JB/T 6402-2018Heavy low alloy steel castings - Technical specification (English PDF)

3.3 When the purchaser proposes special requirements or other supplementary

requirements, it shall be agreed between the supplier and the purchaser.

4.1 Smelting

Steel for castings shall be smelted by induction furnace, electric arc furnace, electric furnace and refined outside the furnace or adopt other melting methods that meet the requirements confirmed by both the supplier and the purchaser.

4.2 Casting

When the purchaser has no special requirement, the casting process shall be determined by the supplier.

4.3 Heat treatment

Castings shall be heat treated. Unless otherwise specified, the supplier may perform heat treatment according to the requirements of mechanical properties.

4.4 Repair welding

4.4.1 When the purchaser permits repair welding of casting defects, the supplier

may repair of casting defects. Unless otherwise specified, repair welding shall be performed in accordance with the provisions of JB/T 5000.7. The process of

5.4 Surface quality of casting

5.4.1 The surface roughness of castings shall meet the requirements of drawings or order agreements. In general, the surface roughness Ralpha shall be less than or equal to 100 pm.

5.4.2 The surface of the casting shall be free from defects that affect its use.

5.5 Shape and dimensional tolerances

The dimensional tolerances and machining allowances of castings shall comply with the provisions of drawings or order agreements. If there are no requirements in the drawings or order agreements, the machining allowances and dimensional tolerances of castings shall comply with the provisions of JB/T

5000.6.

6.1 Analysis of chemical composition

6.1.1 When there is no special agreement between the supplier and the purchaser, samples for chemical composition analysis of the casting shall be taken from the ladle during the pouring process or before tapping; one sample shall be taken from each ladle. When one piece is casted by multi-ladles, the chemical composition of the castings is calculated using the weighted average analysis method.

6.1.2 Sampling and sample preparation for chemical composition analysis shall be performed in accordance with the provisions of GB/T 20066.

6.1.3 Conventional chemical composition analysis shall be performed in accordance with GB/T 223; spectral analysis shall be performed in accordance with GB/T 4336; arbitration analysis shall be performed in accordance with

GB/T 223.

6.2 Mechanical property test

6.2.1 The test blocks for mechanical property tests are in accordance with GB/T

11352. When there is no special agreement between the supplier and the purchaser, the use of individual or auxiliary test blocks shall be determined by the supplier.

unsatisfactory, it may take double quantity of samples for retesting in the adjacent position near the failed test block. The retest results shall meet the requirements in Table 2. Otherwise, the supplier may deal with them in accordance with the provisions of 6.6.

6.6 Reheat treatment

When the retest results still do not meet the requirements in Table 2, the castings and test blocks may be heat treated again, but the reheat treatment shall not be more than 2 times (the number of tempering is unlimited). After reheating, the test shall be repeated as specified in 6.2 and 6.3.