National Standard of the People’s Republic of China
GB/T 9945-2025
Replaces GB/T 9945-2012
Hot-rolled bulb flats
(English Translation)
Issue date: 2025-06-30 Implementation date: 2026-01-01
Issued by State Administration for Market Regulation of the People's Republic of China
the Standardization Administration of the People's Republic of China
Hot-rolled bulb flats
1 Scope
This standard specifies the order information, model, dimension, shape, weight and permissible tolerance, technical requirements, inspection rules, packaging, marking and quality certificate of hot-rolled bulb flats.
This standard is applicable to the asymmetric hot-rolled bulb flats used in shipbuilding, marine engineering, bridge engineering and steel structure, etc.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions 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 222 Permissible tolerances for chemical composition of steel products
GB/T 223.5 Steel and iron - Determination of acid-soluble silicon and total silicon content - Reduced molybdosilicate spectrophotometric method
GB/T 223.9 Iron, steel and alloy - Determination of aluminum content - Chrome azurol S photometric method
GB/T 223.12 Methods for chemical analysis of iron, steel and alloy - The sodium carbonate separation-diphenyl carbazide photometric method for the determination of chromium content
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 223.16 Methods for chemical analysis of iron, steel and alloy - The chromotropic acid photometric method for the determination of titanium content
GB/T 223.19 Methods for chemical analysis of iron,steel and alloy - The neocuproine-chloroform extraction photometric method for the determination of copper content
GB/T 223.26 Iron, steel and alloy - Determination of molybdenum content - The thiocyanate spectrophotometric method
GB/T 223.40 Iron, steel and alloy - Determination of niobium content by the sulphochlorophenol S spectrophotometric method
GB/T 223.54 Iron, steel and alloy - Determination of nickel content - Flame atomic absorption spectrometric method
GB/T 223.62 Methods for chemical analysis of iron, steel and alloy - The butyl acetate extraction photometric method for the determination of phosphorus content
GB/T 223.63 Iron, steel and alloy - Determination of manganese content - Sodium (potassium) periodate spectrophotometric method
GB/T 223.69 Iron, steel and alloy - Determination of carbon contents - Gas-volumetric method after combustion in the pipe furnace
GB/T 223.72 Iron, steel and alloy - Determination of sulfur content - Gravimetric 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 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 4336 Carbon and low-alloy steel - Determination of multi-element contents - Spark discharge atomic emission spectrometric method (routine method)
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 20125 Low-alloy steel - Determination of multi-element contents - Inductively coupled plasma atomic emission spectrometric method
YB/T 081 Rule for rounding off of numerical values and judgment of testing values for technical standards of metallurgy
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
as-rolled; AR
condition of steel without any special rolling and/or heat treatment
3.2
normalizing rolling; NR
rolling process in which the final rolling deformation is carried out in the normalized temperature range, and then cooling in the air to obtain the material properties equivalent to that obtained in normalized treatment
Note: normalizing rolling is also referred to as "controlled rolling" (CR).
3.3
normalizing; N
process in which rolled steel is heated above the critical temperature (Ac3), and kept at the lower edge of austenite recrystallization temperature zone for a specified period of time, and then cooled in the air. This method improves the mechanical properties of hot rolled steel by refining grain size and uniform microstructure.
4 Order contents
Contracts or orders made based on this standard shall cover the following information:
a) number of this standard;
b) product name;
c) designation;
d) delivery condition;
e) model and length;
f) weight.
National Standard of the People’s Republic of China
GB/T 9945-2025
Replaces GB/T 9945-2012
Hot-rolled bulb flats
(English Translation)
Issue date: 2025-06-30 Implementation date: 2026-01-01
Issued by State Administration for Market Regulation of the People's Republic of China
the Standardization Administration of the People's Republic of China
Hot-rolled bulb flats
1 Scope
This standard specifies the order information, model, dimension, shape, weight and permissible tolerance, technical requirements, inspection rules, packaging, marking and quality certificate of hot-rolled bulb flats.
This standard is applicable to the asymmetric hot-rolled bulb flats used in shipbuilding, marine engineering, bridge engineering and steel structure, etc.
2 Normative references
The following documents contain requirements which, through reference in this text, constitute provisions 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 222 Permissible tolerances for chemical composition of steel products
GB/T 223.5 Steel and iron - Determination of acid-soluble silicon and total silicon content - Reduced molybdosilicate spectrophotometric method
GB/T 223.9 Iron, steel and alloy - Determination of aluminum content - Chrome azurol S photometric method
GB/T 223.12 Methods for chemical analysis of iron, steel and alloy - The sodium carbonate separation-diphenyl carbazide photometric method for the determination of chromium content
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 223.16 Methods for chemical analysis of iron, steel and alloy - The chromotropic acid photometric method for the determination of titanium content
GB/T 223.19 Methods for chemical analysis of iron,steel and alloy - The neocuproine-chloroform extraction photometric method for the determination of copper content
GB/T 223.26 Iron, steel and alloy - Determination of molybdenum content - The thiocyanate spectrophotometric method
GB/T 223.40 Iron, steel and alloy - Determination of niobium content by the sulphochlorophenol S spectrophotometric method
GB/T 223.54 Iron, steel and alloy - Determination of nickel content - Flame atomic absorption spectrometric method
GB/T 223.62 Methods for chemical analysis of iron, steel and alloy - The butyl acetate extraction photometric method for the determination of phosphorus content
GB/T 223.63 Iron, steel and alloy - Determination of manganese content - Sodium (potassium) periodate spectrophotometric method
GB/T 223.69 Iron, steel and alloy - Determination of carbon contents - Gas-volumetric method after combustion in the pipe furnace
GB/T 223.72 Iron, steel and alloy - Determination of sulfur content - Gravimetric 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 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 4336 Carbon and low-alloy steel - Determination of multi-element contents - Spark discharge atomic emission spectrometric method (routine method)
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 20125 Low-alloy steel - Determination of multi-element contents - Inductively coupled plasma atomic emission spectrometric method
YB/T 081 Rule for rounding off of numerical values and judgment of testing values for technical standards of metallurgy
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
as-rolled; AR
condition of steel without any special rolling and/or heat treatment
3.2
normalizing rolling; NR
rolling process in which the final rolling deformation is carried out in the normalized temperature range, and then cooling in the air to obtain the material properties equivalent to that obtained in normalized treatment
Note: normalizing rolling is also referred to as "controlled rolling" (CR).
3.3
normalizing; N
process in which rolled steel is heated above the critical temperature (Ac3), and kept at the lower edge of austenite recrystallization temperature zone for a specified period of time, and then cooled in the air. This method improves the mechanical properties of hot rolled steel by refining grain size and uniform microstructure.
4 Order contents
Contracts or orders made based on this standard shall cover the following information:
a) number of this standard;
b) product name;
c) designation;
d) delivery condition;
e) model and length;
f) weight.
