GB/T 9439-2023Grey iron castings (English PDF)

4.1 The method of expressing gray iron casting material designation shall comply with

the provisions of GB/T 5612.

4.2 For the designation of gray iron casting material, based on the minimum tensile

strength value measured on a tensile specimen processed from a single-cast sample, which has a diameter of dia. 30 mm, the gray iron casting is divided into 8 designations.

HT100, HT150, HT200, HT225, HT250, HT275, HT300, HT350, see Table 1.

5.1 The production method and chemical composition of gray iron castings are

determined by the supplier. The chemical composition is not used as a basis for acceptance of castings; however, the selection of chemical compositions shall ensure the mechanical properties and metallographic structure of the castings.

5.2 If the technical conditions of the buyer include acceptance requirements for

chemical components, they shall be implemented in accordance with the requirements Material designation Relevant wall thickness t

5.3 Unless otherwise specified, castings are delivered as cast.

6.1 Mechanical properties

6.1.1 Tensile strength

6.1.1.1 The tensile strength value of the tensile specimen shall comply with the

requirements in Table 1.The mechanical properties and physical properties of single-cast samples are as shown in Appendix A.

6.1.1.2 The tensile strength in Table 1 is related to the relevant wall thickness. Usually

dia. 30 mm single-cast sample is used to test the tensile strength.

6.1.1.3 The relationship between the tensile strength and Brinell hardness of gray iron

casting is as shown in Appendix B.

6.1.1.4 If the acceptance items are not clearly specified in the order agreement, the

supplier shall use tensile strength as the main basis for acceptance.

6.1.2 Tensile strength of casting body

6.1.2.1 If tensile specimens are cut out and processed from the casting body, the supplier

and the buyer shall agree on.

- Sampling location;

- The minimum tensile strength value or allowable range value of the bulk specimen.

Note 1.The physical performance values of castings cannot be unified, because they are closely related to factors such as the complexity of the casting, the wall thickness of the casting, the cooling rate.

Note 2.The tensile properties of casting body specimens are not only affected by material properties, but also by defects in the sampling location.

6.1.2.2 The relationship between the tensile strength, Brinell hardness and wall

thickness of the casting body is shown in Appendix C. The expected value of the tensile strength of the casting body is shown in Table C.1.

6.1.3 Hardness

6.1.3.1 Gray iron casting, which is classified according to hardness, is mainly applicable

to gray iron casting parts, which have cutting performance or wear resistance as the main evaluation index. The hardness value of gray iron castings shall comply with the requirements in Table 2.

6.1.3.2 Castings with main wall thickness t > 80 mm are not classified according to

hardness.

6.1.3.3 Unless otherwise specified, HBW represents the Brinell hardness, which is

measured under the test condition of 10/3000.

6.1.3.4 If hardness is used as an acceptance item, the supplier and the buyer shall agree

on the location of the relevant wall thickness and hardness testing; clearly specify it in the order agreement. Hardness can also be tested on the specimen. Figure C.2 gives the relationship between the average hardness and the relevant wall thickness in simple shapes.

6.2 Metallographic structure

6.2.1 The graphite form of gray iron castings is mainly A-type graphite, wherein the A-

type graphite accounts for more than 90%. The total amount of carbide and phosphorus eutectic in the matrix structure shall be less than 1%.

6.2.2 When the purchaser has clear requirements on the matrix structure and graphite

shape, quantity, distribution size, grade, phosphorus eutectic content, carbide content in the metallographic structure, the purchaser's technical requirements shall be met.

6.3 Machining allowances, dimensions, dimensional tolerances, geometric shapes, geometric tolerances If the buyer has no special requirements, the machining allowance, dimensional tolerance, geometric tolerance of castings shall be selected according to the provisions of GB/T 6414.

6.4 Weight tolerance

If the buyer has no special requirements, the weight tolerance of castings shall be selected according to the provisions of GB/T 11351.

6.5 Surface quality

6.5.1 If the buyer has no special requirements, the surface roughness value of the casting

shall be within the range specified in GB/T 6060.1.

6.5.2 The castings shall be cleaned; the excess parts shall be trimmed; the residue of the

pouring riser, core bone, sticky sand, inner cavity residues shall be removed. The allowable pouring and riser residues, draped seams, flying burr residues, internal cavity cleanliness, etc. of castings shall comply with the purchaser's drawings, technical requirements or ordering agreement.

7.1 General

7.1.1 The test sample shall be poured from the same ladle (or furnace) of molten iron

as the casting it represents.

7.1.2 When a casting requires heat treatment, the test sample shall be heat treated in the

same furnace as the casting it represents.

7.1.3 All test samples shall be clearly marked to ensure quality traceability.

7.2 Specimen types

7.2.1 The specimen type (single-cast sample, side-by-side cast sample, attached cast

sample, body specimen) shall be selected based on the weight and wall thickness of the casting. Unless both the supplier and the buyer have determined the relevant wall thickness and the specimen type, the specimen type shall be determined by the supplier.

7.2.2 When the mass of the casting exceeds 1000 kg and the relevant wall thickness

exceeds 50 mm, attached cast samples shall be used first. The size and location of the test samples shall be agreed upon by the supplier and the buyer.

7.2.3 In order to ensure that the performance is achieved, the type II test samples in

Figure 1 is usually used.

7.3 Tensile test samples

7.3.1 Test sample dimensions

7.3.1.1 The dimensions of single-cast samples and side-by-side cast samples are as

shown in Figure 1.The dimensions of the samples shall correspond to the relevant wall thickness. The dia. 30 mm type II test samples in Figure 1 can also be used to characterize the material.

7.3.1.2 If other sizes are used, the size of the specimen and the measured minimum

tensile strength value or allowable range value shall be agreed upon by both parties.

Description of index symbol.

D - Single-cast sample's sprue cup opening diameter;

H - Height of sprue cup of single-cast sample;

L - Length of single-cast sample;

A - The amount of sand contained at the bottom of the single-cast sample or between the test samples;

d - Diameter of single-cast sample.

7.3.2 Detection frequency and quantity

The sampling frequency of specimens representing casting materials shall be consistent with the supplier's quality control requirements, or shall be agreed upon by both the supplier and the buyer.

7.3.3 Single-cast sample

7.3.3.1 Single-cast samples are prepared according to Figure 1; the test samples shall

be cast vertically. The test samples and castings shall be poured from the same batch of molten iron; the test samples shall be poured at the end of the batch of molten iron.

7.3.3.2 The single-cast sample shall be cast in a mold with a similar thermal

conductivity to the casting it represents. Three or more test samples can be poured into the same mold at the same time. The minimum sand consumption between the test samples shall be greater than 40 mm.

7.3.3.3 The unpacking sand-out temperature of single-cast samples shall be lower than

500 °C. After negotiation and agreement between the supplier and the buyer, if the castings are shaken out when the temperature is higher than 500 °C, the single-cast samples can also be unpacked and shaken out when the temperature is higher than 500 °C.

7.3.3.4 If the casting requires heat treatment, the test samples shall be treated in the

same furnace as the casting it represents; when the casting is subjected to stress-relieving aging treatment, the test samples may not be treated.

7.3.3.5 The length L of the test sample is determined according to the length of the test

sample and the clamping device, as shown in Figure 1.The length L of the test sample depends on the type A or B test sample (see 8.1.3), as well as the length of the clamping section. The dimensions of the specimens processed with single-cast samples are as shown in Table 3.

7.3.3.6 Test samples of other sizes or produced using other casting processes shall be

agreed upon by both the supplier and the buyer. Figure C.1 shows the relationship between the minimum tensile strength and the main wall thickness of castings of simple shapes.

7.3.4 Side-by-side cast samples

7.3.4.1 Side-by-side cast samples represent castings of the same batch that are cast in

the same batch and have similar relevant wall thicknesses. The test samples shall be cast at the end of the same batch of castings.

7.3.4.2 The dimensions of the side-by-side cast samples are as shown in Figure 1.

7.3.5 Attached cast samples

7.3.5.1 The attached cast sample represents the attached casting and the same batch of

7.3.6 Casting bulk specimen

7.3.6.1 If necessary, both the supplier and the purchaser can specify the performance of

the specified position of the casting; prepare specimens at the specified locations and test the mechanical properties of the specimens.

7.3.6.2 The size of the bulk specimen shall be selected according to Table 3, OR it shall

be agreed upon by both the supplier and the buyer through negotiation.

7.3.6.3 If the purchaser does not specify, the sampling position of the bulk specimen

shall be determined by the supplier itself.

8.1 Tensile test

8.1.1 The tensile test shall be carried out in accordance with the provisions of GB/T

228.1.

8.1.2 There are two types of tensile test specimens, type A and type B. The type of

tensile test specimens shall be as shown in Figure 5 or Figure 6.

Note. For the same material, the test results of Type A specimens may be slightly higher than the test results of Type B specimens.

8.1.3 See Table 3 for tensile specimen dimensions. Both ends of the specimen can be

processed into threaded or cylindrical shapes, to meet the needs of the clamping device.

Unit is millimeters a) Type A specimen with threaded clamping end b) Type A specimen with cylindrical clamping end Description of index symbol.

Ls - Length of threaded clamping end;

Lp - Length of cylindrical clamping end;

M - Thread diameter of clamping end;

dia. d - Diameter of gauge section of test sample;

dia. d1 - Diameter of cylindrical clamping end.

Figure 5 -- Type A specimen

Unit is millimeters a) Type B specimen with threaded clamping end b) Type B specimen with cylindrical clamping end Description of index symbol.

Ls - Length of threaded clamping end;

Lp - Length of cylindrical clamping end;

Lc - Length of the gauge section of the specimen;

M - Thread diameter of clamping end;

dia. d - Diameter of specimen gauge section;

dia. d1 - Diameter of cylindrical clamping end.

8.2 Hardness test

8.2.1 The hardness measurement method shall be carried out in accordance with the

provisions of GB/T 231.1.The hardness test with a test force-ball diameter square ratio of 30 or 10 shall be preferred.

8.2.2 When testing the hardness, the test shall be conducted below 1.5 mm from the

casting surface.

9.1 Group-batching

Casting inspection batches are divided as follows.

a) Castings produced by the same mold and poured from the same molten iron in the same furnace constitute a sampling batch.

b) Castings poured from the same molten iron package constitute a sampling batch.

c) Castings with a total mass of 2000 kg form a sampling batch.

d) If the mass of a single piece is greater than 2000 kg, it can be a separate sampling batch.

e) When a large amount of molten iron is continuously melted, the maximum mass of each sampling batch shall not exceed the mass of the castings poured within 2 hours.

f) If a designation of molten iron has a large melting capacity, it adopts system-controlled melting technology and strict production process control, meanwhile it can carry out certain forms of rapid pre-furnace inspection and quality control on a package (furnace) basis, such as white opening testing, spectral composition analysis, thermal analysis, composition adjustment, etc., THEN, upon agreement between the supplier and the buyer, several batches of castings can also be used to constitute a sampling batch.

g) During continuous production, such as when the charge, process conditions, or chemical composition change, all castings poured with continuously molten iron during this period, no matter how short the time interval, are regarded as a sampling batch.

9.2 Chemical composition analysis

Chemical composition shall be tested batch by batch, based on sampling batches.

9.3 Tensile strength test

The specimens used for mechanical property testing shall be taken from the test sample (block) or the casting body; a tensile test shall be conducted for each sampling batch.

9.4 Hardness test

The hardness test can be carried out on the casting body or on the tensile specimen or hardness test block. Each sampling batch shall be tested once for hardness.

9.5 Validity of test

When the test results do not meet the requirements due to one of the following reasons, the test shall be repeated and the data of the defective sample shall be replaced by the obtained results.

a) The specimen is improperly installed on the testing machine or the testing machine is operated improperly.

b) There are casting defects on the surface of the specimen or improper cutting of the specimen (such as specimen size, transition fillet, roughness that does not meet the requirements, etc.).

c) The specimen breaks outside the gauge length (parallel section).

d) There are casting defects on the fracture surface after the specimen is broken.

9.6 Judgment of test and retest results

9.6.1 When testing the tensile strength, first use a tensile specimen to test. If it meets

the requirements, the batch of castings will be qualified in terms of material. If the test results do not meet the requirements, two more samples can be taken from the same batch of specimens for reinspection.

10 Marking, quality certificate, surface protection, packaging, storage and transportation

10.1 Casting marking

10.1.1 If the size of the casting allows, the supplier's code, trademark, part code, production date, production sequence number, etc. shall be marked on the non-machined surface.

10.1.2 If the buyer does not have clear requirements for the location, size (font size, font height, convex and concave) and method of the marking, the supplier shall determine by itself.

10.1.3 When it is not possible to mark the castings, the marking may be printed on the

label attached to each batch of castings.