Some standard content:
National Standard of the People's Republic of China
Technical conditions for carburizing bearing steel
Specification for carburizing steel of bearings UDC669.141
.3.018
GB320382
This standard applies to carburizing bearing steel bars, hot-rolled and forged round steels and cold-drawn round steels used for making bearing rings and rolling elements. 1 Dimensions and appearance
1.1 Diameter and its allowable deviation
1.1.1 The diameter and allowable deviation of hot-rolled round steel shall comply with the provisions of Table 1. Table 1
Allowable deviation
Allowable deviation
Allowable deviation
The ovality of hot-rolled round steel shall not exceed 70% of the dimensional tolerance. 1.1.2 The diameter and allowable deviation of forged round steel shall comply with the provisions of GB908-72 "Forged round steel and square steel varieties". 1.1.3 The diameter and allowable deviation of cold drawn round steel shall comply with the relevant provisions of the 11th level of accuracy in GB905-82 "Dimensions, shape and weight of cold drawn steel and their allowable deviation". 1.2 Delivery length
The delivery length of steel is usually 3~~5m. For steel used in multi-station presses, the length can be 3~6㎡). Steel with a delivery length of not less than 2m is allowed, but its weight shall not exceed 10% of the total weight of the batch. National Bureau of Standards 1982-09-23 Issued
1983-07-01 Implementation
1.3 Curvature
GB 3203--82
The curvature of hot rolled and forged non-annealed steel shall not exceed 5mm per meter, the curvature of the whole bar shall not exceed 10mm, and the curvature of annealed material shall not exceed mm per meter.
The curvature of cold-drawn round steel shall comply with the requirements of the 11th accuracy level in B 905-82. 1.4 Torsion
The steel shall not have significant torsion.
1.5 End shape
The end shall be sawn neatly and shall not have horseshoe shape, flash, burr, bevel or flattening that affects the use. Gas cutting of steel is not allowed. 2 Technical requirements
2.1 Grade and chemical composition:
Melt composition
Steel shall be delivered according to the melt composition. The grade and chemical composition (melting analysis) of steel shall comply with the requirements of Table 2. Table 2
G20CrMo
: G20CrNiMo
G 20CrNi2Mo
G20Cr2Ni4
G10CrNigMe
G20Cr2Mn2Mo
Core, 40
, device
and the letter "A" is marked after the grade
When it is supplied as high-grade quality steel, its sulfur and phosphorus content should not exceed 0.020%. 2.1.2 Permissible deviation of chemical composition of finished steel products The chemical composition of steel and steel products is allowed to have deviations specified in Table 3 compared with Table 2. Table 3
Chemical composition
Permissible deviation
2.2 Smelting method:
Steel should be smelted in electric furnace or furnace, or electric furnace or open-hearth furnace steel liquid should be refined outside the furnace. High-quality steel shall also be electroslag remelted. Other smelting methods that meet the requirements of this standard may also be used upon agreement between the supplier and the buyer. 2.3 Delivery status:
GB 3203-82
Hot-rolled or forged steels shall be delivered in the hot-rolled (forged) state or in the annealed state: drawn steels shall be delivered in the annealed (or tempered) state.
2.4 Mechanical properties;
2.4.1 The longitudinal mechanical properties of steels measured by the test specimens made from heat-treated rough pieces shall comply with the requirements of Table 4. Table
G20CrNtMn
G 20CrNi2Me
G20Cr2Ni4
G10CrVi3Mo
G2[Cr2Mn2Mo
Specimen rough
damage diameter
Temperature, ℃
RRO ±
Second time
790 ±
20 ℃
880 ±
20 ℃
790 ±
810 ±
Note: The accumulated data of mechanical properties of G 20CrMo are for reference only. Cold
Temperature, ℃
150～
Tensile strength
kgf mm?
Elongation
Shrinkage
Not less than
Impact value
The mechanical properties listed in Table 4 are applicable to steels with "small cross-section size" and 180mm. For steels with sizes of 81-100mm, the elongation, shrinkage and impact values are allowed to be reduced by 1 unit, 5 units and 5% respectively compared with the provisions of Table 4; for steels with sizes of 101-150rmn, the elongation, shrinkage and impact values are allowed to be reduced by 2 units, 10 units and 10% respectively compared with the provisions of Table 4: for steels with sizes of 151-250mm, the elongation, shrinkage and impact values are allowed to be reduced by 3 units, 5 units and 15% respectively compared with the provisions of Table 4. When the steel with size greater than 80 mm is rolled or forged into 70-80 mm II, the results shall comply with the provisions of Table 4. 2.4.2 For steel delivered in annealed state, the hardness is: G20Cr2Vi4 (A) not less than 241, and the hardness of other steel grades not less than 229. 2.5 Hardenability:
For G20CrNiMo and G20CrNi2Mα steels, the end hardenability requirements shall comply with the provisions of Table 5. Table 5
Breaking strength HRC
G 20C tNiMa
G 20CrNi2 Mo
Test bar Heat treatment system
920～950, 60min, normalizing
900±20℃, 1530nin, water
920±20 c, 30 min. Fire
920±20r, 15~30min, water
Distance from wood end, mm
40～48
41 ~ 48
Note: For steel grades not listed in the table, the end permeability test can also be carried out according to the request of the purchaser, and the hardness value is for reference. 9.0
2.6 Acid leaching macrostructure and tower shape:
GB 320382
2.6.1 Steel should be subjected to acid leaching macrostructure inspection. There should be no shrinkage, internal bubbles, cracks, peeling, slag, pits and overburning on the transverse acid leaching test piece of steel. The center looseness, general looseness and ingot-shaped segregation of macrostructure should be evaluated according to the first, ..., and first level diagrams of GB1979-80 "Structural Steel Macrostructure Defect Rating Diagram", and its qualified level should comply with the provisions of Table 6. Table 6
High-quality
Central looseness
Qualified level, unqualified
First-stage looseness
Ingot-shaped labeling
2.6.2 Steel with a diameter greater than 16mm should be subjected to acid leaching tower-shaped test specimen inspection. The dimensions of the tower specimen are: the first step is D-6mm, the second step is D×
-mm, the third step is D
, the length of each step is 50mm,
(D is the nominal diameter of the finished steel in mm)
High-quality steel is not allowed to have hairline cracks. The requirements for the grain of high-quality steel shall comply with the provisions of Table 7
G20CrMo
G20C:-ViMn
G2C -N i2Mc
G20C r2N14
GI0c:rNiaMo
G 20C. +2Mn2 Mo
The maximum grain of each order
The total length of each order
Total grain
Total grain
The starting length of grain is 0.6mm. When the distance between two grains on the same busbar is less than 2mm, it is calculated as one, and the existence of connecting two grains is not allowed.
2.7 Non-metallic inclusions:
Non-metallic inclusions in steel shall be evaluated according to the fourth level diagram of YB9-68 "Technical Conditions for Chromium Bearing Steel", and their qualified level shall comply with the provisions of Table 8.
High-quality steel
2.8 Grain size:
Brittle sharp inclusions
Plastic fire inclusions
Point-shaped non-deformed cool inclusions
The austenite grain size of steel is 5 to 8 (carburizing method, other methods can also be used, but carburizing method is used for arbitration). 2.9 Microstructure:
GB 320382
For G20CrNiMo and G20CrNi2Ma steel, the banded structure should not exceed grade 1-3. The banded structure is checked in the annealed state. For steel materials that are not annealed, the banded structure of the annealed state can also be checked in the hot-rolled state. 2.10 Surface quality:
Steel materials should be well treated, and the surface should not have cracks, folds, cracks, scars, light impurities and other defects that are harmful to the state. The surface of cold-drawn steel should be clean and free of rust.
The depth of removal of harmful defects on the surface of steel for pressure processing, calculated from the actual size, shall not exceed half of the inch tolerance for round steel with a diameter less than or equal to 80mm, and shall not exceed the size tolerance for round steel with a diameter greater than 80mm. The depth of removing harmful defects on the long surface of steel for cutting processing shall not exceed half of the tolerance of the dimension for round steel with a diameter less than or equal to 80mm, and shall not exceed half of the tolerance for round steel with a diameter greater than 80mm, from the nominal size. For round steel for cutting processing, surface defects whose depth does not exceed half of the tolerance do not need to be removed. 2.11 Ultrasonic inspection: For G20CrNi2MoA and G20Cr2Ni4A steels, the supplier must conduct ultrasonic flaw detection on each steel or steel material. For other steel grades and the above two high-quality steel grades, this inspection shall be carried out upon the request of the buyer. The ultrasonic inspection method shall be carried out in accordance with the current technical standards of each supplier. 2.12 The above inspection items may be reduced upon the request of the buyer. 3 Test methods
Steel quality test methods and sampling requirements shall comply with the requirements of Table 9. For finished steel with a diameter greater than 13 μm, all mechanical properties and high and low magnification test items (inclusions, low magnification, mechanical properties, banding, grain size, end permeability, tower shape) can be forged into 70-8 mm round steel for retrograde testing. Table 9
Non-metallic
Crystallinity
Sampling location
Electric furnace and open hearth furnace are for melting Refining and burning area, electroslag ingot head>60mm steel, electric donkey, open hearth steel as the head, electric cleaning steel head and tail, 60mm electric guard, any part of open furnace steel, electric flat steel head, self-slag steel Yimin part, different root steel, large root steel, different root steel 20C: r2 Mu2M.
G20CrMo
Number of samples, pcs
G20 rNiMo
G20C-Ni2Mo
G 20C r2N14
G10crNi3Mo
Test method
GH 222-63
GH 223—81.82
YH 35-78
YB 9-68
GB226-77
GB 1979—80 Rating chart
GB228-—76
GB229--63
GB2975—82
GB 231—63
YB 31—64
YB 27—77
Wood end area
Ultrasonic
Table business version
The most inspection
Shape
Texture inspection
4 Inspection rules
Government sample department letter
Different root steel
Branch or material
Branch or material
Branch or material
Electric furnace, open hearth steel, electric slag steel fire tail
4.1 Inspection and acceptance
GB3203—82
Continued table 9
Sampling number
G 200. r2Mn2 Mn :
G2nCrMo
Quantity, not
G20CrNiMo
G20CrNi2Mo
G20t:r2i4
GioCrNisMo
Test method
GB 225—63
Each production! Current method
Limited or other effective methods
YB 47—R4
The inspection and acceptance of steel products shall be carried out by the supplier's technical supervision department. The purchaser has the right to inspect and accept according to the provisions of this standard. 4.2 Batch rules
Steel products shall be inspected and accepted in batches. Each batch shall consist of steel products with the same smelting furnace number, the same processing method, the same size, the same delivery status and the same heat treatment furnace. The electroslag furnace is batched according to the electroslag furnace number. When the electroslag process is stable and can ensure compliance with the technical requirements of this standard, it is allowed to batch according to the consumable electrode mother furnace number. However, the supplier shall provide chemical composition data according to the electroslag furnace number and indicate the electroslag furnace number on the steel.
4.3 Re-test and judgment rules
When a certain test result is unqualified (except white spots), it is allowed to take double the number of samples for re-testing the unqualified item. If the re-test result is still unqualified, the supplier may re-heat treat or re-batch as a new batch for acceptance. S Packaging, marking and quality certificate
The packaging, marking and quality certificate of hot-rolled, forged and cold-drawn steel shall comply with the relevant provisions of GB2101-80 "General Provisions for Acceptance, Packaging, Marking and Quality Certificate of Section Steel". Additional remarks:
This standard was proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard was drafted by Daye Steel.
The main drafters of this standard are Rui Qiang and Zhang Fengbi. * If one batch is made of electroslag furnace, only one sample is inspected from each furnace. If the current steel is grouped by base material furnace number, two samples are taken from each batch.82
YH 35-78
YB 9-68
GB226-77
GB 1979—80 rating chart
GB228-—76||tt ||GB229--63
GB2975—82
GB 231—63
YB 31—64
YB 27—77
Wood end area
Ultrasonicbzxz.net
Table business version
The most inspection
Shape hair
Texture inspection|| tt||4 Inspection rules
Government sample letter
Different steel
Branch by bran or material
Branch by bran or material
Branch by ring Or material
Electric furnace, open hearth steel at will, electroslag steel fire tail
4.1 Inspection and acceptance
GB3203—82
Continued Table 9| |tt||Number of samples
G 200. r2Mn2 Mn :
G2nCrMo
Quantity, no
G 20CrNiMo
G20C rNi2Mo
G20t:r2i4
G ioCrNisMo
Test method
GB 225—63
Each production! Current method| |tt||Meat limit or other effective methods
YB 47—R4
The inspection and acceptance of steel products shall be carried out by the supplier's technical supervision department. The purchaser has the right to conduct inspection and acceptance in accordance with the provisions of this standard. 4.2 Batch rules
Steels should be inspected and accepted in batches. Each batch should consist of steels with the same smelting furnace number, same processing method, same size, same delivery state and same heat treatment furnace. The electroslag furnaces are batched according to the electroslag furnace number. When the electroslag process is stable and can be guaranteed to meet the technical requirements of this standard, it is allowed to be batched according to the consumable electrode mother furnace number. However, the supplier shall provide chemical composition data according to the electric slag furnace number and indicate the electric slag furnace number on the steel.
4.3 Re-test and judgment rules
When a certain test result fails (Except for white spots), it is allowed to take double the number of samples to retest the unqualified items. If the retest results are still unqualified, the supplier can re-heat treat or re-batch as a new batch for acceptance. Packaging, marking and quality certificate
The packaging, marking and quality certificate of hot-rolled, forged and cold-drawn steel shall comply with GB2101-80 "General Provisions for Acceptance, Packaging, Marking and Quality Certificate of Steel" Related regulations. Additional notes:
This standard was proposed by the Ministry of Finance Industry of the People's Republic of China. This standard was drafted by Daye Steel.
Who are the main drafters of this standard? Rui Qiang, Zhang Fengbi . * If one batch is an electroslag furnace, only one piece is inspected from each furnace. If the electric current steel is grouped into batches according to the base material furnace number, two pieces are taken from each batch.82
YH 35-78
YB 9-68
GB226-77
GB 1979—80 rating chart
GB228-—76||tt ||GB229--63
GB2975—82
GB 231—63
YB 31—64
YB 27—77
Wood end area
Ultrasonic
Table business version
The most inspection
Shape hair
Texture inspection|| tt||4 Inspection rules
Government sample letter
Different steel
Branch by bran or material
Branch by bran or material
Branch by ring Or material
Electric furnace, open hearth steel at will, electroslag steel fire tail
4.1 Inspection and acceptance
GB3203—82
Continued Table 9| |tt||Number of samples
G 200. r2Mn2 Mn :
G2nCrMo
Quantity, no
G 20CrNiMo
G20C rNi2Mo
G20t:r2i4
G ioCrNisMo
Test method
GB 225—63
Each production! Current method| |tt||Meat limit or other effective methods
YB 47—R4
The inspection and acceptance of steel products shall be carried out by the supplier's technical supervision department. The purchaser has the right to conduct inspection and acceptance in accordance with the provisions of this standard. 4.2 Batch rules
Steels should be inspected and accepted in batches. Each batch should consist of steels with the same smelting furnace number, same processing method, same size, same delivery status and same heat treatment furnace. The electroslag furnaces are batched according to the electroslag furnace number. When the electroslag process is stable and can be guaranteed to meet the technical requirements of this standard, it is allowed to be batched according to the consumable electrode mother furnace number. However, the supplier shall provide chemical composition data according to the electric slag furnace number and indicate the electric slag furnace number on the steel.
4.3 Re-test and judgment rules
When a certain test result fails (Except for white spots), it is allowed to take double the number of samples to retest the unqualified items. If the retest results are still unqualified, the supplier can re-heat treat or re-batch as a new batch for acceptance. Packaging, marking and quality certificate
The packaging, marking and quality certificate of hot-rolled, forged and cold-drawn steel shall comply with GB2101-80 "General Provisions for Acceptance, Packaging, Marking and Quality Certificate of Steel" Related regulations. Additional notes:
This standard was proposed by the Ministry of Finance Industry of the People's Republic of China. This standard was drafted by Daye Steel.
Who are the main drafters of this standard? Rui Qiang, Zhang Fengbi . * If one batch is an electroslag furnace, only one piece is inspected from each furnace. If the electric current steel is grouped into batches according to the base material furnace number, two pieces are taken from each batch.
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