GB/T 9437-2009Heat resistant iron castings (English PDF)

3.1 Designation and chemical composition of heat resistant cast iron

The designation method of heat resistant cast iron conforms to the provisions of GB/T 5612. There are 11 designations in total.

3.2 Geometric dimensions, machining allowances and weight tolerances

The geometric shape and size of the casting shall meet the requirements of the drawing.

Its dimensional tolerance and machining allowance shall comply with the provisions of GB/T 6414. Its weight deviation shall comply with the provisions of GB/T 11351.

3.3 Surface quality

3.4 Mechanical properties

The mechanical properties of castings at room temperature shall meet the requirements in Table 2. See Annex A for short-time high temperature tensile properties.

3.5 Heat treatment

Silicon-based and aluminum-based heat resistant ductile iron castings shall generally undergo heat treatment to eliminate residual stress. However, when the silicon-molybdenum heat resistant ductile iron castings have a pearlite content of less than 15%, heat treatment is not required.

See Annex B for the service conditions of heat resistant cast iron.

3.6 Metallographic structure

For the metallographic structure of heat resistant cast iron, refer to the provisions of GB/T 9441 and GB/T 7216. The specific requirements shall be negotiated by both parties. For silicon-based heat resistant cast iron, the matrix structure shall be mainly ferrite.

3.8 Special requirements

When the purchaser has requirements for magnetic particle testing, ultrasonic testing, ray testing, it shall be agreed between the supplier and the purchaser.

4.1 Chemical composition analysis

4.1.1 Chemical composition analysis can be carried out by conventional chemical analysis method or photoelectric direct reading spectroscopic analysis method.

4.1.2 Sampling methods for conventional chemical analysis shall be carried out in accordance with the provisions of GB/T 20066.

4.2 Mechanical properties test

Cast iron designation Minimum tensile strength Rm/MPa Hardness / HBW

4.2.1 The room temperature mechanical property test of HTRCr, HTRCr2, HTRSi5 and other designations, including the preparation of specimens, shall be carried out in accordance with the provisions of GB/T 228.

4.3 Test blocks, specimens

4.3.1 The shape and size of the Y-shaped single-cast test block used in the tensile test of QTRSi4, QTRSi5, QTRSi4Mo, QTRSi4Mo1, QTRAl4Si4, and QTRAl5Si5 are shown in Figure 1 and Table 3 (the hatched line in Figure 1 is the position where the specimen is cut). Generally, choose type II. The test blocks in Annex C can also be used.

The shape and size of single-cast easy-cut test blocks used by QTRA122 and HTRCr16 are shown in Figure 2.

4.4 Anti-oxidation and anti-growth test

Anti-oxidation and anti-growth tests of heat resistant cast iron shall be carried out in accordance with the provisions of Annex D and Annex E.

4.5 Thermal expansion coefficient test

Refer to Annex F for the test method of thermal expansion coefficient.

4.6 Heat treatment

In addition to eliminating the internal stress of the casting, if the casting is subjected to other heat treatments, the test block shall also undergo heat treatment in the same furnace or process.

5.1 Composition of sampling batch

5.1.1 Castings poured from the same furnace of molten iron produced by the same mold constitute a sampling batch.

5.1.2 The maximum weight of each sampling batch is 2000kg of casting after cleaning.

The sampling batch can be changed upon negotiation between the supplier and the purchaser.

5.1.5 When continuously melting a large amount of molten iron of the same designation, the maximum weight of each sampling batch shall not exceed the weight of castings poured within 2h.

5.2 Sampling for chemical composition

Each sampling batch shall be analyzed once for chemical composition. The analysis results shall meet the requirements in Table 1.

5.3 Sampling for casting size

The first batch of castings and important castings shall be checked on each piece for size, geometry and surface roughness. General castings can be spot-checked. The method of spot check shall be agreed upon by the supplier and the purchaser.

5.6 Evaluation of mechanical performance test results

When testing the tensile strength, if the test result of the first tensile sample fails to meet the requirements, and it is not caused by the reasons listed in 5.7, then two other specimens from the same batch can be taken for reinspection.

5.7 Validity of test

If the test result does not meet the requirements due to one of the following reasons rather than the quality of the casting itself, the test shall be invalid.

5.8 Heat treatment of test blocks and castings

Unless otherwise specified, if the castings are supplied in the as-cast state and their mechanical properties do not comply with this Standard, with the agreement of the purchaser, the supplier can conduct heat treatment together with the batch of castings and its representative test block. Then retest.