GB/T 16746-2018Zinc alloy castings (English PDF)

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.

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.

6.1 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.

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.

7.1 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; […]