GB/T Translated English of Chinese Standard: GB/T NATIONAL STANDARD OF THE

Transcription

1 Translated English of Chinese Standard: GB/T GB NATIONAL STANDARD OF THE PEOPLE S REPUBLIC OF CHINA ICS H 40 GB/T Replacing GB/T Spring Steels Issued on: August 14, 2007 Implemented on: March 1, 2008 Issued by: General Administration of Quality Supervision, Inspection and Quarantine; Standardization Administration of PRC. Page 1 of 26

2 Table of Contents Foreword Scope Normative References Order Contents Dimension, Shape, Weight and Permissible Deviation Technical Requirements Test Methods Inspection Rules Packing, Marking and Quality Certificate Appendix A (Normative) Size, Appearance and Permissible Deviation of Flat Hot Rolled Bar Appendix B (Normative) 28MnSiB Technical Conditions Appendix C (Informative) Characteristic Value of 28MnSiB Page 2 of 26

3 Foreword This Standard replaces GB/T Spring Steels. Compared with GB/T , this Standard mainly has the following changes: --- Add a chapter for spring steel Range (see 1 in this Edition); --- Add a chapter for Normative References (see 2 in this Edition); --- Add a chapter for Ordering Contents (see 3 in this Edition); --- Add the uniform number code for steel designation (see 5.1 in this Edition); --- Delete three designations, such as 55Si2Mn, 55Si2MnB, 60CrMnMoA; Add the designation 55SiCrA (see Table 6 in Edition 1984; and Table 1 in this Edition); --- Adjust the Mn content of 60Si2Mn, and 60Si2MnA (see Table 6 in Edition 1984; and Table 1 in this Edition); --- Tighten some designations requirements for the sulfur and phosphorus content (see Table 6 in Edition 1984; and Table 1 in this Edition); --- Modify the provision of Smelting Method (see 3.2 in Edition 1984; and 5.2 in this Edition); --- Add the provisions of delivery state for surface treatment (see 3.3 in Edition 1984; and in this Edition); --- Re-name the name and unit symbol of mechanical properties as per GB/T (see Table 7 in Edition 1984; and Table 2 in this Edition); --- Add the provisions for mechanical property specimen blank dimension, and spring flat steel specimen (see in this Edition); --- Add the steels with diameter or thickness greater than 80mm; the provisions for sampling test after substituting forging (rolling) (see in this Edition); --- Adjust some designations index for delivery hardness (see Table 8 in Edition 1984; and Table 3 in this Edition); --- Supplement the heat treatment system for 55SiMnVB hardenability test (see in this Edition); --- Add the provision of replacing hardenability test by hardenability calculation method (see in this Edition); Page 3 of 26

4 Spring Steels 1 Scope This Standard specifies the order contents, dimension, shape, weight, allowable variation, technical requirements, test methods, test rules, packing, marking and quality certificate of hot-rolled, forged and cold drawn spring steel. This Standard is applicable to the round spring steel with diameter no larger than 100mm, square steel with side length no larger than 100mm (hereinafter referred to as steel bar), flat spring steel with thickness no larger than 40mm and spring steel wire rod with diameter no larger than 25mm [excluding the wire rod for oil hardening-tempering steel spring wire-rod (YB/T 5365)]. According to the consultation by the supplier and the purchaser, steel bar with diameter or side length greater than 100mm, flat steel with thickness 40mm and wire rod with diameter greater than 25mm can also be supplied. The designation and chemical composition specified in this Standard are also applicable to ingot steel, steel billet and their products. 2 Normative References The provisions in following documents become the provisions of this Standard through reference in this Standard. For dated references, the subsequent amendments (excluding corrigendum) or revisions do not apply to this Standard, however, parties who reach an agreement based on this Standard are encouraged to study if the latest versions of these documents are applicable. For undated references, the latest edition of the referenced document applies. GB/T 222 Permissible Tolerances for Chemical Composition of Steel Products GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Diantipyrylmethane Phosphomolybdate Gravimetric Method for the Determination of Phosphorus Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Reduced Molybdosilicate Spectrophotometric Method for the Determination of Acid-Soluble Silicon Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Ammonium Persulfate Oxidation Volumetric Method for the Determination of Page 6 of 26

5 Chromium Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy-the Ammonium Ferrous Sulfate Titration Method for the Determination of Vanadium Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy the Sodium Thiosulfate Separation Iodimetric Method for the Determination of Copper Content GB/T Methods for Chemical Analysis of Iron Steel and Alloy - The Neocuproine-Chloroform Extraction Photometric Method for the Determination of Copper Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Dimethylglyoxime Spectrophotometric Method for the Determination of Nickel Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Extraction Separation - The Dimethylglyoxime Spectrophotometric Method for the Determination of Nickel Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy; Determination of Tungsten Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Sodium Arsenite-Sodium Nitrite Titrimetric Method for the Determination of Manganese Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Reduced Molybdoantimonyl Phosphoric Acid Photometric Method for the Determination of Phosphorus Content GB/T Methods for Chemical Analysis of Iron Steel and Alloy - The Perchloric Acid Dehydration Gravimetric Method for the Determination of Silicon Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Ammonium Phosphomolybdate Volumetric Method for the Determination of Phosphorus Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Flame Atomic Absorption Spectrometric Method for the Determination of Manganese Content GB/T Methods for Chemical Analysis of Iron, Steel and Alloy - The Reducing Distillation-Methylene Blue Photometric Method for the Determination of Sulfur Content Page 7 of 26

6 GB/T 2101 General Requirements of Acceptance, Packaging, Marking, and Certification for Section Steel GB/T 2975 Steel and Steel Products - Location and Preparation of Test Pieces for Mechanical Testing (GB/T , eqv ISO 377:1997) GB/T 3078 Technical Conditions for Drawn Steel Material of High Quality Structural Steel GB/T 4336 Standard Test Method for Spark Discharge Atomic Emission Spectrometric Analysis of Carbon and Low-Alloy Steel (Routine Method) GB/T 6394 Metal-Methods for Estimating the Average Grain Size GB/T 7736 Ultrasonic Inspecting Method for Macro-Structure and Imperfection of Steel GB/T Determination of Content of Non-metallic Inclusions in Steel; Micrographic Method Using Standards Diagrams (GB/T , ISO 4967:1998, IDT) GB/T Methods for Chemical Analysis of High Carbon Chromium Bearing Steel; the Pulse Heating Inert Gas Fusion; Infra-Red Absorption Method for the Determination of Oxygen Content GB/T Steel - Determination of Microstructure GB/T Steel - Determination of Area Content of Graphite - Micrographic Method Using Diagrams GB/T Dimension, Shape, Weight and Permissible Deviation for Wire Rod GB/T Steel and Steel Products - General Technical Delivery Requirements (GB/T , eqv ISO 404:1992) 3 Order Contents The order contract or order according to this Standard shall include the following contents: a) Serial number of the standard; b) Product name; c) Designation or uniform code; d) Delivery weight (or quantity); Page 9 of 26

7 e) Dimension and shape; f) Delivery state; g) Non-metallic inclusion (the requirements is in accordance with 5.7); h) Special requirement (the requirements is in accordance with 5.10). 4 Dimension, Shape, Weight and Permissible Deviation 4.1 Hot rolled rod The dimension, shape and allowable variation of hot rolled rod shall meet the relevant provisions in GB/T 702 and the specific requirements shall be noted in contract. 4.2 Forged bar The dimension, shape and allowable variation of forged bar shall meet the relevant provisions in GB/T 908 and the specific requirements shall be noted in contract. 4.3 Wire rod The dimension and allowable variation of wire rod shall meet the relevant provisions in GB/T and the specific requirements shall be noted in contract. 4.4 Cold-drawn bars The dimension, shape and allowable variation of cold-drawn bars shall meet the relevant provisions in GB/T 905 and the specific requirements shall be noted in contract. 4.5 Hot-rolled flats The dimension, shape and allowable variation of hot-rolled flats shall meet the relevant provisions in Appendix A and the specific requirements shall be noted in contract. 4.6 Weight Deliver the steel according to actual weight. 5 Technical Requirements 5.1 Designation and chemical composition Page 10 of 26

8 5.6.2 The level of acid leaching macrostructure shall in accordance with specifications specified in Table 4. Table 4 Macrostructure Qualification Grade Ingot Case Segregation Centre Porosity Common Porosity Qualification grade, no larger than If the supplier could assure that the macroscopic test is qualified, ultrasonic process or other methods of nondestructive inspection could be used to replace acid leaching macroscopic test Fracture inspection shall be carried out for heat treated and delivered silicon-manganese spring steels and fractures shall have no visible graphite carbon. 5.7 Non-metallic inclusion As required by the demander and indicated in the contract, non-metallic inclusion of the steel can be inspected; the qualification grade shall meet specifications in accordance with those specified in Table The non-metallic inclusion shall conform to the specifications in GB/T and the result shall be represented as the serious one. Table 5 Type of non-metallic inclusion Non-Metallic Inclusion Qualification Grade Qualification Grade, No Larger than Thin Coarse A B C D Note: if the demander has requirements for impurities and DS impurities, the requirements shall be noted in the contract and the qualification grade shall be negotiated by the supply and demand parties. 5.8 Decarburized layer Depth of the total steel decarburized layer (full decarburization + partly decarburization) of each side shall not be more than the specification in Table 6 (broadside inspection of flat steel decarburized layer) The surface of delivered steel with excorticate or polished steel shall not have decarburized layer. Page 15 of 26

9 Table 6 Total Surface Decarburized Layer Depth of Each Side The total decarburized layer depth shall not more than the diameter Nominal or thickness by a percentage of / % diameter Hot-rolling material Designation length or Square Forged Cold drawn thickness/ Round steel, steel, flat material material mm rod bundle steel Silicon spring > 8~ steel Negotiated by > both parties Other spring steel > Surface quality The surface of hot-rolled or forged steels shall be free from any cracks, folds, scars, foreign substances, lamination and pressed oxidized iron scales. The local defects of the steel shall be cleared off, in which detrimental impacts shall not be caused to the steel; and after clearing, the steel shall not be less than the smallest allowable size and the cleared width shall be not be less than 5 times of the cleared depth. It s allowable that the fine scratches or press marks are not more than the half of the nominal dimension tolerance calculated according to the actual size The surface of cold-drawn circular steel shall conform to specifications in GB/T The surface of delivered excorticated or polish steel shall be smooth, bright and clean, and shall not have external defects such as cracks, hair cracks, folds, scratches, concaves, scars, and rust and oxide skins. Exceptional shadow scratches, spiracles or lubricant marks the depth of which are not more than half of the nominal diameter are allowed to exist Special requirement As required by the demander, agreed by the supply and demand parties and noted in the contract, the following specialized steels could be supplied. a) Restrict the residual element content; b) Specify the hardenability requirement (except for 55SiMnVB steel); c) Examine microscopic structure of the steel; d) Examine grain size; e) Examine oxygen content; Page 16 of 26

10 and acceptance for any inspection item specified in this Standard or the contract. 7.2 Batching rules Steels shall be inspected and accepted in batches, each batch shall consists of steels of the same designation, the same furnace number, the same processing method, the same size, the same heat treating furnace times (or system) and the same delivery state. 7.3 Sampling quantity and sampling location Sampling quantity and sampling location of each batch of steels shall be in accordance with those specified in Table Re-inspection and decision rules Re-inspection and decision rules of steels shall be implemented according to GB/T If the supplier could that if the steel is qualified, the inspection results of oxygen content, mechanical property, macro-structure, jominy hardenability and non-metallic inclusion of steels or steel billets with the same furnace number, billets replacing steels or the big one being replaced by the smaller one is allowed. 8 Packing, Marking and Quality Certificate The package, marks and quality specifications of steel shall meet the provisions specified in GB/T Page 18 of 26

11 Table A.5 Tortuosity Factor of Each Meter of the Flat Steel Flat steel thickness Bend direction General precision Higher precision Not more than < 7 Side bend Flat bend Side bend Flat bend Page 23 of 26

12 B.3.2 According to negotiation between the supply and demand parties, hardenability calculation is allowed to replace the hardenability test. The hardenability calculation method shall be negotiated and then determined the supply and demand parties. B.4 Other technical requirements, test methods, inspection rules, packing, mark and quality certificate Other technical requirements, test methods, inspection rules, packing, mark and quality certificate shall be implemented in accordance with the text of this Standard. Page 25 of 26