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This standard is drafted in accordance with the rules given in GB/T 1.1-2009.
This standard replaces JB/T 6402-2006 Heavy low alloy steel castings, and the following main technical changes have been made with respect to JB/T 6402-2006:
——the order requirements are modified (see Clause 3; Clause 3 of Edition 2006);
——the smelting method of steel for castings is modified (see Sub-clause 4.1; Sub-clause 4.1.1 of Edition 2006);
——the requirements for repair welding are modified (see Sub-clause 4.4.1; Sub-clause 4.1.4 of Edition 2006);
——the definition of major defects is added (see Sub-clause 4.4.2);
——the material designations ZG25Mn, ZG20CrMoV and ZG15Cr1Mo1V are added (see Tables 1 and 2);
——the chemical compositions of ZG20Mn and ZG35Mn are modified (see Table 1; Table 1 of Edition 2006);
——the mechanical property symbols are modified, and some mechanical property indexes of ZG20Mn, ZG30Mn, ZG35Mn, ZG40Mn, ZG40Mn2, ZG35Cr1Mo and ZG42Cr1Mo are modified (see Table 2; Table 2 of Edition 2006);
——the hardness requirement for ZG65Mn and ZG55CrMnMo are added (see Table 2; Table 2 of Edition 2006);
——the requirement for non-destructive testing are added (see Sub-clauses 5.3 and 6.3);
——the requirements for surface quality of castings are modified (see Sub-clause 5.4.2; Sub-clause 4.4.2 of Edition 2006);
——the requirements for chemical composition analysis are modified and the requirements for spectral analysis method and arbitration analysis are added (see Sub-clause 6.1; Sub-clause 5.1 of Edition 2006);
——the rules of impact test are modified, and the single value of impact absorbed energy shall not be less than "2/3" of the specified value is modified to it shall not be less than "70%" of the specified value (see Sub-clause 6.2.4; Sub-clause 5.2.4 of Edition 2006);
——the requirements for evaluation of surface roughness are modified (see Sub-clause 6.4; Sub-clause 5.4 of Edition 2006);
——the requirements for retest and re-heat treatment are modified (see Sub-clauses 6.5 and 6.6; Sub-clause 5.3 of Edition 2006);
——the contents of quality certificate are modified (see Clause 7; Clause 6 of Edition 2006);
This standard was proposed by the China Machinery Industry Federation.
This standard is under the jurisdiction of the National Technical Committee 506 on Heavy Casting and Forging of Standardization Administration of China (SAC/TC 506).
The previous editions of this standard are as follows:
——JB/T 6402-1992 and JB/T 6402-2006.
Heavy low alloy steel castings - Technical specification
1 Scope
This standard specifies the order requirements, manufacturing process, technical requirements, inspection rules, test methods, quality certificate, marking and packaging of general heavy low alloy steel castings (hereinafter referred to as castings).
This standard is applicable to the castings cast in a sand mould or poured in a mould with similar thermal conductivity.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 222 Permissible tolerances for chemical composition of steel products
GB/T 223 (all parts) Methods for chemical analysis of iron, steel and alloy
GB/T 228.1 Metallic materials - Tensile testing - Part 1: Method of test at room temperature
GB/T 229 Metallic materials - Charpy pendulum impact test method
GB/T 231.1 Metallic materials - Brinell hardness test - Part 1: Test method
GB/T 4336 Carbon and low-alloy steel - Determination of multi-element contents - Spark discharge atomic emission spectrometric method (routine method)
GB/T 11352 Carbon steel castings for general engineering purpose
GB/T 15056 Casting surface roughness - Appraising method
GB/T 20066 Steel and iron - Sampling and preparation of samples for the determination of chemical composition
JB/T 5000.6 Heavy mechanical general techniques and standards - Part 6: Steel castings
JB/T 5000.7 Heavy mechanical general techniques and standards - Part 7: Repair welding for steel castings
JB/T 6397-2006 Specification for the heavy carbon structural steel forgings
3 Order requirements
3.1 The purchaser shall specify name, material designation, technical requirements, inspection items, delivery condition and supply quantity of the castings in the order contract.
3.2 The purchaser shall provide the order drawings and technical conditions agreed by the supplier and the purchaser.
3.3 Special requirements or other additional requirements proposed by the purchaser, if any, shall be agreed between both parties.
4 Manufacturing process
4.1 Smelting
Steel for the castings shall be smelted in induction furnace, electric arc furnace, electric furnace and refined outside the furnace or in other smelting methods that meet the requirements confirmed by the supplier and the purchaser.
4.2 Casting
If the purchaser has no special requirements, the casting process shall be determined by the supplier.
4.3 Heat treatment
The castings shall be subjected to heat treatment. Unless otherwise specified, the supplier may carry out heat treatment according to the mechanical property requirements.
4.4 Repair welding
4.4.1 If allowed by the purchaser, the repair welding of casting defects can be carried out by the supplier. Unless otherwise specified, the repair welding shall be carried out in accordance with JB/T 5000.7, and the repair welding process shall be determined by the supplier.
4.4.2 Defects with a depth of groove greater than 25 mm or 20% of the thickness of the section, whichever is less, or defects with a single area greater than 6,500 mm2 prepared for repair welding shall be considered as major defects and the repair welding of major defects shall be recorded.
4.5 Straightening
Deformation caused by castings can be eliminated by straightening, which is usually carried out at room temperature, and heat straightening can be used under special circumstances.
5 Technical requirements
5.1 Chemical composition
5.1.1 The chemical composition of the steel (melting analysis) shall meet those specified in Table 1.
Table 1 Chemical composition
(mass fraction, %)
Material designation C Si Mn P S Cr Ni Mo V Cu
Material designation C Si Mn P S Cr Ni Mo V Cu
5.1.2 Residual element content (mass fraction): Ni≤0.30%, Cr≤0.30%, Cu≤0.25%, Mo≤0.15%, V≤ 0.05%, total residual element content ≤ 1.0%. If not required by the purchaser, the residual elements will not be used as the basis for acceptance.
5.1.3 If required by the purchaser, the chemical composition analysis of finished products may be carried out, and the permissible deviation of its chemical composition shall meet the requirements of GB/T 222.
Foreword i
1 Scope
2 Normative references
3 Order requirements
4 Manufacturing process
4.1 Smelting
4.2 Casting
4.3 Heat treatment
4.4 Repair welding
4.5 Straightening
5 Technical requirements
5.1 Chemical composition
5.2 Mechanical properties
5.3 Non-destructive testing
5.4 Surface quality of castings
5.5 Shape and dimensional tolerance
6 Inspection rules and test methods
6.1 Chemical composition analysis
6.2 Mechanical property test
6.3 Non-destructive testing
6.4 Surface roughness
6.5 Retest
6.6 Re-heat treatment
7 Quality certificate
8 Marking and packaging
Table 1 Chemical composition
Table 2 Mechanical properties
