Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 15712-2008 Microalloyed medium carbon steels.
The following main changes have been made with respect to GB/T 15712-2008:
——The classification of steel by microstructure has been added;
——Six designations including F70VS, F38MnSiNS, F48MnV, F37MnSiVS, F41MnSiV, F25Mn2CrVS and related requirements have been added;
——The silicon content of some designations is adjusted: the silicon content in F35VS, F40VS and F45VS is adjusted from 0.20%~0.40% to 0.15%~0.35%, and that of F30MnVS and F38MnVS is adjusted from ≤ 0.80% to 0.30%~0.80%;
——The range of carbon content of F38MnVS is adjusted from 0.34%~0.41% to 0.35%~0.42%;
——The requirements of Mo ≤ 0.05% is added;
——The tolerance of chemical composition of finished products of residual elements Ni, Cu, Mo, Nb and Ti is deleted;
——The recommended calculation equation of carbon equivalent is added;
——The requirements for macroscopic examination are stricter;
——The requirement of decarburized layer are stricter;
——Grain size is added as the agreement requirement;
——The “surface quality may meet the requirements of GB/T 28300” is added;
——The requirement that “inspection documents may be provided according to GB/T 18253” is added.
This standard is a redraft based on modified adoption of ISO 11692:1994 Ferritic-pearlitic engineering steels for precipitation hardening from hot-working temperatures.
For convenience of comparison, this standard provides a comparison list of clauses of this standard and ISO 11692:1994, as shown in Annex A.
According to the actual situation of China, modifications have been made in adoption of ISO 11692:1994: These technical differences have been made in this standard and marked with a perpendicular single line (|) at the page margin of relevant clauses. The technical differences, together with their reasons are given in Annex B for reference.
For the convenience of application, the following editorial modifications are made in this standard:
——The standard name is changed from "Ferritic-pearlitic engineering steels for precipitation hardening from hot-working temperatures" to "Microalloyed medium carbon steels".
This standard was proposed by China Iron and Steel Industry Association.
This standard is under the jurisdiction of the National Technical Committee on Iron and Steel of Standardization Administration of China (SAC/TC 183).
The previous editions of this standard are as follows:
——GB/T 15712-1995, GB/T 15712-2008.
Microalloyed medium carbon steels
1 Scope
This standard specifies the terms and definitions, classification, ordering, shape, dimensions and tolerances, technical requirements, test methods, inspection rules, packaging, marking and quality certificates of microalloyed medium carbon steels.
This standard is applicable to hot rolled steel and bright steel of microalloyed medium carbon steels (hereinafter referred to as the steel).
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 223.5 Steel and iron—Determination of acid-soluble silicon and total silicon content—Reduced molybdosilicate spectrophotometric method (GB/T 223.5—2008, ISO 4829-1:1986, ISO 4829-2;1988, MOD)
GB/T 223.11 Iron, steel and alloy—Determination of chromium content—Visual titration or potentiometric titration method (GB/T 223.11-2008, ISO 4937:1986, MOD)
GB/T 223.16 Methods for chemical analysis of iron, steel and alloy—The chromotropic acid photometric method for the determination of titanium content
GB/T 223.18 Methods for chemical analysis of iron, steel and alloy—The sodium thiosulfate separation iodimetric method for the determination of cupper content
GB/T 223.23 Iron, steel and alloy—Determination of nickel content—The dimethylglyoxime spectrophotometric method (GB/T 223.23-2008, ISO 4939:1984, MOD)
GB/T 223.26 Iron, steel and alloy—Determination of molybdenum content—The thiocyanate spectrophotometric method
GB/T 223.37 Methods for chemical analysis of iron, steel and alloy—The indophenol blue photometric methods for the determination of nitrogen content after distillation separation
GB/T 223.40 Iron, steel and alloy—Determination of niobium content by the sulphochlorophenol S spectrophotometric method
GB/T 223.58 Methods for chemical analysis of iron, steel and alloy—The sodium arsenite-sodium nitrite titrimetric method for the determination of manganese content
GB/T 223.59 Iron, steel and alloy—Determination of phosphorus content—Bismuth phosphomolybdate blue spectrophotometric method and antimony phosphomolybdate blue spectrophotometric method
GB/T 223.68 Methods for chemical analysis of iron, steel and alloy—The potassium iodate titration method after combustion in the pipe furnace for the determination of sulfur content (GB/T 223.68-1997, ISO 671:1982, MOD)
GB/T 223.69 Iron, steel and alloy—Determination of carbon contents—Gas-volumetric method after combustion in the pipe furnace
GB/T 223.76 Methods for chemical analysis iron, steel and alloy—The flame atomic absorption spectrometric method for the determination of vanadium content (GB/T 223.76-1994, ISO 9647:1989, MOD)
GB/T 223.78 Methods for chemical analysis of iron, steel and alloy—Curcumin spectrophotometric method for the determination of boron content (GB/T 223.78-2000, ISO 10153:1997, IDT)
GB/T 224-2008 Determination of depth of decarburization of steels (ISO 3887:2003, MOD))
GB/T 226 Test method for macrostructure and defect of steel by etching
GB/T 228.1 Metallic materials—Tensile testing—Part 1: Method of test at room temperature (GB/T 228.1-2010, ISO 6892-1:2009, MOD)
GB/T 229 Metallic materials—Charpy pendulum impact test method (GB/T 229-2007, ISO 148-1:2006, MOD)
GB/T 231.1 Metallic materials—Brinell hardness test—Part 1: Test method (GB/T 231.1-2009, ISO 6506-1:2005, MOD)
GB/T 702-2008 Hot-rolled steel bars—Dimensions, shape, weight and tolerances (ISO 1035-1:1980, ISO 1035-2:1980, ISO 1035-4:1982, MOD)
GB/T 1979 Standard diagrams for macrostructure and defect of structural steels
GB/T 2101 General requirement of acceptance, packaging, marking and certification for section steel
GB/T 2975 Steel and steel products—Location and preparation of samples and test pieces for mechanical testing (GB/T 2975-1998, eqv ISO 377:1997)
GB/T 3207-2008 Bright steel
GB/T 4162 Forged and rolled steel bars—Method for ultrasonic testing
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 10561-2005 Steel—Determination of content of nonmetallic inclusions—Micrographic method using standards diagrams (ISO 4967:1998, IDT)
GB/T 13298 Inspection methods of microstructure for metals
GB/T 13299 Steel—Determination of microstructure
GB/T 13304.1 Steels classification—Part 1: Classification of according to chemical composition (GB/T 13304.1-2008, ISO 4948-1:1982)
GB/T 15574 Steel products—Vocabulary (GB/T 15574-2016, ISO 6929:2013, MOD)
GB/T 17505 Steel and steel products—General technical delivery requirements (GB/T 17505-2016, ISO 404:2013, MOD)
GB/T 18253 Steel and steel products—Types of inspection documents (GB/T 18253-2002, ISO 10474:1991, MOD)
GB/T 20066 Steel and iron—Sampling and preparation of samples for the determination of chemical composition (GB/T 20066-2006, ISO 14284: 1996, IDT)
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 20123-2006, ISO 15350:2000, IDT)
GB/T 20124 Steel and iron—Determination of nitrogen content—Thermal conductimetric method after fusion in a current of inert gas (routine method) (GB/T 20124-2006, ISO 15351:1999, IDT)
GB/T 20125 Low-alloy steel—Determination of multi-element contents—Inductively coupled plasma atomic emission spectrometric method
GB/T 28300 Surface quality classes for hot-rolled bars and rods technical delivery conditions
3 Terms and definitions
For the purposes of this document, the terms and definitions specified in GB/T 15574 and GB/T 13304.1 as well as the following apply.
3.1
microalloyed medium carbon steels
high-quality or special-quality structural steel which can achieve or approach the mechanical properties of quenched and tempered steel by means of strengthening and toughening methods such as microalloying, controlled rolling (forging) and controlled cooling
4 Classification
4.1 Steels are classified, by microstructure, as
a) ferrite-pearlite steel;
b) bainitic steel.
4.2 Steels are classified, by the processing methods used, as:
a) steel for direct cutting (UC);
b) steel for hot press processing (UHP);
5 Ordering
Order contracts made based on this standard shall cover the following:
a) No. of this standard;
b) Designation and chemical composition;
c) Dimension;
d) Weight;
e) Processing methods used;
f) Delivery state;
g) Accuracy level;
h) Items negotiated by the supplier and the buyer in this standard;
i) Other special requirements.
6 Dimensions, shape and tolerances
6.1 The dimensions, shape and tolerances of hot rolled steel shall comply with GB/T 702-2008, and the dimensional accuracy requirements shall be indicated in the contract; if not specified, they shall be executed according to Group 2 accuracy.
6.2 The dimensions, shape and tolerances of bright steel shall comply with GB/T 3207-2008, and the dimensional accuracy requirements shall be indicated in the contract; if not specified, it shall be executed according to Group 11 accuracy.
7 Technical requirements
7.1 Designation and chemical composition
7.1.1 The designation and chemical composition (melting analysis) of steel for hot press processing shall meet those specified in Table 1. The chemical composition of steel for direct cutting shall generally meet the requirements of Table 1. However, in order to ensure the mechanical properties are qualified, it may exceed the scope of chemical composition specified in Table 1 after negotiation between the supplier and the buyer and indicated in the contract.
7.1.2 The tolerances of chemical composition of the steel shall meet those specified in Table 2.
7.1.3 According to the requirements of the buyer, the carbon equivalent requirements may be specified through negotiation between the supplier and the buyer. See Equation (1) for the recommended calculation equation of carbon equivalent:
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Classification
5 Ordering
6 Dimensions, shape and tolerances
7 Technical requirements
8 Test methods
9 Inspection rules
10 Packaging, marking and quality certificate
Annex A (Informative) Comparison of clause numbers of this standard and those of ISO 11692:
Annex B (Informative) Technical differences between this standard and ISO 11692:1994 and their reasons
Annex C (Informative) Comparison between designation of this standard and designation of ISO 11692:
Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 15712-2008 Microalloyed medium carbon steels.
The following main changes have been made with respect to GB/T 15712-2008:
——The classification of steel by microstructure has been added;
——Six designations including F70VS, F38MnSiNS, F48MnV, F37MnSiVS, F41MnSiV, F25Mn2CrVS and related requirements have been added;
——The silicon content of some designations is adjusted: the silicon content in F35VS, F40VS and F45VS is adjusted from 0.20%~0.40% to 0.15%~0.35%, and that of F30MnVS and F38MnVS is adjusted from ≤ 0.80% to 0.30%~0.80%;
——The range of carbon content of F38MnVS is adjusted from 0.34%~0.41% to 0.35%~0.42%;
——The requirements of Mo ≤ 0.05% is added;
——The tolerance of chemical composition of finished products of residual elements Ni, Cu, Mo, Nb and Ti is deleted;
——The recommended calculation equation of carbon equivalent is added;
——The requirements for macroscopic examination are stricter;
——The requirement of decarburized layer are stricter;
——Grain size is added as the agreement requirement;
——The “surface quality may meet the requirements of GB/T 28300” is added;
——The requirement that “inspection documents may be provided according to GB/T 18253” is added.
This standard is a redraft based on modified adoption of ISO 11692:1994 Ferritic-pearlitic engineering steels for precipitation hardening from hot-working temperatures.
For convenience of comparison, this standard provides a comparison list of clauses of this standard and ISO 11692:1994, as shown in Annex A.
According to the actual situation of China, modifications have been made in adoption of ISO 11692:1994: These technical differences have been made in this standard and marked with a perpendicular single line (|) at the page margin of relevant clauses. The technical differences, together with their reasons are given in Annex B for reference.
For the convenience of application, the following editorial modifications are made in this standard:
——The standard name is changed from "Ferritic-pearlitic engineering steels for precipitation hardening from hot-working temperatures" to "Microalloyed medium carbon steels".
This standard was proposed by China Iron and Steel Industry Association.
This standard is under the jurisdiction of the National Technical Committee on Iron and Steel of Standardization Administration of China (SAC/TC 183).
The previous editions of this standard are as follows:
——GB/T 15712-1995, GB/T 15712-2008.
Microalloyed medium carbon steels
1 Scope
This standard specifies the terms and definitions, classification, ordering, shape, dimensions and tolerances, technical requirements, test methods, inspection rules, packaging, marking and quality certificates of microalloyed medium carbon steels.
This standard is applicable to hot rolled steel and bright steel of microalloyed medium carbon steels (hereinafter referred to as the steel).
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 223.5 Steel and iron—Determination of acid-soluble silicon and total silicon content—Reduced molybdosilicate spectrophotometric method (GB/T 223.5—2008, ISO 4829-1:1986, ISO 4829-2;1988, MOD)
GB/T 223.11 Iron, steel and alloy—Determination of chromium content—Visual titration or potentiometric titration method (GB/T 223.11-2008, ISO 4937:1986, MOD)
GB/T 223.16 Methods for chemical analysis of iron, steel and alloy—The chromotropic acid photometric method for the determination of titanium content
GB/T 223.18 Methods for chemical analysis of iron, steel and alloy—The sodium thiosulfate separation iodimetric method for the determination of cupper content
GB/T 223.23 Iron, steel and alloy—Determination of nickel content—The dimethylglyoxime spectrophotometric method (GB/T 223.23-2008, ISO 4939:1984, MOD)
GB/T 223.26 Iron, steel and alloy—Determination of molybdenum content—The thiocyanate spectrophotometric method
GB/T 223.37 Methods for chemical analysis of iron, steel and alloy—The indophenol blue photometric methods for the determination of nitrogen content after distillation separation
GB/T 223.40 Iron, steel and alloy—Determination of niobium content by the sulphochlorophenol S spectrophotometric method
GB/T 223.58 Methods for chemical analysis of iron, steel and alloy—The sodium arsenite-sodium nitrite titrimetric method for the determination of manganese content
GB/T 223.59 Iron, steel and alloy—Determination of phosphorus content—Bismuth phosphomolybdate blue spectrophotometric method and antimony phosphomolybdate blue spectrophotometric method
GB/T 223.68 Methods for chemical analysis of iron, steel and alloy—The potassium iodate titration method after combustion in the pipe furnace for the determination of sulfur content (GB/T 223.68-1997, ISO 671:1982, MOD)
GB/T 223.69 Iron, steel and alloy—Determination of carbon contents—Gas-volumetric method after combustion in the pipe furnace
GB/T 223.76 Methods for chemical analysis iron, steel and alloy—The flame atomic absorption spectrometric method for the determination of vanadium content (GB/T 223.76-1994, ISO 9647:1989, MOD)
GB/T 223.78 Methods for chemical analysis of iron, steel and alloy—Curcumin spectrophotometric method for the determination of boron content (GB/T 223.78-2000, ISO 10153:1997, IDT)
GB/T 224-2008 Determination of depth of decarburization of steels (ISO 3887:2003, MOD))
GB/T 226 Test method for macrostructure and defect of steel by etching
GB/T 228.1 Metallic materials—Tensile testing—Part 1: Method of test at room temperature (GB/T 228.1-2010, ISO 6892-1:2009, MOD)
GB/T 229 Metallic materials—Charpy pendulum impact test method (GB/T 229-2007, ISO 148-1:2006, MOD)
GB/T 231.1 Metallic materials—Brinell hardness test—Part 1: Test method (GB/T 231.1-2009, ISO 6506-1:2005, MOD)
GB/T 702-2008 Hot-rolled steel bars—Dimensions, shape, weight and tolerances (ISO 1035-1:1980, ISO 1035-2:1980, ISO 1035-4:1982, MOD)
GB/T 1979 Standard diagrams for macrostructure and defect of structural steels
GB/T 2101 General requirement of acceptance, packaging, marking and certification for section steel
GB/T 2975 Steel and steel products—Location and preparation of samples and test pieces for mechanical testing (GB/T 2975-1998, eqv ISO 377:1997)
GB/T 3207-2008 Bright steel
GB/T 4162 Forged and rolled steel bars—Method for ultrasonic testing
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 10561-2005 Steel—Determination of content of nonmetallic inclusions—Micrographic method using standards diagrams (ISO 4967:1998, IDT)
GB/T 13298 Inspection methods of microstructure for metals
GB/T 13299 Steel—Determination of microstructure
GB/T 13304.1 Steels classification—Part 1: Classification of according to chemical composition (GB/T 13304.1-2008, ISO 4948-1:1982)
GB/T 15574 Steel products—Vocabulary (GB/T 15574-2016, ISO 6929:2013, MOD)
GB/T 17505 Steel and steel products—General technical delivery requirements (GB/T 17505-2016, ISO 404:2013, MOD)
GB/T 18253 Steel and steel products—Types of inspection documents (GB/T 18253-2002, ISO 10474:1991, MOD)
GB/T 20066 Steel and iron—Sampling and preparation of samples for the determination of chemical composition (GB/T 20066-2006, ISO 14284: 1996, IDT)
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 20123-2006, ISO 15350:2000, IDT)
GB/T 20124 Steel and iron—Determination of nitrogen content—Thermal conductimetric method after fusion in a current of inert gas (routine method) (GB/T 20124-2006, ISO 15351:1999, IDT)
GB/T 20125 Low-alloy steel—Determination of multi-element contents—Inductively coupled plasma atomic emission spectrometric method
GB/T 28300 Surface quality classes for hot-rolled bars and rods technical delivery conditions
3 Terms and definitions
For the purposes of this document, the terms and definitions specified in GB/T 15574 and GB/T 13304.1 as well as the following apply.
3.1
microalloyed medium carbon steels
high-quality or special-quality structural steel which can achieve or approach the mechanical properties of quenched and tempered steel by means of strengthening and toughening methods such as microalloying, controlled rolling (forging) and controlled cooling
4 Classification
4.1 Steels are classified, by microstructure, as
a) ferrite-pearlite steel;
b) bainitic steel.
4.2 Steels are classified, by the processing methods used, as:
a) steel for direct cutting (UC);
b) steel for hot press processing (UHP);
5 Ordering
Order contracts made based on this standard shall cover the following:
a) No. of this standard;
b) Designation and chemical composition;
c) Dimension;
d) Weight;
e) Processing methods used;
f) Delivery state;
g) Accuracy level;
h) Items negotiated by the supplier and the buyer in this standard;
i) Other special requirements.
6 Dimensions, shape and tolerances
6.1 The dimensions, shape and tolerances of hot rolled steel shall comply with GB/T 702-2008, and the dimensional accuracy requirements shall be indicated in the contract; if not specified, they shall be executed according to Group 2 accuracy.
6.2 The dimensions, shape and tolerances of bright steel shall comply with GB/T 3207-2008, and the dimensional accuracy requirements shall be indicated in the contract; if not specified, it shall be executed according to Group 11 accuracy.
7 Technical requirements
7.1 Designation and chemical composition
7.1.1 The designation and chemical composition (melting analysis) of steel for hot press processing shall meet those specified in Table 1. The chemical composition of steel for direct cutting shall generally meet the requirements of Table 1. However, in order to ensure the mechanical properties are qualified, it may exceed the scope of chemical composition specified in Table 1 after negotiation between the supplier and the buyer and indicated in the contract.
7.1.2 The tolerances of chemical composition of the steel shall meet those specified in Table 2.
7.1.3 According to the requirements of the buyer, the carbon equivalent requirements may be specified through negotiation between the supplier and the buyer. See Equation (1) for the recommended calculation equation of carbon equivalent:
Contents of GB/T 15712-2016
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Classification
5 Ordering
6 Dimensions, shape and tolerances
7 Technical requirements
8 Test methods
9 Inspection rules
10 Packaging, marking and quality certificate
Annex A (Informative) Comparison of clause numbers of this standard and those of ISO 11692:
Annex B (Informative) Technical differences between this standard and ISO 11692:1994 and their reasons
Annex C (Informative) Comparison between designation of this standard and designation of ISO 11692:
