GB/T 38809-2020 English PDF (GB/T38809-2020)

Delivery: 3 seconds. Download true-PDF + Invoice.
Get Quotation: Click GB/T 38809-2020 (Self-service in 1-minute)
Historical versions (Master-website): GB/T 38809-2020
Preview True-PDF (Reload/Scroll-down if blank)

GB/T 38809-2020: General Specification for Low Alloy Ultra-high Strength Steels
GB/T 38809-2020
General specification for low alloy ultra-high strength steels
ICS 77.140.20
H40
National Standards of People's Republic of China
General technical conditions for low-alloy ultra-high-strength steel
2020-06-02 released
2020-12-01 implementation
State Administration for Market Regulation
Issued by the National Standardization Management Committee
Preface
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard was proposed by the China Iron and Steel Association.
This standard is under the jurisdiction of the National Steel Standardization Technical Committee (SAC/TC183).
Drafting organizations of this standard. Central Iron and Steel Research Institute, Fushun Special Steel Co., Ltd., Jiangyin Xingcheng Special Steel Co., Ltd., Air China
Industrial Group Corporation Shenyang Aircraft Design Institute, Jiangsu Yonggang Group Co., Ltd., Metallurgical Industry Information Standards Institute, Xi'an Aerospace Power
Machinery Co., Ltd., Xi’an Changfeng Mechanical and Electrical Research Institute, Northwest Industrial Group Co., Ltd., Commercial Aircraft Corporation of China Co., Ltd. Shanghai Aircraft Design
Engineering Research Institute, Fangda Special Steel Technology Co., Ltd.
The main drafters of this standard. Han Shun, Li Jianxin, Li Yong, Zhao Bo, Dai Qiang, Wu Jun, Pang Xuedong, Zheng Shuli, Du Wenhui, Wu Qiuping, Wu Xiaolin,
Liu Yuanjie, Chen Yuanqing, Meng Yu, Yan Chengming.
General technical conditions for low-alloy ultra-high-strength steel
1 Scope
This standard specifies the order content, size, shape, weight, technical requirements, test methods, inspection rules, and packages of low-alloy ultra-high-strength steel.
Installation, logo and quality certificate.
This standard applies to rolled or forged low-alloy ultra-high-strength steel bars (hereinafter referred to as steel bars).
The grades and chemical composition specified in this standard are also applicable to steel ingots, billets or their products.
2 Normative references
The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this article
Pieces. For undated references, the latest version (including all amendments) applies to this document.
GB/T 222 Allowable deviation of chemical composition of finished steel
GB/T 223.11 Determination of chromium content in steel and alloy by visual titration or potentiometric titration
GB/T 223.17 Methods for chemical analysis of iron, steel and alloy The diantipyrine methane photometric method for the determination of titanium content
GB/T 223.23 Iron, steel and alloy-Determination of nickel content-Dimethylglyoxime spectrophotometric method
GB/T 223.26 Steel and alloy determination of molybdenum content-Thiocyanate spectrophotometric method
GB/T 223.43 Determination of tungsten content in iron, steel and alloy by gravimetric method and spectrophotometric method
GB/T 223.53 Methods for chemical analysis of iron, steel and alloy-The flame atomic absorption spectrophotometric method for the determination of copper content
GB/T 223.58 Methods for chemical analysis of iron, steel and alloy. The sodium arsenite-sodium nitrite titration method for the determination of manganese content
GB/T 223.59 Steel and alloy determination of phosphorus content-Bismuth phosphomolybdenum blue spectrophotometric method and antimony phosphomolybdenum blue 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 223.69 Steel and alloy carbon content determination after combustion in tube furnace gas volume method
GB/T 223.72 Gravimetric method for determination of sulfur content in steel and alloy
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 224 steel decarburization depth measurement method
GB/T 226 Steel Macrostructure and Defect Inspection Method
GB/T 228.1 Tensile Test of Metallic Materials Part 1.Room Temperature Test Method
GB/T 229 Charpy pendulum impact test method for metallic materials
GB/T 231.1 Brinell Hardness Test of Metallic Materials Part 1.Test Method
GB/T 702 Hot-rolled steel bar size, shape, weight and allowable deviation
GB/T 908 Forged steel bar size, shape, weight and allowable deviation
GB/T 2101 General requirements for acceptance, packaging, marking and quality certificate of section steel
GB/T 2975 Steel and steel product mechanical performance test sampling location and sample preparation
GB/T 4161 Metallic materials plane strain fracture toughness KIC test method
GB/T 4162-2008 Ultrasonic testing method for forged and rolled steel bars
GB/T 4336 Carbon steel and medium and low alloy steel determination of multi-element content spark discharge atomic emission spectrometry (conventional method)
GB/T 6394 Method for determination of average grain size of metals
GB/T 8170 Numerical rounding rules and the expression and determination of limit values
GB/T 10121 Steel tower-shaped hairline magnetic particle inspection method
GB/T 10561-2005 Determination of the content of non-metallic inclusions in steel Standard Grading Chart Microscopic Inspection Method
GB/T 13298 Metal Microstructure Inspection Method
GB/T 13299 Steel Microstructure Evaluation Method
GB/T 15711 Testing Tower Shaped Hairline Acid Leaching Method for Non-metallic Inclusions in Steel
GB/T 17505 General technical requirements for delivery of steel and steel products
GB/T 20066 Sampling and sample preparation methods for the determination of the chemical composition of steel and iron
GB/T 20123 Determination of total carbon and sulfur content of iron and steel-Infrared absorption method after combustion in high frequency induction furnace (conventional method)
GB/T 36026-2018 High-strength corrosion-resistant alloy rods for oil and gas engineering
GB/T 37566 Ultrasonic testing method for round steel
YB/T 5293 Upsetting test method for metallic materials
3 Order content
The contract or order for ordering according to this standard shall include at least the following contents.
a) The standard number;
b) Product name;
c) grade;
d) Specifications and accuracy (see Chapter 4);
e) weight;
f) Smelting method (see 5.2);
g) Delivery status (see 5.3);
h) The items or indicators in the standard that should be negotiated between the supplier and the buyer and indicated in the contract (the supplier will choose if it is not indicated);
i) Special requirements (see 5.16).
4 Dimensions, appearance and weight
4.1 See Table 1 for the applicable maximum dimensions of steel bars.
Table 1 Maximum size of steel rod
4.2 The size, shape and allowable deviation of the rolled steel bar shall comply with the provisions of GB/T 702, and the specific requirements shall be indicated in the contract.
4.3 The size, shape and allowable deviation of forged steel bars shall comply with the provisions of GB/T 908, and the specific requirements shall be indicated in the contract.
4.4 Steel rods are delivered in actual weight.
5 Technical requirements
5.1 Brand and chemical composition
5.1.1 The steel grade and chemical composition (melting analysis) should meet the requirements of Table 2.
Table 2 Grades and chemical composition
5.1.2 The allowable deviation of the chemical composition of the finished steel bar shall meet the requirements of Table 3.The allowable deviation of the elements not listed in Table 3 shall comply with GB/T 222
Provisions.
Table 3 Allowable deviation of chemical composition of finished product
5.2 Smelting method
The smelting method of steel should meet the requirements of Table 4.
Table 4 Smelting method, delivery status and delivery hardness
Serial number, grade, smelting method, delivery status, delivery hardness/HBW
1 40CrNi2MoA electroslag remelting or vacuum arc remelting normalizing high temperature tempering, annealing ≤269
2 40CrNi2Si2MoVA vacuum induction plus vacuum arc remelting normalizing high temperature tempering, annealing ≤241
3 42CrNi2Si2MoVA vacuum arc remelting normalizing high temperature tempering, annealing ≤311
4 30CrMnSiNi2A vacuum induction plus vacuum arc remelting normalizing high temperature tempering, annealing ≤269
5 30Si2MnCrMoVE Vacuum induction plus vacuum arc remelting annealing ≤285
6 31Si2MnCrMoVE Vacuum induction plus vacuum arc remelting annealing ≤285
7 45CrNiMo1VA
Vacuum induction plus electroslag remelting or vacuum induction plus
Vacuum arc remelting
Annealing, high temperature tempering≤285
5.3 Delivery status
5.3.1 The delivery status of steel bars should meet the requirements of Table 4.
5.3.2 According to the requirements of the purchaser and specified in the contract, the steel bars can be delivered in the state of turning, peeling or polishing.
5.4 Delivery hardness
The delivery hardness of the steel bar should meet the requirements of Table 4.
5.5 Mechanical properties
5.5.1 Cut the sample blank from the steel bar, and the mechanical properties after heat treatment according to the recommended heat treatment system in Table 5 should meet the requirements of Table 5.
Among them. 40CrNi2Si2MoVA, 30CrMnSiNi2A steel bar when the transverse mechanical properties are qualified, the longitudinal mechanical properties may not be tested.
5.5.2 The plane strain fracture toughness KIC of 30Si2MnCrMoVE and 31Si2MnCrMoVE steel bars shall not be less than 80MPa·m1/2,
When the nominal size is greater than 300mm, take a sample on the forged 90mm square melt sample.
Table 5 Mechanical properties
5.6 Low power
5.6.1 Steel rods shall be subjected to acid leaching low power inspection, and there shall be no shrinkage holes, voids, pinholes, peeling, cracks, white spots, delamination, and
Defects such as dissimilar metal inclusions and non-metallic inclusions.
5.6.2 The qualified level of acid leaching low-magnification defects of steel bars shall meet the requirements of Table 6.
Table 6 Qualified level of low magnification defects
5.8 Upsetting
5.8.1 The 30CrMnSiNi2A steel bar with a nominal size not greater than 80mm shall be subjected to an upsetting test. The height of the sample after hot upsetting is the original sample
One-third of the height, the height of the sample after cold upsetting is one-half of the height of the original sample, there should be no cracks and cracks on the sample after upsetting. according to
According to the request of the buyer, after negotiation between the supplier and the buyer and indicated in the contract, the 30CrMnSiNi2A steel bar with a nominal size greater than 80mm can be upset forged
test.
5.8.2 According to the requirements of the purchaser and indicated in the contract, the other grades can be subjected to upsetting test.
5.9 Decarburization layer
5.9.1 There should be no decarburization layer on the surface of steel bars delivered in the state of turning, peeling or polishing.
5.9.2 Decarburization layer is allowed on the surface of the bar that is used for re-forging or whose nominal size is greater than 160mm. The qualified depth is determined by the negotiation between the supplier and the buyer.
Fixed, and specify in the contract.
5.10 Non-metallic inclusions
Steel rods should be inspected for non-metallic inclusions, and the inspection results should meet the requirements of Table 7.
Table 7 Qualified level of non-metallic inclusions
5.11 Grain size
The steel bar shall be inspected for austenite grain size after heat treatment in accordance with the provisions of Table 8, and its qualified level shall comply with the provisions of Table 8.
Table 8 Heat treatment and qualified level of grain size samples
5.12 Microstructure
There should be no flake pearlite in the microstructure of 30Si2MnCrMoVE and 31Si2MnCrMoVE steel bars.
5.13 Purity
40CrNi2Si2MoVA, 42CrNi2Si2MoVA steel rods should be subjected to magnetic particle testing, the maximum average frequency F should not be greater than 0.10, the maximum
The average severity S should not be greater than 0.20.
5.14 Ultrasonic testing
Steel rods should be subjected to ultrasonic testing, and the qualification level should meet the requirements of Table 9.
Table 9 Qualified Level of Ultrasonic Testing
5.15 Surface quality
5.15.1 There should be no visible cracks, scars, folds and inclusions on the surface of the steel rod for pressure processing. If any of the above defects should be removed,
The removal depth should meet the requirements of Table 10 from the actual size of the steel bar, and the removal width should not be less than 5 times the depth. Maximum at the same section
The depth of removal should not be more than one. Individual small scratches, indentations and pits that do not exceed one half of the tolerance from the actual size are allowed
exist.
Table 10 The allowable removal depth of surface defects of steel bars for pressure processing is in mm
Nominal size of steel bar, the same section allows clearance depth
≤80 1/2 of the nominal size tolerance
>80~140 Tolerance of nominal size
>140~2005% of nominal size
>200 6% of size, the deepest does not exceed 12mm
5.15.2 The surface of the steel bar used for cutting is allowed to have local defects that do not exceed those specified in Table 11 from the nominal size of the steel bar.
Table 11 The allowable depth of local defects on the surface of steel rods for cutting is mm
Nominal size of steel bar partial defect allowable depth
< 100 Negative deviation of nominal size
≥100 Tolerance of nominal size
5.16 Special requirements
According to the requirements of the buyer, after negotiation between the supplier and the buyer, and indicated in the contract, steel bars with the following special requirements can be supplied.
a) Special smelting methods;
b) Special chemical composition;
c) Special hardness value;
d) Special plane strain fracture toughness KⅠC;
e) Provide the measured values of the elongation after fracture, impact absorption energy and plane strain fracture toughness of 42CrNi2Si2MoVA steel bars;
f) Qualified level of special ultrasonic testing; ...