Specification for 28Cr2Mo, 26SiMnMo and 22SiMn2TiB steel plates for armour use
1 Scope
1.1 Main contents
This specification specifies the requirements, quality assurance provisions, and delivery preparation for rolled homogeneous armour steel plates of 28Cr2Mo (code GY4), 26SiMnMo (code GY5), and 22SiMn2TiB (code 616) used for armoured vehicles.
1.2 Scope
This specification is applicable to 28Cr2Mo steel plates with the thickness of 10, 12, 15, 20, 25 or 30 mm, 26SiMnMo steel plates with the thickness of 5, 6, 8, 10, 12, 15 or 20 mm and 22SiMn2TiB steel plates with the thickness of 4, 5, 6, 8, 10, 12, 15, 16, 18, 20 or 22 mm used for armoured vehicles.
2 Normative references
GB 222-84 Method of sampling steel for determination of chemical composition and permissible variations for product analysis
GB/T 229-1994 Metallic materials - Charpy notch impact test
GB 231-84 Metallic materials - Brinell hardness test
GB/T 247-1997 General rule of acceptance, package, mark and certification for steel plates (sheets) and strips
GB 709-88 Dimension, shape, weight and tolerance for hot-rolled steel strip, plate and sheet
GJB 59.18-88 Test operations procedure for armoured vehicles - Armour plate bullet-proof test
ZBY 230-84 Commonly used specification A-mode ultrasonic flaw detector using pulse echo technique
See Annex A (Supplementary) for the reference standards of chemical analysis methods of relevant elements.
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3 Requirements
3.1 Smelting method
GY4 and GY5 steel shall be smelted by the electric arc furnace, while 616 steel shall be smelted by converter and secondary refining or electric arc furnace. As agreed by the supplier and the purchaser and specified in the contract, other methods that can meet the requirements of this specification can also be used for smelting.
3.2 Chemical composition
3.2.1 The designation and chemical composition (smelting analysis) of steel shall meet those specified in Table 1.
Table 1
Note: Delivery is allowed when the content of acid-soluble boron is 0.0003% to 0.0005%.
3.3.2 The permissible deviations of the chemical composition of the steel plate shall meet those specified in Table 2 of GB 222.
3.3 Delivery state
The steel plate shall be delivered in the high-temperature tempered state.
3.4 Mechanical properties
3.4.1 Hardness
The Brinell hardness of the steel plate and quenched and tempered fracture specimens in the delivery state shall meet those specified in Table 2.
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Table 2
Designation Code Steel plate thickness Brinell hardness, HBS10/3000
Specimen in the delivery state Quenched and tempered fracture specimen
Hardness Impression diameter
mm Hardness Impression diameter
mm
28Cr2Mo GY4 10~20 ≤ 269 ≥ 3.70 - -
25, 30 ≤ 269 ≥ 3.70 341~285 3.30~3.60
26SiMnMo GY5 5~20 ≤ 269 ≥ 3.70 - -
22SiMn2TiB 616 4~22 ≤ 269 ≥ 3.70 - -
3.4.2 Impact absorption energy
After heat treatment, the GY4 steel plate with a thickness of not less than 25 mm and the 616 steel plate with a thickness greater than 10 mm shall be tested for Charpy V-notch impact absorption energy at -40°C, but it shall not be used as a basis for delivery.
3.4.3 Heat treatment process
See Table 3 for the recommended heat treatment processes for GY4 and 616 steel plate specimens.
1 Scope
2 Normative references
3 Requirements
4 Quality assurance requirements
5 Delivery preparation
6 Instructions
Annex A (Supplementary) Reference standards of chemical analysis methods
Annex B (Supplementary) Ultrasonic inspection method
Annex C (Supplementary) Method for determination of bullet speed for shooting test
