GB/T 24238-2017 English PDF (GBT24238-2017)

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GB/T 24238-2017: Hot-Rolled Wire Rod for Prestressed Steel Wire and Strand
GB/T 24238-2017
Hot-rolled wire rod for prestressed steel wire and strand
ICS 77.140.60
H44
National Standards of People's Republic of China
Replacing GB/T 24238-2009
Preheated steel wire and strand for hot - rolled wire rod
2017-05-31 released
2017-12-01 implementation
General Administration of Quality Supervision, Inspection and Quarantine of the People 's Republic of China
China National Standardization Management Committee released
Preface
This standard is drafted in accordance with the rules given in GB/T 1.1-2009.
This standard instead of GB/T 24238-2009 "prestressed steel wire and strand with hot-rolled wire rod", compared with GB/T 24238-2009,
In addition to editorial changes, the main technical changes are as follows.
--- expand the scope of wire rod specifications;
--- cancel YL72A, YL77A, YL82A, YL87A four grades;
--- refine the brand sorbite content;
--- clear mesh cementite, the central martensite allow level requirements;
--- modify mechanical properties;
- Requirements for steep decarburization depth.
This standard is proposed by China Iron and Steel Industry Association.
This standard is under the jurisdiction of the National Steel Standardization Technical Committee (SAC/TC183).
The drafting unit of this standard. Anshan Iron and Steel Co., Ltd., Jiangsu Shagang Group Co., Ltd., Jiangsu Yonggang Group Co., Ltd., Tianjin Iron and Steel Group
Co., Ltd., Zhongtian Iron and Steel Group Co., Ltd., Qingdao Special Steel Co., Ltd., Tianyou Yinlong Prestressed Materials Co., Ltd., Baosteel
Group Nantong Wire Products Co., Ltd., Metallurgical Industry Information Standards Institute.
The main drafters of this standard. Zhai Liping, Yin Yi, An painted bamboo, Ren Maoyong, Ren Cuiying, Wang Lingjun, Nie Wenjin, Sui Zhisong, Sun Guangtao, Liu Cheng,
Wang Zhengmao, Xie Tieqiao, Chen Liang, Yu Jingqi, Hu Haiping, Liu Xuesen, Li Xiaobo, Shen Aiguo, Meng Zhaoxian, Gui Zhonglin.
This standard replaced the previous version of the standard release.
--- GB/T 24238-2009.
Preheated steel wire and strand for hot - rolled wire rod
1 Scope
This standard specifies the grade, order, size, shape, weight and allowable deviation of prestressed steel wire and strand wire.
Certification, test methods, inspection rules, packaging, marking and quality certificates.
This standard applies to pre-stressed steel wire and strand with hot-rolled wire rod (hereinafter referred to as wire rod).
2 normative reference documents
The following documents are indispensable for the application of this document. For dated references, only the dated edition applies to this article
Pieces. For undated references, the latest edition (including all modifications) applies to this document.
GB/T 222 Determination of chemical composition of finished steel
GB/T 223.5 Determination of silicon and total silicon content of iron and silicon in steel - Reduced molybdosilicate spectrophotometric method
GB/T 223.12 Methods for chemical analysis of iron, steel and alloy - Sodium carbonate separation - Diphenylcarbazide spectrophotometric method for the determination of chromium content
GB/T 223.14 Methods for chemical analysis of iron, steel and alloy - The tantalum reagent extraction spectrophotometric method for the determination of vanadium content
GB/T 223.19 Methods for chemical analysis of iron, steel and alloy The new sub-copper spirit-chloroform extraction spectrophotometric method for the determination of copper content
Iron and steel - Determination of nickel content - Dibutyl copper oxime spectrophotometric method GB/T
GB/T 223.59 Determination of phosphorus content of iron, steel and alloy - Bismuth phosphorus molybdenum blue spectrophotometric method and antimony phosphomolybdenum blue spectrophotometric method
GB/T 223.62 Methods for chemical analysis of iron, steel and alloy The butyl acetate extraction spectrophotometric method for the determination of phosphorus
GB/T 223.63 Methods for chemical analysis of iron, steel and alloy The sodium periodate (potassium) spectrophotometric method for the determination of manganese content
Iron and steel - Determination of sulfur content - Dimethyl blue spectrophotometric method GB/T
Iron and steel - Determination of carbon content - Burning furnace gas volume method in tubular furnace GB/T
Steel and alloys - Determination of sulfur content - Gravimetric method GB/T
GB/T 224 Determination of decarburization depth of steel
Metallic materials - Tensile testing - Part 1. Test methods for room temperature GB/T
General rules for GB/T 2101 steel acceptance, packing, marking and quality certificates
GB/T 2975 steel and steel products mechanical properties test sampling location and sample preparation
GB/T 4336 Determination of multi-element content of carbon and medium-low alloy steels - Spark discharge atomic emission spectrometry (conventional method)
GB/T 6394 Determination of average grain size of metals
Representation and Judgment of Numeric Ratification Rule and Limit Value of GB/T 8170
GB/T 10561 Determination of content of nonmetallic inclusions in steel Standard grading diagram Microscopy method
Test method for metallic microstructures GB/T
Hot - rolled disc strips - Dimensions, shape, weight and allowable deviation GB/T 14981-2009
Sampling and sample preparation methods for the determination of chemical constituents of steels and iron GB/T
GB/T .20123 Determination of total carbon and sulfur content of steel - High frequency induction furnace after combustion infrared absorption method (conventional method)
Metallographic Determination of Sorbite Content in YB/T 169 High Carbon Steel Wire Rod
Evaluation Method of Center Martensite for YB/T 4411 High Carbon Steel Wire Rod
Evaluation method of mesh cementite for YB/T 4412 high carbon steel wire rod
3 grades
The grades of steel are made up of alphabetical letters (capital), mean carbon content and manganese content symbol representing "stress". For example. YL82B.
among them.
YL --- "stress" of the Chinese phonetic prefix;
82 - the average carbon content specified by the standard (in ten thousandths);
B --- manganese content symbol.
4 order content
When ordering in accordance with this standard, the contract should include the following.
a) the standard number;
b) product name;
c) grade;
d) specifications;
e) size, shape accuracy level;
f) weight;
g) packaging and marking requirements;
h) special requirements (grain size, non-metallic inclusions, etc.).
5 size, shape, weight and allowable deviation
5.1 The size, shape and tolerances of the wire rod shall comply with the requirements of Class B and above Accuracy in GB/T 14981-2009. If the contract is not
Clear, according to GB/T 14981-2009 in the implementation of B-class accuracy.
5.2 The weight of the wire rod shall comply with the provisions of GB/T 14981-2009.
6 technical requirements
6.1 grades and chemical composition
6.1.1 The grade and chemical composition of smelting steel (smelting analysis) shall comply with the provisions of Table 1.
Table 1
Grade
Chemical composition (mass fraction) a, b /%
Cc Sid Mn PS Cre Nie Cue V
YL72B 0.70 to 0.75 0.10 to 0.30 0.60 to 0.90 ≤ 0.025 ≤ 0.025 ≤ 0.10 ≤ 0.10 ≤ 0.20 -
YL77B 0.75 to 0.80 0.10 to 0.30 0.60 to 0.90 ≤ 0.025 ≤ 0.025 ≤ 0.35 ≤ 0.10 ≤ 0.20 -
YL82B 0.80 to 0.85 0.10 to 0.30 0.60 to 0.90 ≤ 0.025 ≤ 0.025 ≤ 0.35 ≤ 0.10 ≤ 0.20 ≤ 0.15
YL87B 0.85 to 0.90 0.10 to 0.30 0.60 to 0.90 ≤ 0.025 ≤ 0.025 ≤ 0.35 ≤ 0.10 ≤ 0.20 f
a The supplier shall not intentionally add to the steel the alloying elements other than those specified in this table without the consent of the purchaser.
b If you want to change the prescribed chemical element content or increase or decrease the chemical element, it may be determined by consultation between the supply and demand sides.
c by the supply and demand sides, the lower carbon content can be reduced by 0.01%, or carbon content increased by 0.01%.
d When used for galvanizing, the silicon content can be determined by both parties.
(3) Negotiated by both supply and demand, not steel that is intentionally added with Cr, the (Cu Ni Cr) should be no more than 0.30%.
The f V content is determined by the supplier as required.
6.1.2 The permissible deviation of the chemical composition of the finished product shall comply with the provisions of GB/T 222.
6.1.3 Negotiated by both parties to the supply and demand and indicated in the contract that other grades and chemical composition may be supplied.
6.2 smelting method
Steel is smelted by converter or electric furnace and should be refined outside the furnace.
6.3 Delivery status
The wire rod is delivered in hot-rolled condition, each consisting of a wire rod.
6.4 Mechanical properties
Negotiated by the supply and demand sides, and in the contract that the wire rod tensile strength Rm and section shrinkage Z can be implemented in accordance with the provisions of Table 2.
Table 2
Grade
Stretching test
Tensile strength Rm/MPa Section shrinkage Z /% Tensile strength Rm/MPa Section shrinkage Z /%
Diameter 5.5mm ~ 10.0mm diameter 10.5mm ~ 16.0mm
YL72B 990 ~ 1110
YL77B 1120 ~ 1250
YL82B 1150 ~ 1300
YL87B protocol
≥30
970 ~ 1090
1100 ~ 1230
1130 ~ 1290
protocol
≥25
The performance value in the table is the value after the natural aging of the wire rod. Diameter 5.5mm ~ 10.0mm small size wire rod aging period of 15d, diameter 10.5mm ~ 16.0mm
Large-scale wire rod aging period 20d.
a diameter of less than 5.5mm or more than 16.0mm diameter of the wire rod mechanical properties negotiated by the supply and demand sides.
6.5 intrinsic quality
6.5.1 Decarburization layer
The depth of the total decarburization layer (ferrite transition layer) should not be greater than 1.0%
The nominal diameter of the bar).
6.5.2 Microstructure
6.5.2.1 The microstructure of the wire rod shall be mainly sorbite, and the sorbite content shall meet the requirements of Table 3.
table 3
Grade sorbite content minimum /%
YL72B 80
YL77B, YL82B, YL87B 85
6.5.2.2 Wire mesh shall be subjected to mesh cementite and center martensite test. Diameter 5.5mm ~ 10.0mm wire mesh mesh cement body should not be large
At the level 1, the center martensite should not be greater than 1.5; diameter 10.5mm ~ 16.0mm wire mesh mesh cement body should not be greater than 2, the center horse
The body should not be greater than 2.
6.5.3 SPECIAL REQUIREMENTS
The two sides agreed by the supply and demand, and specify in the contract, can be grain size, non-metallic inclusions and other tests, the specific level of permission in the order
Consultation.
6.6 Surface quality
6.6.1 The wire rod shall be partially cut away from the harmful parts of the head and tail, and the cross section shall not have shrinkage, delamination and inclusion.
6.6.2 wire rod surface should be smooth, there should be no cracks, folding, inclusions, ears, scarring, stratification and other harmful defects on the use.
6.6.3 The surface of the wire rod allows for slight local defects such as pits, pits and scratches with depth (or height) of not more than 0.10 mm.
7 test method
The number of sampling items, the sampling quantity, the sampling method and the test method of each batch shall be in accordance with the provisions of Table 4.
Table 4
Number test item sampling quantity sampling method test method
Chemical analysis 1/furnace GB/T .20066
GB/T 223 (applicable part),
GB/T 4336, GB/T .20123
2 Tensile test 2/batch GB/T 2975, different root GB/T 228.1
3 decarburization layer 2/batch different root bar GB/T 224
4 sorbite 2/batch different root wire rod YB/T 169
5 martensite 2/batch GB/T 13298, different root wire rod YB/T 4411
6 mesh cementite 2/batch GB/T 13298, different root wire rod YB/T 4412
7 non - metallic inclusions 2/batch different root bar GB/T 10561
8 grain size 2/batch different root GB/T 6394
9 size, shape by disk - micrometer, vernier caliper
10 surface by disk - visual
8 inspection rules
8.1 Inspection and acceptance
The inspection and acceptance of wire rods shall be carried out by the technical supervision department of the supplier.
8.2 Group Batch Rules
Tray should be approved in batches. Each batch by the same grade, the same furnace number, the same size of the wire rod composition.
8.3 Sampling quantity
The number of samples to be inspected shall be in accordance with Table 4.
8.4 re-examination and judgment
The reinspection and judgment of the wire rod shall conform to the provisions of GB/T 2101.
9 numerical correction
The numerical results of the inspection results of the wire rod should conform to the provisions of GB/T 8170.
10 Packaging, logo and quality certificate
10.1 The packing of the wire rod is marked by the contract. When the demand side is not clear, determined by the supplier.
10.2 The quality certificate of wire rod should conform to GB/T 2101.