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GB/T 12778-1991 Charpy impact fracture test method for metals

Basic Information

Standard ID: GB/T 12778-1991

Standard Name: Charpy impact fracture test method for metals

Chinese Name: 金属夏比冲击断口测定方法

Standard category:National Standard (GB)

state:Abolished

Date of Release1991-05-11

Date of Implementation:1992-01-01

Date of Expiration:2008-07-01

standard classification number

Standard ICS number:Metallurgy>>Metal material testing>>77.040.10Metal material mechanical testing

Standard Classification Number:Ships>>Ship General>>U05 Ship Materials and Inspection Methods

associated standards

alternative situation:Replaced by GB/T 12778-2008

Procurement status:≈ASTM E23-88,BS 131 Pt.5

Publication information

publishing house:China Standards Press

other information

Release date:1991-05-11

Review date:2004-10-14

Drafting unit:Luoyang Ship Material Research Institute

Focal point unit:National Technical Committee on Steel Standardization

Publishing department:State Bureau of Technical Supervision

competent authority:China Iron and Steel Association

Introduction to standards:

This standard specifies the determination method of the crystal area and lateral expansion value of the fracture of Charpy impact specimens of metal materials. This standard is applicable to the determination of the fracture of Charpy specimens (10mm×10mm×55mm, notch depth 2mm) of metal materials, and can also be used as a reference for the fracture of other types of impact specimens. GB/T 12778-1991 Determination method of metal Charpy impact fracture GB/T12778-1991 Standard download decompression password: www.bzxz.net

Some standard content:

192 Part 1 Testing methods for main building materials Standard ETT, indicating (for example, the temperature corresponding to 50% of the upper and lower platforms of impact absorption energy is recorded as ETIT) 3. Forward section rate - the temperature corresponding to the specified brittle section rate () in the temperature curve, expressed as FATT (for example, the temperature corresponding to 50% of the membrane section rate is recorded as FATT) C, Lateral expansion value - the temperature corresponding to a certain lateral expansion value between the upper and lower platforms of the temperature curve, expressed as LETT
B5 Brittle section rate and lateral expansion value are determined in accordance with GB/T12778. B6 The ductile-brittle transition temperatures determined by different force methods cannot be compared Additional remarks:
This standard is proposed by the Ministry of Metallurgical Industry of the People's Republic of China. This standard is owned by the Information Standards Research Institute of the Ministry of Metallurgical Industry. This standard is drafted by the Iron and Steel Research Institute of the Ministry of Metallurgical Industry. The main drafters of this standard are Li Jiulin and Liang Xinbang. 19. "Method for Determining Charpy Impact Fracture of Metals" GB112778-911 Subject content and scope of application
This standard specifies the method for determining the crystalline area and lateral expansion value of the fracture of composite impact specimens of metal materials. This standard is applicable to the determination of the fracture of Charpy specimens (1Umtm×10mm×55mm, notch depth 2mm) of metal materials. It can also be used as a reference for other types of impact specimen fractures. 2 Reference standards
GB229 Metal Charpy (U-notch) impact test method GB2106 Metal Charpy (V-notch) impact test method GB4159 Metal low overflow Charpy impact test method GB8170) Numerical rounding rules
3 Terminology
3.1 Impact specimen fracture Iraciure surface af irrpact specimen The fracture surface of the impact specimen after it is broken. Its macroscopic appearance is generally crystalline, fibrous (including shear lip) or mixed. 3.2 Crystalline fracture surface The fracture surface generally presents crystalline particles with metallic luster, and a flush fracture with obvious plastic deformation. 3.3 Crystallinity percentage The percentage of the total area of ​​the crystalline area in the fracture to the original cross-sectional area below the notch. 3.4 Fibrous fracture fibrous fructure surface The fracture surface generally presents a fiber morphology without metallic luster, and a fracture with obvious plastic deformation. 3.5 Fiber section ratio Perrenagcof fibrcusity The ratio of the total area of ​​the fiber area in the fracture to the original cross-sectional area below the notch. 3.6 Lateral expansion value lateralexpansinn
II. Construction steel
The sum of the largest increase in width on each side of the notch back of the fracture specimen, in mm4 Specimen
4.1 Test according to the provisions of GR229, GF2106 or GB4159, and the specimen after the impact is the test specimen of this standard.
The fracture surface of the specimen for measuring the crystalline area shall not be contaminated, rusted or bruised. 4.2
4.3 The specimen for measuring the lateral expansion value shall be prepared as follows: 2. Mark the same side on the side perpendicular to the notch; check whether there are burrs on the two sides perpendicular to the notch, and the burrs must be removed; check the expansion part, and there shall be no bruises. 5 Determination of crystalline area
Grass, 1 Comparison method
Compare the fracture surface of the impact specimen with the fiber section rate spectrum (Figure 1) or fiber section rate diagram (Figure 2) of the impact specimen fracture to estimate the fiber section rate.
Figure】Fiber cross-sectional area ratio of impact specimen fracture surface 194
Part I Testing methods and standards for major building materials 10%
5.2 Vernier caliper measurement method
Figure 2 Fiber cross-sectional area ratio of impact specimen fracture surface, from Figure 80%
According to the shape of the crystalline area on the fracture surface, if it can be classified into a rectangle or trapezoid (Figure 3), the corresponding size can be measured with a vernier caliper and directly checked in Table I.
Fiber non-
3 Schematic diagram of vernier caliper measurement method
4 A trapezoid, measure the mean of ab; a trapezoid, measure av42 and 2ar+a2)
Fiber cross-sectional area
Steel for construction
1.01.5]2.0 2.51 3.0|3.5/4.04.5 [5.07 5.516 ] 6.5|7.017.58.0] 8.5 [9.09.5 10Fiber cross-sectional area (%)
5.3 Magnified measurement method
Take a magnified photo of the sample fracture and use the integrator to measure the crystal area. 5.3.1
5.3.2 Use a low-power microscope or other optical instrument to measure the crystal area. 5.4 Card measurement method
Use a 10mm×10mm square hole card (Figure 4a) or a mesh card (Figure 4h) made of transparent plastic film to measure the crystalline area.
5.5 Calculation of cross-sectional area
Figure 4 Card for measuring the base crystalline area
() Hole card: () Mesh
According to the measured total area of ​​the crystalline area, calculate the crystalline cross-sectional area or fiber cross-sectional area of ​​the impact specimen fracture according to formula (1) or formula (2).
As×100%
Ag-Ar×100%
Where A,——Total area of ​​the tripod-shaped area in the fracture (mm\); ——Original cross-sectional area (mm2);
Part I Test Method Standard for Main Building Materials CA·---Crystal Cross-sectional Area;
FA——Fiber Cross-sectional Area.
6 Measurement of lateral expansion value
6.1 Expansion meter measurement method
6.1.1 Correct the zero position of the lateral expansion meter (see Figure 5), 6.1.2 First take a section of the sample, place the measured surface close to the reference seat, and the highest point of the expansion part is on the anvil surface of the dial indicator, and record the reading; then, take another section of the sample and repeat the above steps on the same side. The larger of the two measured values ​​is the expansion value of the sample on that side.
6.1.3 Repeat the above steps to measure the expansion value of the other side of the sample: 6.1.4 Add the expansion values ​​on both sides to obtain the lateral expansion value of the sample. ,2 Projector measurement method
6.2.1 Take a section of the sample, place it with the notch facing downward on the moving platform of the optical projector. Align one edge of the original width of the specimen with the reference line on the screen of the energy meter, record the reading on the transverse micrometer, then rotate the transverse micrometer to align the reference line with the highest point of the lateral expansion of the specimen, adjust the focal length, record the reading b, calculate the difference between the two values ​​(6, b), take another section of the specimen, and repeat the above steps on the same side. The larger of the two differences is the expansion of the specimen on that side. 6.2.2 Repeat the above steps to measure the expansion of the other side of the specimen. 6.2.3 Add the expansion of the two sections together to obtain the lateral expansion value of the specimen. 6.3 Vernier caliper measurement method
6.3.1 Measure the original width of the specimen Wm
6.3.2 Overlap the backs of the notches of the two cut specimens and make the side faces on the same plane (Figure 6). Xiaohai
Figure 5 Schematic diagram of lateral expansion against zero
Figure 6 Schematic diagram of lateral expansion value measurement
6.3.3 Compress the two specimens, make the measuring plate of the vernier caliper parallel to the side of the specimen, and measure the distance W between the highest points of lateral expansion of the fracture
6,3.4 If the two broken specimens are connected together, W can be directly measured with a vernier caliper. 6.3.5 The difference between the two measured values ​​(W,-W) is the lateral expansion value of the specimen. 7 Rounding off of the measurement results
The results are rounded off according to GB8170:
: The fiber (or product) cross-sectional area is rounded off to 1%: 5, and the lateral expansion value is retained to two significant figures. 8 Test report
The test report shall include the following contents:
: Product name, material, furnace batch number and sample number; 6. Sample type and size;
, test filterability;
α. Fiber (or crystalline) cross-sectional area ratio;
e. Lateral expansion value.
Additional remarks:
This standard is proposed by China State Shipbuilding Corporation. 2. Steel for construction
This standard was drafted by Luoyang Ship Material Research Institute, Jiangnan Shipyard and Dalian Shipyard of China State Shipbuilding Corporation, and Hudong Shipyard, Wuchang Shipyard, Jinzhou Heavy Machinery Plant and Shanghai Second Steel Plant participated in the drafting. The main drafters of this standard are Bi Chuantang, Xi Fangfei and Hua He. (II) Standard names, codes and main technical properties of common steel products for construction (steel part, steel section part) 1. Standard names and codes of steel products for construction (steel part)
(1) Multi-reinforced concrete 1:Hot-rolled steel bars with fat strips for reinforced concrete (GB11499-1998) (2) Hot-rolled round steel bars for reinforced concrete (GB13013-91) (3) Residual heat treated steel bars for reinforced concrete (GR13014-91) (4) Heat treated steel bars for prestressed concrete (GB4463-84) (5) Steel wire for prestressed concrete (GB/T5223-1995) (6) Steel strand for prestressed concrete (GB B/T5224--1995) (7) "Low Carbon Steel Hot-rolled Circular Wire" (GB701-97) (8) "Cold-rolled Ribbed Steel Bar" (CB13788-92) (9) & Cold-drawn Cold-rolled Low Carbon Threaded Wire for Concrete Products (FC/T540-94) (10) "Steel Strand, Steel Wire Bundle Unbonded Prestressed Reinforcement" (JG3006-93) (11) "Low Alloy Steel Wire for Prestressed Filter Concrete" (YB/T038-93) Steel Part
(12) Carbon Structural Steel (G3700-88) (13) Low Alloy High Strength Structural Steel (GH/T1591-94) (14) Technical Specifications for Carbon Steel and Low Alloy Steel Plates for Bridge and Beam Construction (YB168-70) 198
Part I Testing Methods and Standards for Major Building Materials (15) Technical Specifications for High Quality Carbon Structural Steel (GB69988) (16) General Provisions for Acceptance, Packaging, Marking and Quality Certificate of Steel Plates and Strips (GB247-97) (17) Cast Carbon Steel for General Engineering (GB5676-85) (18) Structural Steel for Bridges (YB(T)10) (19) Dimensions, Shapes, Weights and Permissible Deviations of Hot-rolled Equal Angle Steel (GB9787-88) (20) Dimensions, Shapes, Weights and Permissible Deviations of Hot-rolled Unequal Angle Steel (GB9788-88) (21 ) "Dimensions, shape, weight and allowable deviations of hot-rolled round steel and square steel" (GB702-86) (22) "Dimensions, shape, weight and allowable deviations of hot-rolled flat steel" (GB704-88) (23) "Dimensions, shape, weight and allowable deviations of hot-rolled hexagonal and octagonal steel" (GB705-89) (24) "Dimensions, shape, weight and allowable deviations of hot-rolled I-beams" (GH706-88) (25) "Dimensions, shape, weight and allowable deviations of hot-rolled channel steel" (GB707-88) (26) "Dimensions, shape, weight and allowable deviations of cold-rolled steel plates and strips" (GH708-88) (27) "Dimensions, shape, weight and allowable deviations of hot-rolled steel plates and strips" (GB709-88) (28) "Dimensions, shape, weight and allowable deviations of hot-rolled L-shaped steel" (GB9946-88) (29) "Dimensions, shape, weight and allowable deviations of hot-rolled H-shaped steel" (GH112 6398) (30) "Architectural Corrugated Steel Plate" (GB/T12755-91) (31) "Hot-rolled Ordinary L-shaped Steel" (YB(T)56-87) (32) "Hot-rolled No. 8 Light I-shaped Steel" (YB(T)65-87) [33] "Technical Specifications for Cold-formed Steel" (GH6725-92) (34) "Dimensions, Shape, Weight and Permissible Deviations of General Cold-formed Open-shaped Steel" (GB6723-86) (35) "Carbon Turbulence Hot-rolled thick plates and strips of structural steel and low-alloy structural steel" (GB3274--88) 2. Excerpt of main technical performance indicators of steel (products) for construction Steel bars part
(1) Main technical properties of hot-rolled ribbed steel bars for reinforced concrete (GB1499-1998) 1) Mechanical properties
The mechanical properties of steel bars shall comply with the requirements of Table 2-1, (dpo.2)
HRE335
IIRE 4n0
HRR500
Metric diameter
6 --25
28 50
6·-25
28 - 50
Not less than
Table 2-1
() The total elongation of steel bars under maximum force3 shall not be less than 2.5%. If the supplier can guarantee, no inspection is required. ② According to the requirements of the purchaser, steel bars that meet the following conditions can be supplied: z) The ratio of the actual tensile strength of the steel bar to the actual yield point is not less than 1.25; II. Construction steel materials
6) The ratio of the actual yield point of the steel bar to the minimum yield point specified in Table 5 is not greater than 1.30. 2) Process performance
After bending 18(\ according to the bending diameter specified in Table 22, no cracks shall occur on the surface of the bent part of the steel bar. Brand convex
HRB333
HRB400
Nominal diameter
2月:-50
6 -- 25
28- 50
②Reverse bending performance
Flexure test
Core diameter
HRA500
According to the requirements of the purchaser, the steel bar can be subjected to reverse bending performance test, nominal diameter
6-·25
28 --50
Table 2-2
Flexure test
Core diameter
The core diameter of the reverse bending test is increased by one steel bar diameter compared with the bending test. First bend forward 45° and then bend reversely 23°. After the reverse bending test, no cracks shall occur on the surface of the steel bar at the bending part. 3) Grade and chemical composition
(①) The grade of steel shall comply with the provisions of Table 2-3, and its chemical composition and carbon content (melting analysis) shall not be greater than the values ​​specified in 2-3. According to the needs, V, Nb, T: and other elements can be added to the steel. Chemical composition HRB335 HRR400 JHRE500 ② The chemical composition and range of each grade of steel bars can be referred to Table 2-4. ) Carbon equivalent Ceg (%) value can be calculated according to formula (1): % Ceq = C + Mn/6 + (Ct + V + Mo) /5 + (Cu + Ni)/15 2-3 ④ The nitrogen content of steel should not exceed 0.012%. If the supplier can guarantee it, no analysis is required. If there is a sufficient amount of nitrogen-binding elements in the steel, the nitrogen content limit can be appropriately relaxed. @The allowable deviation of the chemical composition of the steel bar shall comply with the provisions of (B/T222. The allowable deviation of carbon content is +0.U3%. The reference chemical composition (melting analysis) of HRB335 and HRB400 steel bars is shown in Table 2-4. Table 2-4
HRB335
Original grade
20MnSi
20MnSiV
Chemical composition
0.17.0.250.40-0.80,7.20--1.600.17 ~0.250.20-0.80|1.2n--1.60|0.04 --0.12HRH 4I20MnSNbIG.17 --(0.25/0.20-0.60 1203 --1.60)
20MnT10.17--0.250.17.0.37
1.20--1.60
10.02 ~ 0.04
0.02-0.0s0.0450.045
Part I Testing Methods and Standards for Main Building Materials4) Surface Quality
There shall be no cracks, scars or broken stools on the surface of the steel bars. The steel bar surface is allowed to have bulges, which shall not exceed the height of the transverse ribs. The depth and height of other defects on the steel bar surface shall not exceed the allowable deviation of the size of the part where they are located. 5) Inspection Items
The inspection items, sampling methods and test methods of each batch of steel bars shall comply with the provisions of Table 2-5. Table 2-5 Inspection items Chemical analysis (olefin analysis) Reverse bending Weight bias pad Sampling number Sampling method GVT222 Cut two copper bars at random Two bars can be cut as required According to 7.4 of this standard Test method GR/T223 GIVT4336 ( Note: When there is a dispute over the results of chemical analysis and tensile test, the arbitration test shall be carried out in accordance with CB/T223 and GH/T228. (2) Main technical properties of hot-rolled round steel bars for reinforced concrete (GB13013-91) 1) Mechanical properties, process properties
Continuation of standard 7.4
The mechanical properties and process properties of the steel bar shall comply with the provisions of Table 2-6. No cracks shall occur on the outer surface of the bending part during the cold bending test.
Bending point
Soft surface
Forging type of steel bar
Group strength grade code
2) Grade and chemical composition
Nominal commercial inspection
Tensile strength
a(MTa)
The grade and chemical composition (melting analysis) of steel shall comply with the provisions of Table 2-7. Surface shape
Rebar crack type
Strength code
Heat
8s (%)
Chemical content (%)
lo.14-0.220.12-0.300.300.65
Table 2-6
·Core diameter
Rebar nominal diameter
180\d = a
Table 2-7
Note: 1. The content of residual elements such as nitrogen, nitrate and copper in steel should not exceed 0.30% respectively. The nitrogen content of oxygen converter steel should not exceed 0.08%. With the same requirements, the residual copper content can be less than 0.35%. If the supplier can guarantee it, no analysis is required. 2. The residual content of tantalum in steel should not be greater than 0.080%. For steel smelted with tantalum containing tantalum, the content of tantalum shall be agreed upon by both parties. If there is a combination of raw materials, the content of tantalum in steel may not be analyzed. 3. The allowable difference in the chemical composition of steel sieves shall comply with the relevant provisions of GB222: 4. Under the condition of ensuring that the steel is qualified, the lower limit of the steel composition shall not be a delivery object. 3) Inspection items, sampling quantity and method
The inspection items, sampling methods and test methods of each batch of steel bars shall comply with the provisions of Table 2-8. Sequence
Inspection Items
Chemical Analysis
Weight Deviation
Number of Samples
This Standard6.4
II. Steel for Construction
Sampling Method
GI3 222
Cut Any Root of Steel Bar
Cut Any Two Steel Bars
This Standard6.4
Dec. 2-8
Test MethodwwW.bzxz.Net
GB 228This Standard6.2
GB232, This Standard6.2
This Standard2.3
This Standard6.4
Each batch should be composed of steel bars of the same brand, same furnace number, same specification and same delivery status. The weight of each batch shall not exceed 60t. (3) Main technical properties of residual heat treated steel bars for petal reinforced concrete (GE13014-91) 1) Mechanical properties and process properties
The mechanical properties and process properties of steel bars shall comply with the requirements of Table 2-9. During the cold bending test, no cracks shall occur on the outer surface of the bending part.
Tensile strength
Strength grade
Surface shape
Crescent
Interpretation level
Nominal diameter
Service point
a,(MPa)
Less than
Elongation
Table 2-9
Core diameter
Nominal diameter of steel shears
9u°d-3a
Note: With the consent of the purchaser, when the full performance of KL40Ⅱ steel meets the requirements of Table 5 and the elongation cold test meets the requirements of Ⅱ bars in Table 6 of GB1499. RL335Ⅱ steel can be delivered. This should be noted in the quality certificate. 2) Brand and chemical composition
The brand and chemical composition (melting analysis) of steel should meet the requirements of Table 2-10. Chemical content (%)
Long surface shape
Use tooth rib
Rebar grade
Steel code
20MnSi
0.170.25;0.40~0.801.201.60
Table 2-10
Not more than
0.0450.045
Note: 1. In the steel grade, the residual content of tin and copper should not exceed 0.30% respectively, and the total amount should not exceed 0.60%. With the consent of the buyer, the residual content of other metals may not exceed 0.35%. The supplier guarantees that no analysis is required.
2. The nitrogen content of oxygen converter steel should not exceed 0.008%, and the content of nitride smelted by oxygen blowing process may not exceed 0.012%. The supplier guarantees that no analysis is required.
3. The allowable deviation of the chemical composition of steel bars shall comply with the provisions of GB222. 3) Inspection items, sampling quantity and methods
The inspection items, sampling methods and test methods for each batch of steel bars shall comply with the provisions of Table 2-11. Inspection items
Chemical composition
Weight tolerance
Sampling method
Gl 222
Sampling of any two steel bars
Sampling of any two steel bars
According to 6.4 of this standard
Sampling quantity
According to 6.4 of this standard
Table 2-11
Test method
GB228, 6.2 of this standard
GB232, 6.2 of this standard
6.3 of this standard
6.4 of this standard
Part 1: Testing methods for main building materials Standard Each batch of steel bars shall be composed of steel bars of the same brand, same furnace number, same specification and same delivery status. The weight of each batch shall not exceed 60t. (4) Main technical properties of prestressed concrete reinforcement bars (GI34463-84) 1) Mechanical properties The mechanical properties of steel shall comply with the requirements of Table 2-12. Short eye strength 00.2 Nominal diameter 4U Si2Mn 48 Si2Mn 45 Si2C (N/mm2) Tensile strength (N/rurt) Table 2-12 Tensile strength 10 Note: 1. According to the requirements of the buyer, the supplier can provide the relaxation performance of the same product. 2. Relaxation performance: The relaxation value of 1UKX0% is not more than 3.5%. On the basis of ensuring that the 10h looseness value is qualified, a 10h looseness test can be carried out, and the looseness value should not be greater than 1.5%. 2) Brand and chemical composition The brand and chemical composition (melting analysis) of the steel should comply with the requirements of Table 2-13. Chemical
40S2Mn
48S2Mm
0.36~0.45
1.40--1.90
0.44--0.53
0.41-0.51
1.401 --1.90
1.55--1.95
.5]--1.20
0.80--1.20
0.40~0.70
0,30 --0.60
Table 2-13
Note: 1.40Si2Mn, 48Si2Mn The residual content of Cr and Ni shall not be greater than 0.20% respectively, and the residual content of Cu shall not be less than 0.30%. The residual content of Ni and Cu in 45Si2Cr steel shall not be greater than 0.30% respectively. The supplier may not conduct residual element analysis, but shall ensure that it complies with the above provisions. 2. The allowable deviation of the chemical composition of the product and the melting analysis composition shall comply with the relevant provisions of "Technical Conditions for Low Alloy Structures" (GB1591-94). The allowable deviation of Cr in the finished product shall not be greater than +0.05%. 3) Inspection items, sampling quantity and method
① Steel bars shall be inspected in batches. Each batch shall consist of steel bars with the same cross-sectional dimensions, the same heat treatment system and the same furnace number, and the weight of each batch shall not exceed 60t.
② 10% of the coils (not less than 25 coils) shall be selected from each batch of steel bars for mechanical property test. If one item fails in the test results, the unqualified coil shall be reported. Double the number of samples shall be taken from the steel bars that have not been tested for retesting. If there is still one item that fails, the coil shall be regarded as unqualified, but the supplier may reclassify it and submit it as a new batch for acceptance. ③ 10% of the coils (not less than 25 coils) shall be selected from each batch of steel bars for surface quality and dimensional deviation inspection. If the inspection fails, the batch of steel bars shall be inspected coil by coil. ① Relaxation test. The ambient temperature of the test piece shall be kept within the range of (20±2)C, and the test piece shall not be subjected to any heat treatment or cold processing after preparation. During the relaxation test, the initial load applied to the steel bar shall be equal to 70% of the tensile strength of the steel bar specified in Table 2-12 multiplied by the calculated area of ​​the steel bar; the initial load shall be applied evenly within 5 minutes and maintained for 2 minutes before recording the relaxation value.
(5) Main technical properties of steel wire for prestressed concrete (GB/T5223-95) 1) Mechanical properties
(D) The mechanical properties of stress-relieving steel wire shall comply with the provisions of Table 2-14. The mechanical properties of stress-relieving steel wire
Tensile strength
Nominal diameter
(rmas)
shall not be less than
The specified non-ratio
Length should
Elongation ratio
f fn=
1Hrrum)
wood trunk
bending times
times/180\
not less than
bending radius
: 1. Grade relaxation means all pass the inspection! Grade relaxation means low relaxation. They are applicable to all steel wires. 2. The instantaneous strength m2 value is not less than 85% of the nominal tensile strength: Construction steel
the initial stress is equivalent to
the percentage of the nominal tensile strength (%)
Table 2-14
1000) stress declaration
not more than||tt t||What kind of looseness
[Grade of powder relaxation
3. The elongation in Table 1 is recommended to be L. -210run The elongation under the maximum load shall not be less than 3.5%. Unless otherwise specified by the manufacturer, the elastic modulus is (205110 yuan% a, but it is not included in the delivery.②The mechanical properties of cold-drawn steel wire shall comply with the provisions of Table 2-15. The size and mechanical properties of cold-drawn steel wire
Nominal diameter
Anti-grain tension
(MPa) shall not be less than"
Specified non-standard
Law elongation stress.
Not less than
Elongation
(1-, = 100mmm)
not less than
Table 2-15
Test bending times
Times 180
not less than
Bending radius
This: 1. The specified non-proportional elongation should be force. The value of 42 should not be less than 75% of the nominal tensile strength. 2. The bending test of 3.00mm key wire in the table can also be carried out according to the uniform bending radius R-10mm, and the number of test bending times should not be less than 9 times. ③The mechanical properties of notched steel wire should comply with the provisions of Table 2-16. Mechanical properties of notched steel wire
Elongation
Interference strength
Nominal diameter
.5. 00
Not less than
Specified non-proportional elongation stress
Not less than
Not less than
Bending number
180
Not less than
Note: The specified non-proportional elongation stress is not less than 85% of the nominal tensile strength. Bending radius
The quotient of the initial stress equal to the nominal tensile strength (%)
1000h stress loss (%)
Not more than
I
II Assuming relaxation
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