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GB/T 40883-2021 English PDF (GBT40883-2021)

GB/T 40883-2021 English PDF (GBT40883-2021)

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GB/T 40883-2021: Microalloyed steel forgings -- General specification
This Document specifies the technical requirements, test methods, inspection rules, markings, accompanying documents, packaging, transportation and storage of microalloyed steel forgings. This Document applies to microalloyed steel forgings with a maximum section thickness of no more than 200mm.
GB/T 40883-2021
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS77.140.85
CCS J 32
Microalloyed Steel Forgings – General Specification
ISSUED ON. NOVEMBER 26, 2021
IMPLEMENTED ON. JUNE 01, 2022
Issued by. State Administration for Market Regulation;
Standardization Administration of the People’s Republic of China.
Table of Contents
Foreword... 3
1 Scope... 4
2 Normative References... 4
3 Terms and Definitions... 5
4 Technical Requirements... 5
5 Test Methods... 9
6 Inspection Rules... 10
7 Markings, Accompanying Documents, Packaging, Transportation and Storage... 10 Appendix A (Normative) Supplementary Requirements... 12
Bibliography... 13
Microalloyed Steel Forgings – General Specification
1 Scope
This Document specifies the technical requirements, test methods, inspection rules, markings, accompanying documents, packaging, transportation and storage of microalloyed steel forgings. This Document applies to microalloyed steel forgings with a maximum section thickness of no more than 200mm.
2 Normative References
The provisions in following documents become the essential provisions of this Document through reference in 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) is applicable to this Document.
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 224 Determination of Depth of Decarburization of Steel
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 2975 Steel and Steel Products - Location and Preparation of Samples and Test Pieces for Mechanical Testing
GB/T 6394 Determination of Estimating the Average Grain Size of Metal
GB/T 8170-2008 Rules of Rounding off for Numerical Values and Expression and Judgement of Limiting Values
GB/T 8541 Terminology of Forging and Stamping
GB/T 10561 Steel - Determination of Content of Nonmetallic Inclusions - Micrographic Method Using Standards Diagrams
GB/T 12361 Steel Die Forgings - General Specification
GB/T 12362 Steel Die Forgings - Tolerance and Machining Allowance
GB 13318 General Rules for Safety and Environmental Conservation of Forging Production
GB 13320 Metellographic Grading Atlas and Assessing Method for Steel Die Forgings GB/T 15712 Microalloyed Medium Carbon Steels
GB/T 15822 (all parts) Non-Destructive Testing - Magnetic Particle Testing GB/T 20123 Steel and Iron—Determination of Total Carbon and Sulfur Content Infrared Absorption Method after Combustion in an Induction Furnace (Routine Method) GB/T 20124 Steel and Iron - Determination of Nitrogen Content - Thermal Conductimetric Method after Fusion in a Current of Inert Gas
GB/T 20125 Low-Alloy Steel - Determination of Multi-Element Contents - Inductively Coupled Plasma Atomic Emission Spectrometric Method
GB/T 21469 Machining Allowances and Tolerances for Steel Open Die Forgings on Hammer - General Requirement
JB/T 9179 (all parts) Machining Allowance and Tolerance of Open Die Forgings on Hydraulic Press
3 Terms and Definitions
For the purposes of this Document, the terms and definitions given in GB/T 8541 and the following apply.
3.1 Microalloyed steel forgings
The forgings that use micro-alloyed steel, through the forging process control and post-forging cooling process control, to meet the requirements of mechanical properties. 4 Technical Requirements
4.1 General requirements
4.1.1 Materials
4.1.7.2 When the supplier and the purchaser reach an agreement and the forgings are allowed to only meet the hardness requirements, the hardness level can be marked with "H", such as "60H", "80H", etc.
4.2 Other requirements
4.2.1 Ordering requirements
4.2.1.1 The order shall include. chemical composition, strength level of the product, test method and the number of mechanical property tests for each batch.
4.2.1.2 When the purchaser has a request, the ordering requirements can be determined through negotiation between the supplier and the purchaser.
4.2.1.3 When the purchaser has special requirements, it shall be indicated on the order according to Appendix A.
4.2.2 Process requirements
4.2.2.1 Appropriate hot working process and cooling method shall be selected for forgings to obtain the required mechanical properties.
4.2.2.2 When requested by the purchaser, the supplier shall provide the records of hot working parameters during the forging process, including but not limited to the following parameters. chemical composition of materials (including all microalloyed elements), blanking specifications of forgings, forging temperature and cooling time after forging. 4.2.2.3 After negotiation between the supplier and the buyer.
a) When the hardness of the forging is higher than the specified maximum value or the section elongation is lower than the specified minimum value, it shall be tempered and re-tested;
b) When the hardness of the forging is lower than the specified minimum value or the tensile strength and yield strength are lower than the specified minimum value; heat treatment shall be carried out.
4.2.2.4 For the unproduced billet after the first heating and the forging obtained by reheating and forging, its mechanical properties, depth of decarburization layer, hardness, grain size, etc. shall be negotiated with the purchaser, and can be used only after the purchaser agrees. 4.2.3 Production safety and environmental protection
The production safety and environmental protection requirements of forgings shall comply with the provisions of GB 13318.
5 Test Methods
5.1 Chemical composition of materials
Chemical composition analysis shall be carried out according to general methods such as GB/T 223 (all parts), GB/T 20123, GB/T 20124, GB/T 20125, etc., or take direct reading spectrometer detection.
5.2 Dimensions
Dimensional inspection should use general measuring tools, three-coordinate instruments or three-dimensional scanners for detection.
5.3 Forging streamline
Forging streamlines should be detected by hot acid etching or cold acid etching. 5.4 Surface quality
5.4.1 Appearance inspection may be used for visual inspection.
5.4.2 Surface defects such as folds and cracks should be detected by magnetic particle, and the magnetic particle detection method shall comply with the provisions of GB/T 15822 (all parts). 5.4.3 The residual magnetism of forgings should be detected by a Gauss meter. 5.5 Microstructure
5.5.1 The determination method of grain size shall comply with the provisions of GB/T 6394. 5.5.2 The detection method and evaluation of the depth of the decarburized layer shall comply with the provisions of GB/T 224.
5.5.3 The sampling location and evaluation of metallographic structure shall comply with the provisions of GB/T 13320.When the buyer has a request, the sampling location shall be determined through negotiation between the supplier and the purchaser.
5.6 Mechanical properties
5.6.1 If the purchaser has no special requirements, the test specimens shall be prepared from the forgings after forging and temperature-controlled cooling.
5.6.2 The interception direction of the test specimen shall be parallel to the metal flow direction of the forging; the sampling position and specimen preparation shall comply with the provisions of GB/T 2975; and the test methods for yield strength, tensile strength and elongation shall comply with provisions of GB/T 228.1.
Appendix A
(Normative)
Supplementary Requirements
A.1 Limited chemical composition
The purchaser shall limit the product analysis tolerance for one or more elements. A.2 Limited incidental elements
The copper, nickel, chromium, molybdenum in the microalloyed steel or other elements specified in the purchase order shall not exceed the limits specified in the purchase order. A.3 Non-metallic inclusions
The purchaser shall limit non-metallic inclusions; and the method for determining the content of non-metallic inclusions shall comply with the provisions of GB/T 10561.For vulcanized microalloyed steel, the maximum content of sulfide inclusions shall be determined through negotiation between the supplier and the purchaser.
A.4 Stress relief
When the supplier and the purchaser sides reach an agreement, the microalloyed steel shall be subjected to a cycle of stress relief treatment.
A.5 Impact test
A.5.1 The impact test method of forgings shall comply with the provisions of GB/T 229.The notch type, impact absorption energy and experimental temperature requirements shall be determined through negotiation between the supplier and the purchaser; and each group of tests contains 3 specimens.
A.5.2 The sampling location of the test specimen and the preparation of the specimen shall comply with the provisions of GB/T 2975.
A.6 Cleaning
The surface of the forgings shall be cleaned by shot peening or other suitable methods; and shall be subjected to anti-rust treatment.
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