1 Scope
This document specifies the classification and grade of cold-rolled isotropic high-strength steel plates and strips, the content of orders, dimensions. Shape, weight. Technical requirements, test methods, inspection rules. Packaging, marking and quality certification, etc.
This document applies to the thickness of not more than 2.5 mm, mainly used for the production of automotive outer cover of cold-rolled isotropic high-strength steel plates and strips (hereinafter referred to as "steel plates and strips").
2 normative reference documents
The contents of the following documents constitute the essential provisions of this document through the normative references in the text. Among them, note the date of the reference document, only the date of the corresponding version applies to this document; do not note the date of the reference document, its latest version (including all the revision of the list) applies to this document.
GB/T 223,5 Determination of acid-soluble silicon and total silicon content of iron and steel reduced silicon molybdate spectrophotometric method
GB/T 223.9 steel and alloy aluminum content of the determination of chromium azure S spectrophotometric method
GB/T 223.40 steel and alloy saw content of the determination of chlorosulfuric acid S spectrophotometric method
GB/T 223,59 steel and alloy phosphorus content determination - bismuth phosphorus molybdenum blue spectrophotometric method and antimony phosphorus molybdenum blue spectrophotometric method
GB/T 223.63 steel and alloy chemical analysis method sodium periodate (potassium) photometric method for the determination of manganese
GB/T223.64 iron and steel and alloy manganese content determination flame atomic absorption spectrometry
GB/T 223.76 iron and steel and alloy chemical analysis method flame atomic absorption spectrometry determination of vanadium
GB/T 223.78 steel and alloy chemical analysis method curcumin direct photometric determination of boron content
GB/T 223.84 steel and alloys, the determination of titanium content of the two-antipyrine methane spectrophotometric method
GB/T 223.85 steel and alloy sulfur content of the determination of induction furnace combustion after infrared absorption method
3 terms and definitions
GB/T 5027 defined as well as the following terms and definitions apply to this document.
3.1
Isotropic steel isotropic steel
The plastic strain ratio (r value) is limited, with isotropic properties and good tensile forming properties of steel. Usually plate in-plane plasticity
strain ratio anisotropic degree is small.
4 Classification and grading methods
4.1 Grading method
The grade of steel plate and strip consists of the initials "CR" of "ColdRolled", the specified minimum yield strength value, the isotropic value, and the isotropic value.
The grade is composed of the first two letters of the English word "Isotropic", "IS".
Example: CR2201S, where:
CR a cold-rolled English "ColdRolled" initials;.
220 - specified minimum yield strength value in MPa (MPa);
IS-isotropic English "tropic" of the first two letters.
4.2 Classification
4.2.1 Steel plates and strips by grade and recommended uses are shown in Table 1.
5 Order content
5.1 The contract or order according to this document shall include the following contents:
a) Product name (steel plate or strip);
b) The document number;
c) Grade;
d) specifications and dimensions, unevenness accuracy:
e) Surface quality level;
f) Surface structure;
g) Edge condition;
h) Packing method;
i) Weight;
j) Application;
k) Other special requirements.
5.2 If size and unevenness accuracy, surface quality level, surface structure type, edge condition and packaging are not specified in the order contract, the products will be treated as normal size and unevenness accuracy and more accurate. If the information of size and unevenness accuracy, surface quality level, surface structure type, edge state and packaging are not specified in the order contract, the products in this document shall be supplied as ordinary size and unevenness accuracy, higher level surface, cut edge steel plate or steel strip with pockmarked surface structure, and packaged according to the packaging method provided by the supplier.
6 Size, shape, weight
The size, shape, weight and allowable deviation of steel plate and strip shall conform to the provisions of GB/T 708.
7 Technical requirements
7.1 Chemical composition
The chemical composition of the steel (melting analysis) reference value is shown in Appendix A. If the demander has requirements on chemical composition. Should be negotiated at the time of order.
7.2 Smelting method
The steel used for steel plates and strips is smelted in oxygen converter or electric furnace, unless otherwise specified, the smelting method is chosen by the supplier.
7.3 Delivery status
7.3.1 Steel plates and strips shall be delivered in annealed and flattened condition.
7.3.2Steel plates and strips are normally supplied oiled and the oiled film shall be removable with alkaline aqueous solution or usual solvents. In the usual packaging, transportation, loading and storage conditions.
Under the usual conditions of packaging, transportation, loading and storage, the supplier guarantees that the surface of steel plates and strips will not rust within 6 months from the date of completion of manufacture. If the demander requires the supply without oiling, it should be negotiated at the time of order.
7.4 Mechanical properties
The supplier guarantees that the mechanical properties of the steel plates and strips shall conform to the provisions of Table 4 within 6 months from the date of manufacture.
Note: Due to the effect of aging, the mechanical properties of steel plates and strips will deteriorate with the extension of storage time, such as the rise of yield strength and tensile strength, the decrease of elongation after break, and the deterioration of forming properties. Tensile strain marks appear, so we suggest you to use them as soon as possible.
7.5 Tensile strain marks
Under the condition of room temperature storage, for the steel plates and strips with surface quality FC and FD, the tensile strain marks shall not appear when they are used within 6 months after the date of manufacture.
7.6 Surface quality
7.6.1 The surface of steel plates and strips should not have scars, cracks, inclusions and other defects harmful to the use of steel plates and strips should not be visually visible delamination.
7.6.2 The characteristics of the surface quality level of steel plates and strips are shown in Table 5.
7.6.3 For steel strips, as there is no opportunity to remove the defective part. Therefore, delivery with defects is allowed, but the defective part should not exceed 6% of the total length of each roll.
8 Test methods
8.1 The chemical composition of steel test a.. GB/T 4336, GB/T 20123, GB/T 20125. GB/T 20126 or general chemical analysis methods, arbitration by GB/T 223.5, GB/T 223.9, GB/T 223. 40. GB/T 223. 59, GB/T 223. 63, GB/T 223.64 . 223.76, GB/T 223.78 . GB/T 223.84, GB/T 223.85 and GB/T 223.86 of the provisions.
8.2 steel plates and strips The inspection items and test methods should be in accordance with the provisions of Table 7.
8.3 r value is calculated at 15% plastic strain, when the maximum force plastic elongation is less than 15%, the plastic strain value at the end of the maximum force plastic elongation. n value is calculated in the range of 10% ~ 20% plastic strain, when the maximum force plastic elongation is less than 20%, the calculated plastic strain range of 10% to the end of the maximum force plastic elongation.
9 Inspection rules
9.1 The inspection and acceptance of steel plates and strips shall be carried out by the inspection department of the supplier.
9.2 Steel plates and strips should be accepted by lot. Each inspection batch should be composed of the same grade, the same specification, the same processing state of the steel plate or strip. Each batch of
Weight should not be greater than 30t, for the volume of more than 30t of steel strip, each volume as an inspection batch.
9.3 steel plate and strip sampling number and sampling method should be consistent with the provisions of Table 7.
9.4 steel plate and steel strip re-testing and determination rules should be consistent with the provisions of GB/T17505.
9.5 chemical composition and mechanical properties of the test results according to the revised value of the comparison method for revision, revision rules according to the provisions of GB/T8170.
10 packaging, marking and quality certification
Steel plate and strip packaging, marking and quality certification should comply with the provisions of GB/T 247. The type of quality certificate (inspection documents) should be in accordance with the provisions of GB/T 18253-2018. If the demander has special requirements for packaging, it can be negotiated when ordering.
11 Domestic and foreign grade approximation comparison
The approximate comparison between the grades in this document and the foreign standard grades is shown in Appendix B.
Foreword
Introduction
1 Scope
2 normative reference documents
3 terms and definitions
4 Classification and grading methods
5 Order content
6 Size, shape, weight
7 Technical requirements
8 Test methods
9 Inspection rules
10 packaging, marking and quality certification
11 Domestic and foreign grade approximation comparison
Appendix A
Appendix B
Appendix C
Bibliography
