be carried out for the die castings, after
infiltration, repair, deformation correction.
6 Inspection rules
6.1 Inspection items
The inspection of die castings is divided into type test and exit-factory inspection. The
inspection items are as shown in Table 4.
6.4.3 When the size of any specimen is unqualified, it shall be judged as unqualified.
The rest of the products in the same batch are checked one by one.
6.4.4 When the weight of any specimen is unqualified, it shall be judged as unqualified.
The rest of the products in the same batch are checked one by one.
6.4.5 When the surface quality of any specimen is unqualified, it shall be judged as
unqualified.
6.4.6 When the internal quality of any specimen is unqualified, it shall be judged as
unqualified. Check the rest of the same batch one by one.
7 Marking, packaging, transportation, storage
7.1 Product marking
The following marks shall be cast or engraved on non-machined surfaces of the die
castings:
a) Raw material designation;
b) Part number;
c) Customer trademarks or symbols;
d) Manufacturer's brand or symbol;
e) Manufacturing year, month, mold number;
f) Other markings specified by the customer.
7.2 Packaging signs
The outer packaging of die castings shall have the following signs: