JB/T 6402-2018 English PDF (JBT6402-2018)
JB/T 6402-2018 English PDF (JBT6402-2018)
JB/T 6402-2018: Heavy low alloy steel castings -- Technical specification
MECHANICAL INDUSTRY STANDARD
OF THE PEOPLE’S REPUBLIC OF CHINA
Filing number: 61736-2018
Replacing JB/T 6402-2006
Heavy low alloy steel castings -
ISSUED ON: FEBRUARY 09, 2018
IMPLEMENTED ON: OCTOBER 01, 2018
Issued by: Ministry of Industry and Information Technology of PRC
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative references ... 5
3 Order requirements ... 6
4 Manufacturing process ... 6
4.1 Smelting ... 6
4.2 Casting ... 6
4.3 Heat treatment ... 6
4.4 Repair welding ... 6
4.5 Correction ... 7
5 Technical requirements ... 7
5.1 Chemical composition ... 7
5.2 Mechanical properties ... 10
5.3 Nondestructive testing ... 11
5.4 Surface quality of casting ... 12
5.5 Shape and dimensional tolerances ... 12
6 Inspection rules and test methods ... 12
6.1 Analysis of chemical composition ... 12
6.2 Mechanical property test ... 12
6.3 Nondestructive testing ... 13
6.4 Surface roughness ... 13
6.5 Retesting ... 13
6.6 Reheat treatment ... 14
7 Certificate of quality ... 14
8 Marking and packaging ... 14
This standard was 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". As compared with JB/T 6402-2006, the main technical changes are as follows: - MODIFY the order requirements (see Chapter 3; Chapter 3 of the 2006
- MODIFY the melting method of steel for casting (see 4.1; 4.1.1 of 2006 edition);
- MODIFY the provision for repair welding (see 4.4.1; 4.1.4 of 2006 edition); - ADD the definition of major defects (see 4.4.2);
- ADD the material designations ZG25Mn, ZG20CrMoV, ZG15Cr1Mo1V (see
Tables 1 and 2);
- MODIFY the chemical composition of ZG20Mn and ZG35Mn (see Table 1;
Table 1 of 2006 edition);
- MODIFY the mechanical performance symbols; MODIFY some of the
mechanical performance indicators of ZG20Mn, ZG30Mn, ZG35Mn,
ZG40Mn, ZG40Mn2, ZG35Cr1Mo and ZG42Cr1Mo (see Table 2; Table 2
of the 2006 edition);
- ADD the hardness requirements for ZG65Mn and ZG55CrMnMo (see Table
2; Table 2 of the 2006 edition);
- ADD the requirements for non-destructive testing (see 5.3, 6.3);
- MODIFY the requirements for the surface quality of castings (see 5.4.2; 4.4.2 of the 2006 edition);
- MODIFY the requirements for chemical composition analysis; ADD the
requirements for spectral analysis methods and arbitration analysis (see 6.1; 5.1 of the 2006 edition);
- MODIFY the rules of the impact test, to change that “the single value of the impact absorption energy shall be not less than 2/3 of the specified value to "70%" (see 6.2.4; 5.2.4 of the 2006 edition);
- MODIFY the requirements for the evaluation of surface roughness (see 6.4; 5.4 of the 2006 edition);
Heavy low alloy steel castings -
This standard specifies the order requirements, manufacturing processes, technical requirements, inspection rules and test methods, quality certificates, markings and packaging for general heavy low-alloy steel castings (hereinafter referred to as castings).
This standard applies to castings as casted in sand molds or molds with similar thermal conductivity to sand molds.
2 Normative references
The following documents are essential to the application of this document. For the dated documents, only the versions with the dates indicated are applicable to this document; for the undated documents, only the latest version (including all the amendments) are applicable to this standard.
GB/T 222 Permissible tolerances for chemical composition of steel products GB/T 223 (All parts) Methods for chemical analysis of steel and alloys
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 the name of the casting, material designations, technical requirements, inspection items, delivery status and quantity of supply in the order contract.
3.2 The purchaser shall provide order drawings and technical conditions approved by both the supplier and the purchaser.
3.3 When the purchaser proposes special requirements or other supplementary requirements, it shall be agreed between the supplier and the purchaser. 4 Manufacturing process
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 Rα 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 Inspection rules and test methods
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.
7 Certificate of quality
Upon delivery, the supplier shall provide the quality certificate to the purchaser. The quality certificate shall include the following:
a) Order contract number;
b) Drawing number;
c) Name of the casting;
d) Weight of the casting;
e) Product implemented standard number and material designation;
f) Casting’s identification number or melting furnace number;
g) Chemical composition analysis report and mechanical property test report, etc.;
h) Heat treatment status, heat treatment curve record, heat treatment
furnace batch number;
i) Records of major defects and repair welding (including sketches of
positions and dimensions);
j) Other inspection reports required in contracts and technical agreements. 8 Marking and packaging
8.1 Castings shall be identified by supplier identification, order contract number, furnace number, production batch number, part number, etc.