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This standard is developed in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 1591-2008 High Strength Low Alloy Structural Steels. In addition to a number of editorial changes, the following technical changes have been made with respect to GB/T 1591-2008:
——It is specified that the chemical composition in this standard is also applicable to billet (see Chapter 1; Chapter 1 in 2008 edition);
——Definitions of “thermomechanical processed” and “normalizing rolling” are revised, and terms and definitions of “as-rolled” and “normalized” are added (see Chapter 3; Chapter 3 in 2008 edition);
——Designation expression method is revised (see Chapter 4; Chapter 4 in 2008 edition);
——Order contents are added (see Chapter 5);
——Requirements for dimension, shape, weight and permissible deviation are defined (see Chapter 6; Chapter 5 in 2008 edition);
——Q345 steel grade and relevant requirements are replaced by Q355 steel grade (see Chapter 7 and 9.2; Chapter 6 and 8.2 in 2008 edition);
——Chemical composition of each designation is specified according to different delivery states, and the content of refined grain elements is revised (see 7.1; 6.1 in 2008 edition);
——Mechanical property of each designation is specified according to different delivery states, and the lower yield strength is revised as the upper yield strength, with the index increased by 10~15MPa correspondingly (see 7.4.1 and 7.4.2; 6.4.1 and 6.4.2 in 2008 edition);
——Surface quality requirements for steels are detailed (see 7.5; 6.5 in 2008 edition);
——Test methods and inspection rules are revised, and sampling position for impulse test is specified (see Chapters 8 and 9; Chapters 7 and 8 in 2008 edition);
——Comparison of designations between this standard and foreign standard is added (see Annex A).
This standard was proposed by China Iron and Steel 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 standard replaced by this standard are as follows:
——GB1591-1979, GB1591-1988, GB/T 1591-1994 and GB/T 1591-2008.
High Strength Low Alloy Structural Steels
1 Scope
This standard specifies the designation expression methods, order contents, dimension, shape, weight, technical requirements, test methods, inspection rules, packaging, marking and quality certificate of high strength low alloy structural steels.
This standard is applicable to plates, strips, sections, bars, etc. of high strength low alloy structural steels used for general structures and works. Its chemical composition is also applicable to billets.
2 Normative References
The following documents are indispensable for the application of this standard. 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 223.3 Methods for Chemical Analysis of Iron, Steel and Alloy - the Diantipyrylmethane Phosphomolybdate Gravimetric Method for the Determination of Phosphorus Content
GB/T 223.9 Iron, Steel and Alloy - Determination of Aluminum Content - Chrom Azurol S Photometric Method
GB/T 223.11 Iron Steel and Alloy - Determination of Chromium Content - Visual Titration or Potentiometric Titration Method
GB/T 223.14 Methods for Chemical Analysis of Iron, Steel and Alloy -the N-benzoy-N-phenylhydroxylamine Extraction Photometric Method for the Determination of Vanadium Content
GB/T 223.17 Methods for Chemical Analysis of Iron, Steel and Alloy - the Diantipyrylmethane 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 Copper Content
GB/T 223.23 Iron Steel and Alloy - Determination of Nickel Content - the Dimethylglyoxime Spectrophotometric Method
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 Indophenal Blue Photometric Methods for the Determination of Nitrogen Content after Distillation Separation
GB/T 223.40 Iron Steel and Alloy - Detetmination of Niobium Content by the Sulphochlorophenol S Spectrophotometric Method
GB/T 223.60 Methods for Chemical Analysis of Iron, Steel and Alloy - the Perchloric Acid Dehydration Gravimetric Method for the Determination of Silicon Content
GB/T 223.63 Methods for Chemical Analysis of Iron, Steel and Alloy - the Sodium (Potassium) Periodate Photometric Method for the Determination of Manganese Content
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 223.69 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 of Iron, Steel and Alloy - the Flame Atomic Absorption Spectrometric Method for the Determination of Vanadium Content
GB/T 223.78 Methods for Chemical Analysis of Iron, Steel and Alloy - Curcumin Spectrophotometric Method for the Determination of Boron Content
GB/T 223.79 Iron and Steel - Determination of Multi-element Contents - X-ray Fluorescence Spectrometry (Routine Method)
GB/T 223.84 Steel and Alloy - Determination of Titanium Content - Diantipyrylmethane Spectrophotometric Method
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 232 Metallic Materials - Bend Test
GB/T 247 General Rule of Package, Mark and Certification for Steel Plates (Sheets) and Strips
GB/T 702 Hot-rolled Steel Bars - Dimensions, Shape, Weight and Tolerances
GB/T 706 Hot Rolled Section Steel
GB/T 709 Dimension, Shape, Weight and Tolerances for Hot-rolled Steel Plates and Sheets
GB/T 2101 General Requirement of Acceptance Packaging, Marking and Certification for Section Steel
GB/T 2975-2018 Steel and Steel Products - Location and Preparation of Test Pieces for Mechanical Testing
GB/T 4336 Carbon and Low-alloy Steel - Determination of Multi-element Contents - Spark Discharge Atomic Emission Spectrometric Method (Routine Method)
GB/T 5313 Steel Plate with Through-thickness Characteristics
GB/T 8170 Rules of Rounding off for Numerical Values & Expression and Judgment of Limiting Values
GB/T 11263 Hot-rolled H and Cut T Section Steel
GB/T 14977 General Requirement for Surface Condition of Hot-rolled Steel Plates
GB/T 17505 Steel and Steel Products: General Technical Delivery Requirements
GB/T 20066 Steel and Iron - Sampling and Preparation of Samples for the Determination of Chemical Composition
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 (Routine Method)
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
YB/T 4427 General Requirements for Surface Condition of Hot-rolled Sections
3 Terms and Definitions
For the purposes of this standard, the following terms and definitions apply.
3.1
As-rolled; AR or WAR
state of steel without any special rolling and/or thermal treatment
3.2
normalized
N
thermal treatment process for steel being heated to a proper temperature above the temperature of a phase transformation point and then cooled in air to below the temperature of this phase transformation point
3.3
normalizing rolling
+N
rolling process enabling the steel to reach normalized state with final deformation realized through rolling within certain temperature range and to meet the specified mechanical properties after being normalized
Note: normalizing rolling is also referred to as "controlled rolling" in some publications.
3.4
thermomechanical processed
M
rolling process of steel with final deformation realized within certain temperature range, thus ensuring that the steel is provided with properties which cannot be obtained through thermal treatment only
Notes:
1 Thermoforming which may reduce the strength steel, or post-weld thermal treatment at a temperatures above 580°C should not be applied. According to the relevant technical specifications, flame straightening is allowed.
2 Thermomechanical processing may include a process of increasing the cooling rate in tempered or non-tempered state; tempering includes self tempering but not includes direct quenching and quenching + tempering.
3 It is also referred to as TMCP (thermomechanical control process), or as “controlled rolling” in in some publications.
4 Designation Expression Methods
4.1 Steel designation is composed of four parts: Q (the Chinese phonetic alphabet representing yield strength); the specified minimum yield strength; the delivery state code; quality grade symbol (B, C, D, E and F).
Notes:
1 Where the delivery state is as-rolled, the delivery state code AR or WAR may be omitted; where the delivery state is normalized or normalizing rolling, the delivery state code is indicated by N.
2 Q+ the specified minimum upper yield strength value + delivery state code, referred to as “steel grade”.
Example: Q355ND. Where,
Q——the Chinese phonetic alphabet representing yield strength;
355——the specified minimum upper yield strength, MPa;
N——the delivery state of normalized or normalizing rolling;
D——the quality grade of Grade D.
4.2 Where the purchaser asks the steel plate to be provided with through-thickness property, symbol representing the through-thickness property grade (Z direction) shall be added after the above-mentioned designation, e.g. Q355NDZ25.
5 Order Contents
5.1 For the purpose of this standard, the order contract or order form shall include the following contents:
a) No. of this standard;
b) Product type;
c) Steel designation (steel grade + quality grade);
d) Dimension, shape and permissible deviation (see Chapter 6);
e) Delivery weight (or quantity);
f) All selected contents as required (see 5.2).
5.2 For the purpose of this standard, the following contents may be selected for order through negotiation between the supplier and the purchaser as indicated in the contract. If not specified by the purchaser upon inquiry and order, products shall be suppled according to 5.1.
a) Carbon equivalent value and welding crack susceptibility index (Pcm) (see 7.1.3, Table 6);
b) Added alloying elements and their contents (see 7.1.6, Tables 1, 3 and 5);
c) The lower limit of chemical composition upon supplying commercial billet (see 7.1.8);
d) Analysis of finished products (see 7.1.9);
e) Smelting method (see 7.2);
f) Temperature and sampling direction of impact test (see Table 11);
g) Bending test (see Section 7.4.3);
h) Through-thickness property of steel (see 7.1.7, 7.4.1.4 and 9.2.3);
i) Surface quality (see 7.5.1.5, 7.5.2.4, 7.5.3.2 and 7.5.4.2);
g) Non-destructive testing (see 7.6);
k) Sampling position for impact specimen (see 8.3).
6 Dimension, Shape and Weight
6.1 The dimension, shape, weight and permissible deviation of as-rolled steel bars shall meet the relevant requirements of GB/T 702, and the specific requirements shall be indicated in the contract.
6.2 The dimension, shape, weight and permissible deviation of as-rolled section steel shall meet the relevant requirements of GB/T 706, and the specific requirements shall be indicated in the contract.
6.3 The dimension, shape, weight and permissible deviation of as-rolled steel plates and sheets shall meet the relevant requirements of GB/T 709, and the specific requirements shall be indicated in the contract.
6.4 The dimension, shape, weight and permissible deviation of as-rolled H and Cut T section steel shall meet the relevant requirements of GB/T 11263.
6.5 Steels with other dimensions, shapes, weight and permissible deviations may also be supplied as agreed by the supplier and the purchaser through negotiation.
Foreword i
1 Scope
2 Normative References
3 Terms and Definitions
4 Designation Expression Methods
5 Order Contents
6 Dimension, Shape and Weight
7 Technical Requirements
8 Test Methods
9 Inspection Rules
10 Packaging, Marking and Quality Certificate
Annex A (Informative) Comparison of Designations between Domestic and Foreign Standards
