GB/T 37400.5-2019Heavy machinery general technical specification - Part 5: Non-ferrous metal castings (English PDF)

3.8 Repair of defects

3.8.1 If the defect is in the following situations, it shall not be repaired:

a) Pressure-bearing or sealing parts in contact with flammable, explosive or highly toxic substances;

b) Locations subject to high temperature, high pressure, strong corrosion;

c) Threaded parts, the main load-bearing parts of heavy loads;

d) Cold partitions on castings and severe defects such as sand holes, blisters, slag holes, shrinkage and slag inclusions.

3.8.2 Except for the conditions specified in 3.8.1, if welding repairs are required and can be performed on castings, it needs to be weld-repaired or repaired by other feasible methods. The defects can be removed by grinding; the size of the casting after grinding shall meet the requirements of the dimensional tolerance of the casting.

3.8.3 When performing welding repair, the surface shall be carefully cleaned and the welding process shall be worked out. The welding-repair area shall be free from defects such as cracks, lack of penetration, lack of welding. The castings shall be welded in the as-cast state. For the castings that need to be welded after heat treatment, the heat treatment shall be performed in the original state after welding. For the heat-treated castings, it shall re-inspect the performance of single-cast or attached casting samples.

3.8.4 If the casting is deformed, it can be corrected. After correction, it shall check its geometry and the presence of cracks.

3.8.5 When the repaired parts of castings have requirements for water pressure and airtightness, relevant tests shall be carried out at

1.2 times the specified test pressure after repair. for inspection.

5.2.3 When the same alloy in different smelting furnaces is poured into a casting, if it meets the requirements of 5.2.2, it can be regarded as a batch for inspection. Otherwise, the mechanical properties of the single-cast samples shall be checked for each melting furnace.

5.3 Specimens

5.3.1 The shape and size of single-cast samples of copper and copper alloy castings shall comply with the provisions in Appendix A of GB/T 1176-2013.

5.3.2 The shape and size of single-cast samples of aluminum alloy castings shall comply with the provisions in Appendix B of GB/T 1173-2013.

5.3.3 The shape and size of single-cast samples of zinc alloy castings shall comply with the provisions of

4.4 in GB/T 1175-1997.

5.3.4 The casting mold of the single-cast sample shall use the same casting material as the casting, meanwhile it shall be poured in the same batch as the casting. For castings that need to be supplied after heat treatment, single-cast samples shall be heat-treated together with the casting.

5.3.5 If the test result is unqualified due to the defect of the sample, it shall take sample again for testing. If there is no spare sample, it can take sample from the main sample. The cutting position and size from the main sample shall be agreed between the supplier and the purchaser.

5.3.6 The average value of the tensile strength of the main sample shall not be less than 80% of the single-cast sample; the elongation shall not be less than 50% of the single-cast sample.

5.4 Number of tests, evaluation and re-inspection of test result

5.4.1 The number of tests for chemical composition and mechanical properties is one sample per batch. If there are special requirements for the number of tests, it shall be decided by the supplier and the buyer through consultation.

5.4.2 It requires one group (2 pcs) of samples for chemical composition. It allows to test one piece at the first time. If one of them meets the requirements, the batch of castings will be qualified. If the analysis results of the two samples are both unqualified, the batch of castings is unqualified.

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