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GB/T 20564 consists of the following nine parts under the general title Continuously cold rolled high strength steel sheet and strip for automobile:
——Part 1: Bake hardening steel;
——Part 2: Dual phase steel;
——Part 3: High strength interstitial free steel;
——Part 4: High strength low alloy steel;
——Part 5: Isotropic steel;
——Part 6: Transformation induced plasticity steel;
——Part 7: Martensitic steels;
——Part 8: Complex phase steel;
——Part 9: Quenching and partitioning steel;
This part is Part 9 of GB/T 20564.
This part is developed in accordance with the rules given in GB/T 1.1-2009.
This part was proposed by China Iron and Steel Association.
This standard is under the jurisdiction of the Technical Committee on Steel of Standardization Committee of China (SAC/TC 183).
Continuously cold rolled high strength steel sheet and strip for automobile — Part 9: Quenching and partitioning steel
1 Scope
This part of GB/T 20564 specifies the term and definition, classification and code, order information, dimension, shape, weight, technical requirements, test methods, inspection rules, packaging, marking and quality certificate of quenching and partitioning high strength steel sheets and strips.
This part is applicable to steel sheets and strips with a thickness of 0.8mm~2.5mm, which are mainly used for manufacturing automobile structural members and reinforcing members.
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 222 Permissible tolerances for chemical composition of steel products
GB/T 223.4 Alloyed steel — Determination of manganese content — Potentiometric or visual titration method
GB/T 223.8 Methods for chemical analysis of iron, steel and alloy — The sodium fluoride separation — EDTA titration method for the determination of aluminium content
GB/T 223.9 Iron, steel and alloy — Determination of aluminum content — Chrome azurol S photometric method
GB/T 223.11 Iron steel and alloy — Determination of chromium content — Visual titration or potentiometric titration method
GB/T 223.23 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 223.40 Iron, steel and alloy — Determination of niobium content by the sulphochlorophenol S spectrophotometric method
GB/T 223.53 Methods for chemical analysis of iron, steel and alloy — Flame atomic absorption spectrometric method for the determination of copper 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 223.60 Methods for chemical analysis of iron, steel and alloy — 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 223.67 Iron steel and alloy — Determination of sulfur content — Methylene 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 223.69 Iron, steel and alloy — Determination of carbon contents — Gas-volumetric method after combustion in the pipe furnace
GB/T 223.71 Methods for chemical analysis of iron, steel and alloy — The gravimetric method after combustion in the pipe furnace for the determination of carbon content
GB/T 228.1-2010 Metallic materials — Tensile testing — Part 1: Method of test at room temperature
GB/T 247 General rule of package, mark and certification for steel plates(sheets) and strips
GB/T 708 Dimension, shape, weight and tolerance for cold-rolled steel strip and sheet
GB/T 2523 Measuring method of surface roughness and peak count for cold-rolled metal sheet (strip)
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 — Spark discharge atomic emission spectrometric method (routine method)
GB/T 8170 Rules of rounding off for numerical values & expression and judgement of limiting values
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 20125 Low-alloy steel — Determination of multi-element contents — Inductively coupled plasma atomic emission spectrometric method
3 Term and definition
For the purposes of this document, the following term and definition apply.
3.1
quenching and partitioning steels; QP
steel whose microstructure is martensite, retained austenite and ferrite, during the forming process, the retained austenite which may be transformed into martensite with high work hardening rate, uniform elongation and tensile strength, and compared with dual phase steel with the same tensile strength, which has higher elongation; compared with transformation induced plasticity steel with the same tensile strength, which has lower carbon equivalent
4 Classification and code
4.1 The designation of steel sheet and strip consists of three parts: the initials "CR" of “Cold Rolled”, the specified minimum yield strength value/specified minimum tensile strength value, and the initials “QP” of “Queuing” and “Partitioning”.
Example: CR550/980QP
CR——initials of “Cold Rolled”;
550/980——550: the specified minimum yield strength value, MPa; 980: the specified minimum tensile strength value, MPa;
QP——initials of “Quenching and Partitioning”.
4.2 Steel sheets and strips are classified according to the surface quality shall meet those specified in Table 1.
Table 1 Surface quality
Grade Code
Relatively high grade surface FB
High grade surface FC
4.3 Steel sheets and strips are classified by surface structure shall meet those specified in Table 2.
Table 2 Surface structure
Surface structure Code
Pitted surface D
Bright surface B
5 Order information
5.1 Contracts or orders made based on this part shall include the following items:
a) product name (steel sheet or strip);
b) number of this part;
c) designation;
d) dimension and accuracy;
e) surface quality grade;
f) surface structure;
g) edge state;
h) packaging method;
i) weight;
j) application;
k) other special requirements.
5.2 If information such as dimension and roughness precision, surface quality grade, surface structure type, edge condition and packaging, is not specified in the order contract, the supplier shall supply this part of products in common size and common roughness precision, relatively high grade surface and trimming steel sheet or strip with pitted surface structure, and shall pack the products in the methods given by the supplier.
6 Dimension, shape and weight
The dimension, shape, weight and tolerance of steel sheets and strips shall meet those specified in GB/T 708.
7 Technical requirements
7.1 Chemical composition
See Annex A for reference values of chemical composition (melting analysis) of steels. If the purchaser has any requirements for chemical composition, it shall be negotiated when ordering. The tolerances of the chemical composition of the finished steel sheet and strip shall meet the requirements of GB/T 222.
Foreword i
1 Scope
2 Normative references
3 Term and definition
4 Classification and code
5 Order information
6 Dimension, shape and weight
7 Technical requirements
8 Test methods
9 Inspection rules
10 Packaging, marking and quality certificate
Annex A (Informative) Reference values of chemical composition
