GB/T 3098.7-2000 Mechanical properties of fasteners Self-extruding screws
Some standard content:
GB/T 3098.7—2000
This standard is equivalent to the international standard ISO7085:1999 "Mechanical and working performance requirements for surface hardened and tempered metric self-threading screws".
GB/T3098 is generally titled "Mechanical properties of fasteners" and includes the following parts: Bolts, screws and studs
GB/T 3098.1—2000
Mechanical properties of fasteners
-GB/T 3098.2—2000\
Mechanical properties of fasteners
GB/T 3098.3—2000
GB/T 3098. 4—2000
GB/T 3098.5—2000
--GB/T 3098.6—-2000
GB/T 3098.7—2000
-GB/T 3098.8—-1992
GB/T 3098.9—1993
GB/T 3098.10-1993
GB/T 3098.11
Mechanical properties of fasteners
Mechanical properties of fasteners
Mechanical properties of fasteners
Mechanical properties of fasteners
Mechanical properties of fasteners
Mechanical properties of fasteners
Mechanical properties of fasteners
Mechanical properties of fasteners
GB/T 3098. 12-1996
-- GB/T 3098. 13-
-GB/T 3098.14-
GB/T3098.15—2000
-GB/T3098.16-—2000
GB/T3098.17-
Nut coarse thread
Set screw
Nut fine thread
Self-tapping screw
Stainless steel bolts, screws and studs
Self-extruding screws
Heat-resistant threaded connection pairs
Effective torque steel hexagonal locking nuts
Bolts, screws, studs and nuts made of non-ferrous metalsSelf-drilling and self-tapping screws
Nut cone proof load test
Mechanical properties of fasteners
Mechanical properties of fasteners
Torque test and breaking torque of bolts and screws Nominal diameter 1~10 mm
Mechanical properties of fasteners
Mechanical properties of fasteners
Mechanical properties of fasteners
Mechanical properties of fasteners
ISO7085 does not specify the content of Note 1) (Chapter 1). Nut expansion test
Stainless steel nuts
Stainless steel set screws
Preload test for hydrogen embrittlement inspection
Parallel bearing surface method
This standard is a revision of GB/T3098.7-1986. The main revisions are as follows: a) Modify the name of the standard;
b) Cancel the mechanical property grades classified by material and the material grades for reference (Table 1); c) Add the provisions of "core hardness after re-extinguishing" (Table 2, 4.9 and 5.8); d) Cancel the provisions of "anti-hydrogen embrittlement torque" and quote the provisions of GB/T3098.17 (Table 2, 4.8 and 5.7); e) Adjust the provisions of "breaking torque" (Table 2, Table 3, 4.5 and 5.4) ; f) Add the provision of "minimum tempering temperature is 340℃" (Article 4.2); g) Adjust the "core hardness index (Article 4.3); h) The bevel angle of the head solidity test is increased to 7° (Articles 4.6, 5.5 and Figure 4); i) "The breaking tensile load is changed to a reference value, and the test shall be carried out only after the agreement between the supply and demand parties (Table 3 and Article 4.10); j) Add the provisions of marking (Chapter 7); k) Cancel the old standard Appendix A Prefabricated holes for self-drilling locking screws (reference parts). This standard replaces GB/T3098.7-1986 from the date of implementation. This standard is proposed by the State Machinery Industry Bureau. This standard is under the jurisdiction of the National Fastener Standardization Technical Committee. This standard is under the responsibility of the Mechanical Science Research Institute, China Aerospace Standardization Institute, Shanghai Standard Parts Factory No. 10, Beijing Standard Parts Industry Group Corporation, Haiyan Yonggu Tools and Dies Co., Ltd., Shanghai Fastener and Welding Materials Technology Research Institute and Shenzhen Aviation Standard Parts Co., Ltd. participated in the drafting.
This standard is interpreted by the Secretariat of the National Technical Committee for Standardization of Fasteners. 143
GB/T3098.7-2000
ISO Foreword
ISO (International Organization for Standardization) is a worldwide joint organization of national standards bodies (ISO member bodies) in various countries. The formulation of international standards is usually carried out through ISO's various technical committees. Each member group may also participate in the committee if it is interested in the project carried out by a technical committee. Governmental and non-governmental organizations related to ISO International organizations may also take part in this work. ISO) has close links with the International Electrotechnical Commission (IEC) in the field of electrotechnical standardization. The drafting of international standards shall be carried out in accordance with the rules given in the ISO/IEC Guides, Part 3. Draft international standards adopted by the technical committee are circulated to all member bodies for voting. Formal publication of international standards requires approval by at least 75% of the member bodies casting a vote.
International Standard ISO7085 was prepared by ISO/TC2 Technical Committee SC1, Mechanical Properties of Fasteners, Subcommittee SC1. 144
1 Scope
National Standard of the People's Republic of China
Mechanical Properties of Fasteners
Self-clinching Screws
Mechanical properties of fastenersThread rolling screwsbZxz.net
GB/T_3098.7—-2000
idt IsO 7085:1999
Replaces GB/T3098.7—1986
This standard specifies the technical requirements for surface hardened and tempered self-extruding screws\. The self-extruding screws that meet this standard can extrude a variety of common (internal) threads with a thread diameter of 2~～12 mm and are used for electromechanical products. GB/T3098.1 is not applicable to screws manufactured according to this standard. 2 Reference standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB/T197—1981 Tolerances and fits for common threads (diameter 1~355mm) GB/T709-1988 Dimensions, shapes, weights and permissible deviations of hot-rolled steel sheets and strips GB/T3098.2-2000 Mechanical properties of fasteners Coarse pitch threads for nuts (idtISO898-2:1992) GB/T 3098.17-2000
GB/T4340.1—1999
Mechanical properties inspection of fasteners Preload test for hydrogen embrittlement Parallel bearing surface method
(idt ISO 15330:1999)
Metal Vickers hardness test
GB/T5267—1985 Electroplated coatings on threaded fasteners Part 1: Test methods (eqvIS06507-1:1997) GB/T 6559--1986
'Self-drilling screws Coarse pitch common thread series ISO10683:2000 Fasteners Electroless zinc powder coating 3 Materials
Self-drilling screws shall be made by cold heading of carburized steel. The chemical composition of the materials given in Table 1 is for guidance only. Table 1 Chemical composition
0.15~0.25
0.13~0.27
Composition limit, %
0. 70~1. 65
Note: If the ineffective boron is controlled by adding titanium and (or) aluminum, the boron content can reach 0.005% 4 Mechanical and working properties
4.1 Items
Mechanical and working properties Items and corresponding test methods are shown in Table 2. 1) Including white tapping locking screws with arc-shaped triangular cross-sections of the screw that meet the requirements of GB/I6559. Approved by the State Administration of Quality and Technical Supervision on September 26, 2000 0.64~1.71
Implemented on February 1, 2001
Performance items
Core hardness
Surface hardness
Carburized layer depth
Failure torque
Head firmness
Tightening performance
Hydrogen embrittlement resistance
Core hardness after re-tempering
Failure tensile load
4.2 Heat treatment
GB/T 3098.7—2000
Table 2 Mechanical and working performance items
Technical requirements (items or tables)
4.4, Table 4
4.5, Table 3
4. 7, Table 3
4.10, Table 3
Test methods (items)
The finished screws shall be subjected to surface quenching and tempering treatment. The minimum tempering temperature is 340℃, and shall meet the various mechanical and working performance requirements specified in Table 3.
Nominal thread diameter
4.3 Hardness
Destructive torque
Mechanical and working performance requirements
Insertion torque
The core hardness shall be 290～370HV10, and the minimum surface hardness shall be 450HV0.3. Surface carburized layer depth
The surface carburized layer depth shall meet the requirements of Table 4. Table 4 · Depth of surface carburized layer
Nominal diameter of thread
10, 12
4.5 Breaking torque
Depth of surface carburized layer
Breaking tensile load (reference)
When the test is carried out in accordance with the provisions of Article 5.4, the breaking torque shall comply with the provisions of Table 3. The fracture shall not occur in the clamped threaded part. 4.6 Head firmness
When the test is carried out in accordance with the provisions of Article 5.5, when the bearing surface under the screw head is permanently deformed and the angle between it and the plane perpendicular to the screw axis reaches 7\, no cracks shall appear at the junction of the head and the shank. As long as the screw head is not broken, even if it breaks at the first thread, the test shall still be judged as qualified.
4.7 Ability of thread extrusion
GB/T3098.7—2000
A screw with no permanent deformation of the thread (checked under a 10x magnifying glass) shall be able to extrude a matching internal thread on the test plate specified in 5.6. During the process of extruding the thread, the screw-in torque shall not exceed the screw-in torque value specified in Table 3. The internal thread formed by screw extrusion on the test plate shall be able to be screwed into an external thread fastener with a thread conforming to GB/T197 and a tolerance band of 6h, and be able to withstand the guaranteed load of performance level 8 specified in GB/T3098.2. 4.8 Resistance to hydrogen embrittlement
Self-extruding screws, especially electroplated self-extruding screws, tend to fracture due to hydrogen embrittlement. Therefore, the process shall be reviewed according to the hydrogen embrittlement test (parallel bearing surface method) specified in GB/T3078.17 to ensure that the process related to hydrogen embrittlement is under control. Once hydrogen embrittlement is found, the process must be improved.
After electroplating, the screws shall be driven out of hydrogen according to the provisions of GB/T5267. Note: It is better to apply non-electrolytic zinc powder coating according to the provisions of ISO10683. 4.9 Core hardness after tempering
According to the method described in Article 5.8, the reduction value of the core hardness measured after tempering shall not exceed 20HV. 4.10 Destructive tensile load
Screws with a length of ≥12mm. or ≥3d can be subjected to tensile test after agreement between the supplier and the buyer. Note: The destructive tensile load given in Table 3 is for reference only. 5 Test method
5.1 Core hardness test
The core hardness shall be measured at the 1/2 radius of the cross section of the screw. The section shall be away from the end and pass through the thread minor diameter. The test shall be carried out in accordance with the provisions of GB/T4340.1.
5.2 Surface hardness test
For routine testing, the surface hardness can be measured at the end, shank or head of the screw (as long as the depth of the surface carburized layer and the geometric shape of the screw allow), see Figure 1. The test method is in accordance with GB/T4340.1. The hardness test should be carried out after the coating is removed. For arbitration tests, for screws with a nominal thread diameter ≥4mm, a Vickers microhardness tester (test force HVo.1) should be used. The measurement should be carried out on the tooth profile of the longitudinal section specimen, at a distance of at least 0.05mm from the edge of the specimen. For screws with a nominal thread diameter <4mm, the test conditions should be determined through negotiation.
Figure 1 Measurement location of surface hardness
5.3 Surface carburized layer depth test
Surface carburized layer depth is the distance from the surface to a point perpendicular to the surface, the hardness of which is the actual hardness of the core plus 30HV0.3.
In arbitration test, a microhardness tester should be used with a test force of HVo.3. The preparation of metallographic specimens is shown in Figure 2. 1) Only for incomplete carburization of thread profile. Figure 2 Measurement location of surface carburized layer depth
5.4 Destructive torque test
GB/T 3098.7--2000
Fix the screw specimen firmly into the fixture by appropriate means, see Figure 3. It should be ensured that at least two complete threads are clamped in the fixture, and at least two complete threads are left outside the fixture. In addition, use a calibrated and suitable measuring device to apply torque to the screw until the screw fails. Record the torque value when the screw fails. The value shall comply with the provisions of Table 3.
1-Die
Figure 3 Typical torque test device
5.5 Head firmness test
Insert the screw specimen into the hole of the wedge (or other suitable fixture). Hole diameter: For screws ≤M6, the hole diameter is the nominal thread diameter plus 0.05mm; for screws >M6 to M12, the hole diameter is the nominal thread diameter plus 0.1mm. Apply axial pressure to the screw until the head bearing surface is in contact with the inclined surface (the angle between the head bearing surface and the vertical surface of the screw axis is 7°), see Figure 4. This test is not applicable to countersunk screws.
Note: Usually, a suitable hand hammer is used to hit once or several times to achieve 7 permanent deformation. 1 Wedge: 2 Pressure load
Figure 4 Head firmness test
5.6 Tightening performance test
The tightening performance test can show the ability to extrusion form threads in steel parts. Screw the screw specimen into the test plate (see Figure 5 for dimensions) until at least one thread (except the end of the screw) protrudes from the test plate. When starting to squeeze the thread, use axial force: for screws ≤M5, the maximum axial force Fmax-50N; for screws ≥M5, the maximum axial force Fmm×—100 N.
GB/T3098.7—2000
During the arbitration test, the tightening speed should not exceed 0.5s-1 (30r/min). The maximum torque that occurs during the test is the screw-in torque. Lubricant can be added to achieve the specified screw-in torque. The test plate should be made of low-carbon rolled steel plate with a hardness of 140~~180HV30. The thickness of the test plate should be equal to the nominal diameter of the screw thread, and the hole diameter should be as specified in Table 5.
Nominal thread diameter
Thickness and hole diameter of the test plate
Note: The thickness tolerance of the test plate should comply with the provisions of GB/T709 (rolled steel plate). 5.7 Hydrogen embrittlement resistance test
Hydrogen embrittlement resistance test See GB /T3098.17.
5.8 Re-tempering test
Before and after the re-tempering test (temperature 330℃, insulation for 1h), the difference in the average hardness of the three points of the core of the same screw should not be greater than 20HV. This test is not mandatory and is only applicable to arbitration tests in case of disputes. 5.9 Tensile test
Install the screw specimen on the tensile testing machine, and ensure that at least 6 threads are exposed during installation. Apply axial load to the screw until the screw breaks. During the test, the moving speed of the chuck should not exceed 25m m/min. To prevent the specimen from being subjected to lateral loads, the chuck of the testing machine should be able to automatically center. The fracture should occur at the rod or threaded portion, and should not occur at the junction of the nail head and the rod. 6 Torque wrench
The measurement error of the torque wrench used in the torque test and screw-in performance test should be within ±3% of the specified torque value. A power device that can display torque with equivalent accuracy can also be used. A manual torque wrench should be used for arbitration tests. 7 Marking
Sign symbol
Marking for surface-hardened and tempered self-extruding screws The symbol is "-○-". 7.2 Identification
Surface hardened self-extruding screws shall be marked with concave or convex marks according to the symbols specified in Article 7.1. For hexagonal head screws or hexalobular head screws with a nominal thread diameter ≥ 5mm, the mark must be made and should be made on the nail head as much as possible. With the agreement between the supplier and the buyer, other types of surface hardened and tempered self-extruding screws may also use the above marks. 7.3 Trademark (Identification) Mark
For all products that require the production of marking symbols, it is mandatory to mark the trademark or manufacturer's identification mark. 1493 Hardness
Failure torque
Mechanical and working performance requirements
Insertion torque
The core hardness should be 290~370HV10, and the minimum surface hardness should be 450HV0.3. Surface carburized layer depth
Surface carburized layer depth should comply with the provisions of Table 4. Table 4 Surface carburized layer depth
Nominal thread diameter
10, 12
4.5 Failure torque
Surface carburized layer depth
Failure tensile load (reference)
When tested in accordance with the provisions of 5.4, the failure torque shall comply with the provisions of Table 3. Fracture shall not occur in the clamped threaded part. 4.6 Head strength
When tested in accordance with the provisions of 5.5, when the bearing surface under the screw head is permanently deformed and the angle between it and the plane perpendicular to the screw axis reaches 7\, no cracks shall appear at the junction of the head and the shank. As long as the screw head is not broken, even if it breaks at the first thread, the test should still be judged as qualified.
4.7 Ability of thread extrusion
GB/T3098.7—2000
A screw with no permanent deformation of the thread (checked under a 10x magnifying glass) should be able to extrude a matching internal thread on the test plate specified in Article 5.6. During the process of extruding the thread, the screwing torque should not exceed the screwing torque value specified in Table 3. The internal thread extruded by the screw on the test plate should be able to be screwed into an external thread fastener with a thread that complies with GB/T197 and a tolerance band of 6h, and can withstand the guaranteed load of performance level 8 specified in GB/T3098.2. 4.8 Hydrogen embrittlement resistance
Self-extruding screws, especially those that have been electroplated, tend to fracture due to hydrogen embrittlement. Therefore, the process should be reviewed according to the hydrogen embrittlement test (parallel bearing surface method) specified in GB/T3078.17 to ensure that the process related to hydrogen embrittlement is under control. Once hydrogen embrittlement is found, the process must be improved.
The electroplated screws should be hydrogen-driven according to the provisions of GB/T5267. Note: It is better to apply non-electrolytic zinc powder coating according to the provisions of ISO10683. 4.9 Core hardness after tempering
According to the method described in Article 5.8, the reduction in the core hardness measured after tempering should not exceed 20HV. 4.10 Destructive tensile load
Screws with a length of ≥12mm. or ≥3d can be subjected to tensile test by agreement between the supplier and the buyer. Note: The destructive tensile load given in Table 3 is for reference only. 5 Test method
5.1 Core hardness test
The core hardness shall be measured at the 1/2 radius of the screw cross section. This section shall be away from the end and pass through the thread minor diameter. The test shall be carried out in accordance with the provisions of GB/T4340.1.
5.2 Surface hardness test
During routine testing, the surface hardness can be measured at the end, shank or head of the screw (as long as the depth of the surface carburized layer and the geometric shape of the screw allow), see Figure 1. The test method shall be in accordance with the provisions of GB/T4340.1. The hardness test shall be carried out after the coating is removed. During arbitration testing, for screws with a nominal thread diameter ≥4mm, a Vickers microhardness tester (test force HVo.1) shall be used. The measurement shall be carried out on the tooth profile of the longitudinal section specimen at a distance of at least 0.05mm from the edge of the specimen. For screws with a nominal thread diameter <4mm, the test conditions shall be determined by negotiation.
Figure 1 Measurement location of surface hardness
5.3 Surface carburized layer depth test
Surface carburized layer depth is the distance from the surface to a point perpendicular to the surface, the hardness of which is the actual hardness of the core plus 30HV0.3.
In arbitration test, a microhardness tester should be used with a test force of HVo.3. The preparation of metallographic specimens is shown in Figure 2. 1) Only for incomplete carburization of thread profile. Figure 2 Measurement location of surface carburized layer depth
5.4 Destructive torque test
GB/T 3098.7--2000
Fix the screw specimen firmly into the fixture by appropriate means, see Figure 3. It should be ensured that at least two complete threads are clamped in the fixture, and at least two complete threads are left outside the fixture. In addition, use a calibrated and suitable measuring device to apply torque to the screw until the screw fails. Record the torque value when the screw fails. The value shall comply with the provisions of Table 3.
1-Die
Figure 3 Typical torque test device
5.5 Head firmness test
Insert the screw specimen into the hole of the wedge (or other suitable fixture). Hole diameter: For screws ≤M6, the hole diameter is the nominal thread diameter plus 0.05mm; for screws >M6 to M12, the hole diameter is the nominal thread diameter plus 0.1mm. Apply axial pressure to the screw until the head bearing surface is in contact with the inclined surface (the angle between the head bearing surface and the vertical surface of the screw axis is 7°), see Figure 4. This test is not applicable to countersunk screws.
Note: Usually, a suitable hand hammer is used to hit once or several times to achieve 7 permanent deformation. 1 Wedge: 2 Pressure load
Figure 4 Head firmness test
5.6 Tightening performance test
The tightening performance test can show the ability to extrusion form threads in steel parts. Screw the screw specimen into the test plate (see Figure 5 for dimensions) until at least one thread (except the end of the screw) protrudes from the test plate. When starting to squeeze the thread, use axial force: for screws ≤M5, the maximum axial force Fmax-50N; for screws ≥M5, the maximum axial force Fmm×—100 N.
GB/T3098.7—2000
During the arbitration test, the tightening speed should not exceed 0.5s-1 (30r/min). The maximum torque that occurs during the test is the screw-in torque. Lubricant can be added to achieve the specified screw-in torque. The test plate should be made of low-carbon rolled steel plate with a hardness of 140~~180HV30. The thickness of the test plate should be equal to the nominal diameter of the screw thread, and the hole diameter should be as specified in Table 5.
Nominal thread diameter
Thickness and hole diameter of the test plate
Note: The thickness tolerance of the test plate should comply with the provisions of GB/T709 (rolled steel plate). 5.7 Hydrogen embrittlement resistance test
Hydrogen embrittlement resistance test See GB /T3098.17.
5.8 Re-tempering test
Before and after the re-tempering test (temperature 330℃, insulation for 1h), the difference in the average hardness of the three points of the core of the same screw should not be greater than 20HV. This test is not mandatory and is only applicable to arbitration tests in case of disputes. 5.9 Tensile test
Install the screw specimen on the tensile testing machine, and ensure that at least 6 threads are exposed during installation. Apply axial load to the screw until the screw breaks. During the test, the moving speed of the chuck should not exceed 25m m/min. To prevent the specimen from being subjected to lateral loads, the chuck of the testing machine should be able to automatically center. The fracture should occur at the rod or threaded portion, and should not occur at the junction of the nail head and the rod. 6 Torque wrench
The measurement error of the torque wrench used in the torque test and screw-in performance test should be within ±3% of the specified torque value. A power device that can display torque with equivalent accuracy can also be used. A manual torque wrench should be used for arbitration tests. 7 Marking
Sign symbol
Marking for surface-hardened and tempered self-extruding screws The symbol is "-○-". 7.2 Identification
Surface hardened self-extruding screws shall be marked with concave or convex marks according to the symbols specified in Article 7.1. For hexagonal head screws or hexalobular head screws with a nominal thread diameter ≥ 5mm, the mark must be made and should be made on the nail head as much as possible. With the agreement between the supplier and the buyer, other types of surface hardened and tempered self-extruding screws may also use the above marks. 7.3 Trademark (Identification) Mark
For all products that require the production of marking symbols, it is mandatory to mark the trademark or manufacturer's identification mark. 1493 Hardness
Failure torque
Mechanical and working performance requirements
Insertion torque
The core hardness should be 290~370HV10, and the minimum surface hardness should be 450HV0.3. Surface carburized layer depth
Surface carburized layer depth should comply with the provisions of Table 4. Table 4 Surface carburized layer depth
Nominal thread diameter
10, 12
4.5 Failure torque
Surface carburized layer depth
Failure tensile load (reference)
When tested in accordance with the provisions of 5.4, the failure torque shall comply with the provisions of Table 3. Fracture shall not occur in the clamped threaded part. 4.6 Head strength
When tested in accordance with the provisions of 5.5, when the bearing surface under the screw head is permanently deformed and the angle between it and the plane perpendicular to the screw axis reaches 7\, no cracks shall appear at the junction of the head and the shank. As long as the screw head is not broken, even if it breaks at the first thread, the test should still be judged as qualified.
4.7 Ability of thread extrusion
GB/T3098.7—2000
A screw with no permanent deformation of the thread (checked under a 10x magnifying glass) should be able to extrude a matching internal thread on the test plate specified in Article 5.6. During the process of extruding the thread, the screwing torque should not exceed the screwing torque value specified in Table 3. The internal thread extruded by the screw on the test plate should be able to be screwed into an external thread fastener with a thread that complies with GB/T197 and a tolerance band of 6h, and can withstand the guaranteed load of performance level 8 specified in GB/T3098.2. 4.8 Hydrogen embrittlement resistance
Self-extruding screws, especially those that have been electroplated, tend to fracture due to hydrogen embrittlement. Therefore, the process should be reviewed according to the hydrogen embrittlement test (parallel bearing surface method) specified in GB/T3078.17 to ensure that the process related to hydrogen embrittlement is under control. Once hydrogen embrittlement is found, the process must be improved.
The electroplated screws should be hydrogen-driven according to the provisions of GB/T5267. Note: It is better to apply non-electrolytic zinc powder coating according to the provisions of ISO10683. 4.9 Core hardness after tempering
According to the method described in Article 5.8, the reduction in the core hardness measured after tempering should not exceed 20HV. 4.10 Destructive tensile load
Screws with a length of ≥12mm. or ≥3d can be subjected to tensile test by agreement between the supplier and the buyer. Note: The destructive tensile load given in Table 3 is for reference only. 5 Test method
5.1 Core hardness test
The core hardness shall be measured at the 1/2 radius of the screw cross section. This section shall be away from the end and pass through the thread minor diameter. The test shall be carried out in accordance with the provisions of GB/T4340.1.
5.2 Surface hardness test
During routine testing, the surface hardness can be measured at the end, shank or head of the screw (as long as the depth of the surface carburized layer and the geometric shape of the screw allow), see Figure 1. The test method shall be in accordance with the provisions of GB/T4340.1. The hardness test shall be carried out after the coating is removed. During arbitration testing, for screws with a nominal thread diameter ≥4mm, a Vickers microhardness tester (test force HVo.1) shall be used. The measurement shall be carried out on the tooth profile of the longitudinal section specimen at a distance of at least 0.05mm from the edge of the specimen. For screws with a nominal thread diameter <4mm, the test conditions shall be determined by negotiation.
Figure 1 Measurement location of surface hardness
5.3 Surface carburized layer depth test
Surface carburized layer depth is the distance from the surface to a point perpendicular to the surface, the hardness of which is the actual hardness of the core plus 30HV0.3.
In arbitration test, a microhardness tester should be used with a test force of HVo.3. The preparation of metallographic specimens is shown in Figure 2. 1) Only for incomplete carburization of thread profile. Figure 2 Measurement location of surface carburized layer depth
5.4 Destructive torque test
GB/T 3098.7--2000
Fix the screw specimen firmly into the fixture by appropriate means, see Figure 3. It should be ensured that at least two complete threads are clamped in the fixture, and at least two complete threads are left outside the fixture. In addition, use a calibrated and suitable measuring device to apply torque to the screw until the screw fails. Record the torque value when the screw fails. The value shall comply with the provisions of Table 3.
1-Die
Figure 3 Typical torque test device
5.5 Head firmness test
Insert the screw specimen into the hole of the wedge (or other suitable fixture). Hole diameter: For screws ≤M6, the hole diameter is the nominal thread diameter plus 0.05mm; for screws >M6 to M12, the hole diameter is the nominal thread diameter plus 0.1mm. Apply axial pressure to the screw until the head bearing surface is in contact with the inclined surface (the angle between the head bearing surface and the vertical surface of the screw axis is 7°), see Figure 4. This test is not applicable to countersunk screws.
Note: Usually, a suitable hand hammer is used to hit once or several times to achieve 7 permanent deformation. 1 Wedge: 2 Pressure load
Figure 4 Head firmness test
5.6 Tightening performance test
The tightening performance test can show the ability to extrusion form threads in steel parts. Screw the screw specimen into the test plate (see Figure 5 for dimensions) until at least one thread (except the end of the screw) protrudes from the test plate. When starting to squeeze the thread, use axial force: for screws ≤M5, the maximum axial force Fmax-50N; for screws ≥M5, the maximum axial force Fmm×—100 N.
GB/T3098.7—2000
During the arbitration test, the tightening speed should not exceed 0.5s-1 (30r/min). The maximum torque that occurs during the test is the screw-in torque. Lubricant can be added to achieve the specified screw-in torque. The test plate should be made of low-carbon rolled steel plate with a hardness of 140~~180HV30. The thickness of the test plate should be equal to the nominal diameter of the screw thread, and the hole diameter should be as specified in Table 5.
Nominal thread diameter
Thickness and hole diameter of the test plate
Note: The thickness tolerance of the test plate should comply with the provisions of GB/T709 (rolled steel plate). 5.7 Hydrogen embrittlement resistance test
Hydrogen embrittlement resistance test See GB /T3098.17.
5.8 Re-tempering test
Before and after the re-tempering test (temperature 330℃, insulation for 1h), the difference in the average hardness of the three points of the core of the same screw should not be greater than 20HV. This test is not mandatory and is only applicable to arbitration tests in case of disputes. 5.9 Tensile test
Install the screw specimen on the tensile testing machine, and ensure that at least 6 threads are exposed during installation. Apply axial load to the screw until the screw breaks. During the test, the moving speed of the chuck should not exceed 25m m/min. To prevent the specimen from being subjected to lateral loads, the chuck of the testing machine should be able to automatically center. The fracture should occur at the rod or threaded portion, and should not occur at the junction of the nail head and the rod. 6 Torque wrench
The measurement error of the torque wrench used in the torque test and screw-in performance test should be within ±3% of the specified torque value. A power device that can display torque with equivalent accuracy can also be used. A manual torque wrench should be used for arbitration tests. 7 Marking
Sign symbol
Marking for surface-hardened and tempered self-extruding screws The symbol is "-○-". 7.2 Identification
Surface hardened self-extruding screws shall be marked with concave or convex marks according to the symbols specified in Article 7.1. For hexagonal head screws or hexalobular head screws with a nominal thread diameter ≥ 5mm, the mark must be made and should be made on the nail head as much as possible. With the agreement between the supplier and the buyer, other types of surface hardened and tempered self-extruding screws may also use the above marks. 7.3 Trademark (Identification) Mark
For all products that require the production of marking symbols, it is mandatory to mark the trademark or manufacturer's identification mark. 1497—2000
The screws with no permanent deformation of the thread (checked under a 10x magnifying glass) shall be able to extrude the matching internal threads on the test plate specified in 5.6. During the extrusion of the thread, the screwing torque shall not exceed the screwing torque value specified in Table 3. The internal threads formed by screw extrusion on the test plate shall be able to be screwed into the external thread fasteners with threads in accordance with GB/T197 and a tolerance band of 6h, and can withstand the guaranteed load of performance level 8 specified in GB/T3098.2. 4.8 Hydrogen embrittlement resistance
Self-extruding screws, especially electroplated self-extruding screws, tend to fracture due to hydrogen embrittlement. Therefore, the process shall be reviewed according to the hydrogen embrittlement test (parallel bearing surface method) specified in GB/T3078.17 to ensure that the process related to hydrogen embrittlement is under control. Once hydrogen embrittlement is found, the process must be improved.
The electroplated screws shall be hydrogen driven according to the provisions of GB/T5267. Note: The non-electrolytic zinc powder coating shall be carried out in accordance with the provisions of ISO10683. 4.9 Core hardness after tempering
The core hardness reduction value measured after tempering according to the method described in 5.8 shall not exceed 20HV. 4.10 Destructive tensile load
Screws with a length of ≥12mm. or ≥3d may be subjected to tensile tests upon agreement between the supplier and the buyer. Note: The destructive tensile loads given in Table 3 are for reference only. 5 Test method
5.1 Core hardness test
The core hardness shall be measured at the 1/2 radius of the screw cross section. The section shall be away from the end and pass through the thread minor diameter. The test shall be carried out in accordance with the provisions of GB/T4340.1.
5.2 Surface hardness test
During conventional testing, the surface hardness may be measured at the end, shank or head of the screw (as long as the depth of the surface carburized layer and the geometric shape of the screw allow), see Figure 1. The test method shall be in accordance with the provisions of GB/T4340.1. The hardness test shall be carried out after the coating is removed. For arbitration tests, a Vickers microhardness tester (test force HVo.1) shall be used for screws with a nominal thread diameter ≥4mm. The measurement shall be carried out on the tooth profile of the longitudinal section specimen at a position at least 0.05mm away from the edge of the specimen. For screws with a nominal thread diameter <4mm, the test conditions shall be determined through negotiation.
Figure 1 Measurement position of surface hardness
5.3 Surface carburized layer depth test
The surface carburized layer depth is the distance from the surface to a point perpendicular to the surface, the hardness of which is the actual hardness of the core plus 30HV0.3.
For arbitration tests, a microhardness tester shall be used with a test force of HVo.3. The preparation of the metallographic specimen is shown in Figure 2. 1) Only used for thread profiles that are not completely carburized. Figure 2 Measurement location of surface carburized layer depth
5.4 Destructive torque test
GB/T 3098.7--2000
Fix the screw specimen firmly into the fixture by appropriate means, see Figure 3. It should be ensured that at least two complete threads are clamped in the fixture, and at least two complete threads are left outside the fixture. In addition, use a calibrated and suitable measuring device to apply torque to the screw until the screw is broken. Record the torque value when the screw is broken. The value should comply with the provisions of Table 3.
1-Die
Figure 3 Typical torque test device
5.5 Head firmness test
Insert the screw specimen into the hole of the wedge pad (or other suitable fixture). Hole diameter: For screws ≤M6, the hole diameter is the nominal thread diameter plus 0.05mm; for screws >M6~M12, the hole diameter is the nominal thread diameter plus 0.1mm. Apply axial pressure to the screw until the head bearing surface is in contact with the inclined surface (the angle between the head bearing surface and the vertical surface of the screw axis is 7°), see Figure 4. This test is not applicable to countersunk screws.
Note: Usually, a permanent deformation of 7 is achieved with one or more blows using an appropriate hammer. 1 Wedge: 2 Pressure load
Figure 4 Head firmness test
5.6 Tightening performance test
The tightening performance test can show the ability to squeeze threads in steel parts. Screw the screw specimen into the test plate (dimensions see Figure 5) until at least one thread (except the end of the screw) protrudes from the test plate. When starting to squeeze the thread, the axial force should be used: for screws ≤M5, the maximum axial force Fmax-50N; for screws ≥M5, the maximum axial force Fmm×—100N.
GB/T3098.7—2000
During the arbitration test, the tightening speed should not exceed 0.5s-1 (30r/min). The maximum torque occurring during the test is the screw-in torque". Lubricant can be added to achieve the specified screw-in torque. The test plate should be made of low-carbon rolled steel plate with a hardness of 140~~180HV30. The thickness of the test plate should be equal to the nominal thread diameter of the screw, and the hole diameter should be as specified in Table 5.
Nominal thread diameter
Thickness and hole diameter of the test plate
Note: The thickness tolerance of the test plate should comply with the provisions of GB/T709 (rolled steel plate). 5.7 Hydrogen embrittlement resistance test
See GB for hydrogen embrittlement resistance test /T3098.17.
5.8 Re-tempering test
Before and after the re-tempering test (temperature 330℃, insulation for 1h), the difference in the average hardness of the three points of the core of the same screw should not be greater than 20HV. This test is not mandatory and is only applicable to arbitration tests in case of disputes. 5.9 Tensile test
Install the screw specimen on the tensile testing machine, and ensure that at least 6 threads are exposed during installation. Apply axial load to the screw until the screw breaks. During the test, the moving speed of the chuck should not exceed 25m m/min. To prevent the specimen from being subjected to lateral loads, the chuck of the testing machine should be able to automatically center. The fracture should occur at the rod or threaded portion, and should not occur at the junction of the nail head and the rod. 6 Torque wrench
The measurement error of the torque wrench used in the torque test and screw-in performance test should be within ±3% of the specified torque value. A power device that can display torque with equivalent accuracy can also be used. A manual torque wrench should be used for arbitration tests. 7 Marking
Sign symbol
Marking for surface-hardened and tempered self-extruding screws The symbol is "-○-". 7.2 Identification
Surface hardened self-extruding screws shall be marked with concave or convex marks according to the symbols specified in Article 7.1. For hexagonal head screws or hexalobular head screws with a nominal thread diameter ≥ 5mm, the mark must be made and should be made on the nail head as much as possible. With the agreement between the supplier and the buyer, other types of surface hardened and tempered self-extruding screws may also use the above marks. 7.3 Trademark (Identification) Mark
For all products that require the production of marking symbols, it is mandatory to mark the trademark or manufacturer's identification mark. 1497—2000
The screws with no permanent deformation of the thread (checked under a 10x magnifying glass) shall be able to extrude the matching internal threads on the test plate specified in 5.6. During the extrusion of the thread, the screwing torque shall not exceed the screwing torque value specified in Table 3. The internal threads formed by screw extrusion on the test plate shall be able to be screwed into the external thread fasteners with threads in accordance with GB/T197 and a tolerance band of 6h, and can withstand the guaranteed load of performance level 8 specified in GB/T3098.2. 4.8 Hydrogen embrittlement resistance
Self-extruding screws, especially electroplated self-extruding screws, tend to fracture due to hydrogen embrittlement. Therefore, the process shall be reviewed according to the hydrogen embrittlement test (parallel bearing surface method) specified in GB/T3078.17 to ensure that the process related to hydrogen embrittlement is under control. Once hydrogen embrittlement is found, the process must be improved.
The electroplated screws shall be hydrogen driven according to the provisions of GB/T5267. Note: The non-electrolytic zinc powder coating shall be carried out in accordance with the provisions of ISO10683. 4.9 Core hardness after tempering
The core hardness reduction value measured after tempering according to the method described in 5.8 shall not exceed 20HV. 4.10 Destructive tensile load
Screws with a length of ≥12mm. or ≥3d may be subjected to tensile tests upon agreement between the supplier and the buyer. Note: The destructive tensile loads given in Table 3 are for reference only. 5 Test method
5.1 Core hardness test
The core hardness shall be measured at the 1/2 radius of the screw cross section. The section shall be away from the end and pass through the thread minor diameter. The test shall be carried out in accordance with the provisions of GB/T4340.1.
5.2 Surface hardness test
During conventional testing, the surface hardness may be measured at the end, shank or head of the screw (as long as the depth of the surface carburized layer and the geometric shape of the screw allow), see Figure 1. The test method shall be in accordance with the provisions of GB/T4340.1. The hardness test shall be carried out after the coating is removed. For arbitration tests, a Vickers microhardness tester (test force HVo.1) shall be used for screws with a nominal thread diameter ≥4mm. The measurement shall be carried out on the tooth profile of the longitudinal section specimen at a position at least 0.05mm away from the edge of the specimen. For screws with a nominal thread diameter <4mm, the test conditions shall be determined through negotiation.
Figure 1 Measurement position of surface hardness
5.3 Surface carburized layer depth test
The surface carburized layer depth is the distance from the surface to a point perpendicular to the surface, the hardness of which is the actual hardness of the core plus 30HV0.3.
For arbitration tests, a microhardness tester shall be used with a test force of HVo.3. The preparation of the metallographic specimen is shown in Figure 2. 1) Only used for thread profiles that are not completely carburized. Figure 2 Measurement location of surface carburized layer depth
5.4 Destructive torque test
GB/T 3098.7--2000
Fix the screw specimen firmly into the fixture by appropriate means, see Figure 3. It should be ensured that at least two complete threads are clamped in the fixture, and at least two complete threads are left outside the fixture. In addition, use a calibrated and suitable measuring device to apply torque to the screw until the screw is broken. Record the torque value when the screw is broken. The value should comply with the provisions of Table 3.
1-Die
Figure 3 Typical torque test device
5.5 Head firmness test
Insert the screw specimen into the hole of the wedge pad (or other suitable fixture). Hole diameter: For screws ≤M6, the hole diameter is the nominal thread diameter plus 0.05mm; for screws >M6~M12, the hole diameter is the nominal thread diameter plus 0.1mm. Apply axial pressure to the screw until the head bearing surface is in contact with the inclined surface (the angle between the head bearing surface and the vertical surface of the screw axis is 7°), see Figure 4. This test is not applicable to countersunk screws.
Note: Usually, a permanent deformation of 7 is achieved with one or more blows using an appropriate hammer. 1 Wedge: 2 Pressure load
Figure 4 Head firmness test
5.6 Tightening performance test
The tightening performance test can show the ability to squeeze threads in steel parts. Screw the screw specimen into the test plate (dimensions see Figure 5) until at least one thread (except the end of the screw) protrudes from the test plate. When starting to squeeze the thread, the axial force should be used: for screws ≤M5, the maximum axial force Fmax-50N; for screws ≥M5, the maximum axial force Fmm×—100N.
GB/T3098.7—2000
During the arbitration test, the tightening speed should not exceed 0.5s-1 (30r/min). The maximum torque occurring during the test is the screw-in torque". Lubricant can be added to achieve the specified screw-in torque. The test plate should be made of low-carbon rolled steel plate with a hardness of 140~~180HV30. The thickness of the test plate should be equal to the nominal thread diameter of the screw, and the hole diameter should be as specified in Table 5.
Nominal thread diameter
Thickness and hole diameter of the test plate
Note: The thickness tolerance of the test plate should comply with the provisions of GB/T709 (rolled steel plate). 5.7 Hydrogen embrittlement resistance test
See GB for hydrogen embrittlement resistance test /T3098.17.
5.8 Re-tempering test
Before and after the re-tempering test (temperature 330℃, insulation for 1h), the difference in the average hardness of the three points of the core of the same screw should not be greater than 20HV. This test is not mandatory and is only applicable to arbitration tests in case of disputes. 5.9 Tensile test
Install the screw specimen on the tensile testing machine, and ensure that at least 6 threads are exposed during installation. Apply axial load to the screw until the screw breaks. During the test, the moving speed of the chuck should not exceed 25m m/min. To prevent the specimen from being subjected to lateral loads, the chuck of the testing machine should be able to automatically center. The fracture should occur at the rod or threaded portion, and should not occur at the junction of the nail head and the rod. 6 Torque wrench
The measurement error of the torque wrench used in the torque test and screw-in performance test should be within ±3% of the specified torque value. A power device that can display torque with equivalent accuracy can also be used. A manual torque wrench should be used for arbitration tests. 7 Marking
Sign symbol
Marking for surface-hardened and tempered self-extruding screws The symbol is "-○-". 7.2 Identification
Surface hardened self-extruding screws shall be marked with concave or convex marks according to the symbols specified in Article 7.1. For hexagonal head screws or hexalobular head screws with a nominal thread diameter ≥ 5mm, the mark must be made and should be made on the nail head as much as possible. With the agreement between the supplier and the buyer, other types of surface hardened and tempered self-extruding screws may also use the above marks. 7.3 Trademark (Identification) Mark
For all products that require the production of marking symbols, it is mandatory to mark the trademark or manufacturer's identification mark. 1493 Surface carburized layer depth test
Surface carburized layer depth is the distance from the surface to a point perpendicular to the surface, the hardness of which is the actual hardness of the core plus 30HV0.3.
In arbitration test, a microhardness tester should be used with a test force of HVo.3. The preparation of metallographic specimens is shown in Figure 2. 1) Only for thread profiles that are not completely carburized. Figure 2 Measurement position of surface carburized layer depth
5.4 Destructive torque test
GB/T 3098.7--2000
Fix the screw specimen firmly into the fixture by appropriate means, see Figure 3. It should be ensured that at least two complete threads are clamped in the fixture, and at least two complete threads are left outside the fixture. In addition, use a calibrated and suitable measuring device to apply torque to the screw until the screw fails. Record the torque value when the screw fails. This value should comply with the provisions of Table 3.
1-Die
Figure 3 Typical torque test device
5.5 Head firmness test
Insert the screw specimen into the hole of the wedge (or other suitable fixture). Hole diameter: For screws ≤M6, the hole diameter is the nominal thread diameter plus 0.05mm; for screws >M6 to M12, the hole diameter is the nominal thread diameter plus 0.1mm. Apply axial pressure to the screw until the head bearing surface is in contact with the inclined surface (the angle between the head bearing surface and the vertical surface of the screw axis is 7°), see Figure 4. This test is not suitable for countersunk screws.
Note: Usually, a permanent deformation of 7 is achieved with one or more blows using an appropriate hand hammer. 1 Wedge: 2 Pressure load
Figure 4 Head firmness test
5.6 Tightening performance test
The tightening performance test can show the ability to extrude threads in steel parts. Screw the screw specimen into the test plate (see Figure 5 for dimensions) until at least one thread (except the end of the screw) protrudes from the test plate. When starting to squeeze the thread, use axial force: for screws ≤M5, the maximum axial force Fmax-50N; for screws ≥M5, the maximum axial force Fmm×—100 N.
GB/T3098.7—2000
During the arbitration test, the tightening speed should not exceed 0.5s-1 (30r/min). The maximum torque that occurs during the test is the screw-in torque. Lubricant can be added to achieve the specified screw-in torque. The test plate should be made of low-carbon rolled steel plate with a hardness of 140~~180HV30. The thickness of the test plate should be equal to the nominal diameter of the screw thread, and the hole diameter should be as specified in Table 5.
Nominal thread diameter
Thickness and hole diameter of the test plate
Note: The thickness tolerance of the test plate should comply with the provisions of GB/T709 (rolled steel plate). 5.7 Hydrogen embrittlement resistance test
Hydrogen embrittlement resistance test See GB /T3098.17.
5.8 Re-tempering test
Before and after the re-tempering test (temperature 330℃, insulation for 1h), the difference in the average hardness of the three points of the core of the same screw should not be greater than 20HV. This test is not mandatory and is only applicable to arbitration tests in case of disputes. 5.9 Tensile test
Install the screw specimen on the tensile testing machine, and ensure that at least 6 threads are exposed during installation. Apply axial load to the screw until the screw breaks. During the test, the moving speed of the chuck should not exceed 25m m/min. To prevent the specimen from being subjected to lateral loads, the chuck of the testing machine should be able to automatically center. The fracture should occur at the rod or threaded portion, and should not occur at the junction of the nail head and the rod. 6 Torque wrench
The measurement error of the torque wrench used in the torque test and screw-in performance test should be within ±3% of the specified torque value. A power device that can display torque with equivalent accuracy can also be used. A manual torque wrench should be used for arbitration tests. 7 Marking
Sign symbol
Marking for surface-hardened and tempered self-extruding screws The symbol is "-○-". 7.2 Identification
Surface hardened self-extruding screws shall be marked with concave or convex marks according to the symbols specified in Article 7.1. For hexagonal head screws or hexalobular head screws with a nominal thread diameter ≥ 5mm, the mark must be made and should be made on the nail head as much as possible. With the agreement between the supplier and the buyer, other types of surface hardened and tempered self-extruding screws may also use the above marks. 7.3 Trademark (Identification) Mark
For all products that require the production of marking symbols, it is mandatory to mark the trademark or manufacturer's identification mark. 1493 Surface carburized layer depth test
Surface carburized layer depth is the distance from the surface to a point perpendicular to the surface, the hardness of which is the actual hardness of the core plus 30HV0.3.
In arbitration test, a microhardness tester should be used with a test force of HVo.3. The preparation of metallographic specimens is shown in Figure 2. 1) Only for thread profiles that are not completely carburized. Figure 2 Measurement position of surface carburized layer depth
5.4 Destructive torque test
GB/T 3098.7--2000
Fix the screw specimen firmly into the fixture by appropriate means, see Figure 3. It should be ensured that at least two complete threads are clamped in the fixture, and at least two complete threads are left outside the fixture. In addition, use a calibrated and suitable measuring device to apply torque to the screw until the screw fails. Record the torque value when the screw fails. This value should comply with the provisions of Table 3.
1-Die
Figure 3 Typical torque test device
5.5 Head firmness test
Insert the screw specimen into the hole of the wedge (or other suitable fixture). Hole diameter: For screws ≤M6, the hole diameter is the nominal thread diameter plus 0.05mm; for screws >M6 to M12, the hole diameter is the nominal thread diameter plus 0.1mm. Apply axial pressure to the screw until the head bearing surface is in contact with the inclined surface (the angle between the head bearing surface and the vertical surface of the screw axis is 7°), see Figure 4. This test is not suitable for countersunk screws.
Note: Usually, a permanent deformation of 7 is achieved with one or more blows using an appropriate hand hammer. 1 Wedge: 2 Pressure load
Figure 4 Head firmness test
5.6 Tightening performance test
The tightening performance test can show the ability to extrude threads in steel parts. Screw the screw specimen into the test plate (see Figure 5 for dimensions) until at least one thread (except the end of the screw) protrudes from the test plate. When starting to squeeze the thread, use axial force: for screws ≤M5, the maximum axial force Fmax-50N; for screws ≥M5, the maximum axial force Fmm×—100 N.
GB/T3098.7—2000
During the arbitration test, the tightening speed should not exceed 0.5s-1 (30r/min). The maximum torque that occurs during the test is the screw-in torque. Lubricant can be added to achieve the specified screw-in torque. The test plate should be made of low-carbon rolled steel plate with a hardness of 140~~180HV30. The thickness of the test plate should be equal to the nominal diameter of the screw thread, and the hole diameter should be as specified in Table 5.
Nominal thread diameter
Thickness and hole diameter of the test plate
Note: The thickness tolerance of the test plate should comply with the provisions of GB/T709 (rolled steel plate). 5.7 Hydrogen embrittlement resistance test
Hydrogen embrittlement resistance test See GB /T3098.17.
5.8 Re-tempering test
Before and after the re-tempering test (temperature 330℃, insulation for 1h), the difference in the average hardness of the three points of the core of the same screw should not be greater than 20HV. This test is not mandatory and is only applicable to arbitration tests in case of disputes. 5.9 Tensile test
Install the screw specimen on the tensile testing machine, and ensure that at least 6 threads are exposed during installation. Apply axial load to the screw until the screw breaks. During the test, the moving speed of the chuck should not exceed 25m m/min. To prevent the specimen from being subjected to lateral loads, the chuck of the testing machine should be able to automatically center. The fracture should occur at the rod or threaded portion, and should not occur at the junction of the nail head and the rod. 6 Torque wrench
The measurement error of the torque wrench used in the torque test and screw-in performance test should be within ±3% of the specified torque value. A power device that can display torque with equivalent accuracy can also be used. A manual torque wrench should be used for arbitration tests. 7 Marking
Sign symbol
Marking for surface-hardened and tempered self-extruding screws The symbol is "-○-". 7.2 Identification
Surface hardened self-extruding screws shall be marked with concave or convex marks according to the symbols specified in Article 7.1. For hexagonal head screws or hexalobular head screws with a nominal thread diameter ≥ 5mm, the mark must be made and should be made on the nail head as much as possible. With the agreement between the supplier and the buyer, other types of surface hardened and tempered self-extruding screws may also use the above marks. 7.3 Trademark (Identification) Mark
For all products that require the production of marking symbols, it is mandatory to mark the trademark or manufacturer's identification mark. 149
Tip: This standard content only shows part of the intercepted content of the complete standard. If you need the complete standard, please go to the top to download the complete standard document for free.