GB/T 3098.17-2000 Mechanical properties inspection of fasteners - Hydrogen embrittlement - Preload test - Parallel bearing surface method
Some standard content:
GB/T 3098. 17--2000
Preload test for checking hydrogen embrittlement
This standard is equivalent to the international standard ISO15330:1999 "Parallel bearing surface method for fasteners"
The general title of GB/T3098 is "Mechanical properties of fasteners", which includes the following parts:-GB/T 3098.1-—2000
GB/T 3098. 2--2000
GB/T 3098.3-—2000
GB/T 3098. 4-
GB/T 3098. 5-
-GB/T 3098. 6—2000
GB/T 3098.7—2000
GB/T 3098.8—1992
GB/T 3098.9-
-GB/T 3098.10--1993
GB/T 3098.11—1995
GB/T 3098.12-1996
Mechanical properties of fasteners
Mechanical properties of fasteners
Mechanical properties of fasteners
Mechanical properties of fasteners
Mechanical properties of fasteners
Mechanical properties of fastenersbzxz.net
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 3098:13—1996
-GB/T 3098.14--2000
-GB/T 3098.15—2000
-GB/T 3098.16—2000
GB/T 3098.17—2000
Bolts, screws and studs
Nuts coarse thread
Set screws
Nuts fine thread
Self-sealing screws
Stainless steel bolts, screws and studs
Self-extruding screws
Heat-resistant threaded connections
Effective torque steel hexagonal locking nuts
Bolts, screws, studs and nuts made of non-ferrous metals Self-drilling and tapping screws
Nut cone proof load test
Mechanical properties of fasteners
1~10 mm
Mechanical properties of fasteners
Mechanical properties of fasteners
Mechanical properties of fasteners
Torque test and breaking torque of bolts and screwsNominal diameterNut expansion test
Stainless steel nuts
Stainless steel set screws
Mechanical properties of fasteners
Preload test for hydrogen embrittlementParallel bearing surface methodThis standard is proposed by the State Bureau of Machinery Industry. This standard is under the jurisdiction of the National Technical Committee for Standardization of Fasteners. This standard is under the responsibility of the Mechanical Science Research Institute, and the China Aerospace Standardization Institute, Shanghai Fasteners and Welding Materials Technology Research Institute and Wuhan Automobile Standard Parts Research Institute participated in the drafting. This standard is interpreted by the Secretariat of the National Technical Committee for Standardization of Fasteners. 212
GB/T3098.17—2000
ISOForeword
ISO (International Organization for Standardization) is a worldwide joint organization of national standard bodies (ISO member bodies) of various countries. The formulation of international standards is usually carried out through ISO technical committees. Each member body may participate in a technical committee if it has an interest in a subject being worked on by that committee. International organizations, governmental and non-governmental, associated with ISO, may also take part in the work. ISO has close links with the International Electrotechnical Commission (IEC) for the promotion of electrotechnical standards. International Standards are prepared in accordance with the rules given in the ISO/IEC Guides, Part 3. Draft International Standards adopted by the technical committees are circulated to all member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
International Standard ISO 15330 was prepared by ISO/TC2 Technical Committee SC1, Mechanical Properties of Fasteners, Subcommittee SC1. ISO Introduction
When hydrogen atoms enter the steel matrix, under stress (which may be below the yield strength of the material or even within the normal design strength), they cause a reduction in toughness or load-bearing capacity, fracture (usually submicroscopic fracture) or sudden brittle failure. In alloys that exhibit this phenomenon, conventional tensile tests do not show any reduction in toughness. This phenomenon is often referred to as delayed brittle failure caused by hydrogen, hydrogen stress fracture, or hydrogen embrittlement. Hydrogen can be generated during heat treatment, gas carburizing, cleaning, pickling, phosphating, electroplating, and cathodic protection (corrosion) measures taken in the working environment. Hydrogen can also be generated during production processes such as roll forming, machining, and interrupted drilling that requires coolant or lubricant, as well as during welding or brazing. 213
1 Scope
National Standard of the People's Republic of China
Mechanical properties of fasteners
Preloading test for the detection of hydrogen embrittlement--Parallel bearing surface method This standard specifies the preloading test method for detecting hydrogen embrittlement of fasteners at room temperature. This standard applies to:
a) bolts, screws and studs;
b) self-extruding screws;
c) self-tapping screws;
d) self-drilling and self-tapping screws;
e) nuts,
f) washers.
These fasteners are made of steel and are subjected to tensile stress. The temperature range of this test is 10~35℃.
GB/T3098.17—2000
idtIS15330:1999
This test is only applicable to process control and can be carried out after any manufacturing process, but it is not an acceptance test item. This test can evaluate the differences and changes in process status and technical status, and determine the different effects of different processes, including pre-plating treatment and post-plating treatment (baking) for reducing free hydrogen in fasteners. Manufacturing personnel and process personnel cannot be relieved of the responsibility of adopting and monitoring process control because of this test. Note: If the test is carried out after the final manufacturing process and for more than 24 hours, the probability of detecting hydrogen cells will be significantly reduced. Therefore, under normal circumstances, this test is not suitable for acceptance testing.
Special attention should be paid to the reference comparative test given in Article 7.3. 2 Cited 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/T5277--1985 Fasteners Bolts and screws Through holes (e9vISO273:1979) Self-tapping screws (idtISO2702:1992) GB/T 3098.5--2000
Mechanical properties of fasteners
GB/T3098.7—2000 Mechanical properties of fasteners Self-drilling screws (idtISO7085:1999) GB/T3098.11—1995 Mechanical properties of fasteners Self-drilling and self-tapping screws 3 Terms and definitions
This standard uses the following terms and definitions. Approved by the State Administration of Quality and Technical Supervision on September 26, 2000214
Implementation on February 1, 2001
3.1 Hydrogen embrittlement sensitivity
GB/T 3098. 17--2000
Due to the presence of free hydrogen in steel fasteners, when subjected to corresponding levels of tensile stress and (or) in unfavorable service conditions, steel fasteners exhibit a brittle failure characteristic.
"If the hydrogen embrittlement sensitivity increases, it means that the content of free hydrogen that can cause brittle failure also increases significantly. After the manufacturing process, even after heat treatment (baking) after plating, the sensitivity to hydrogen embrittlement will not be reduced, or it will become insensitive. 3.2 Hydrogen embrittlement tendency
If the fastener is made of steel sensitive to hydrogen embrittlement and has absorbed hydrogen, its failure tendency will increase. Note: If the hydrogen provided in the corresponding process reaches the minimum level and (or) appropriate heat treatment (baking) is carried out after plating to release hydrogen from the steel and no longer avoid hydrogen being absorbed into the steel, the tendency of hydrogen embrittlement will be reduced. 3.3 Production batch
The number of fasteners of the same marking (including product grade, performance level and specification), made from bars, wires, wire or plates from the same furnace, using the same or similar processes and undergoing the same heat treatment and/or coating process throughout the continuous cycle. Interlaced heat treatment or coating process: For continuous production, it means the same treatment cycle without any changes; for non-continuous production, it means the same treatment cycle for the same, adjacent manufacturing batches. Note: From a technical point of view, a production batch can be divided into several manufacturing batches and then merged into the same production batch. 3.4 Manufacturing batch
The number of fasteners belonging to the same production batch manufactured together at the same time. 4 Method
The preload test should be carried out on an appropriate test fixture. The stress on the fastener should be within its yield point or within the range of failure torque. The torque can be applied either by matching nuts (or bolts) or by turning the threaded steel plate, see Figure 1 Figure 3. Other loading methods and fixtures that can ensure that the required stress of the corresponding fastener is within its yield point or within the range of the breaking torque are also allowed. The stress or torque should be maintained for at least 48 hours. The fastener should be tightened to the initial stress or torque every 24 hours, and the fastener should be checked for damage due to hydrogen embrittlement.
5 Test fixtures
Different test fixtures should be used according to the different types of fasteners. 5.1 Bolts, screws and studs
For bolts, screws and studs, a fixture with two parallel hardened steel plates and one or more holes perpendicular to the plate surface should be used, see Figure 1.
The test fixture for bolts, screws and studs consists of an upper plate and a lower plate, see Figure 1. The minimum hardness of the upper and lower plates should be 45HRC. The bearing surface should be ground and its roughness Ra value should not exceed 8μm. The thickness of each steel plate should be ≥1d (d--nominal diameter of the thread). The through hole diameter dh shall comply with the provisions of GB/T5277 for precision assembly and shall not be rounded. The distance (L) between each through hole shall be ≥3d. During the test, it shall be ensured that at least 1d of unthreaded threads are under stress, and no more than 5 threads of complete threads shall extend out of the nut. To meet these requirements, one or more steel plates with parallel planes and surface grinding may be used as pads. The pads may be made of other steels and may have a different hardness from the upper and lower pressure plates. Tighten the matching nuts and perform preload tests on bolts, screws and studs. For studs or screws, nuts shall be used on both sides of the pressure plate. When the pitch of the two ends of the stud is different, the nut at the fine thread end shall be regarded as the "head". Tighten the nut used as the "head" to the end of the thread by hand.
For short screws with L<2.5d, only one steel plate with prefabricated threaded holes is used. The screws can be screwed directly into the steel plate without the use of nuts, but tightened with the screw head. The performance of the steel plate should be the same as that of the upper pressure plate. 215
GB/T3098.17--2000
1-Upper pressure plate; 2-Pad (for long bolts, screws or studs): 3~-Lower pressure plate: 4-Nut for "head" 1) Through hole assembled according to GB/T5277
Figure 1 Test fixture for bolts, screws and studs For bolts and screws without flat bearing surfaces (such as countersunk screws and eye screws), appropriate upper pressure plates or washers should be placed under their heads, see Figure 2.
1 Upper plate with countersunk hole; 2-lower plate
Figure 2 Test fixture for bolts and screws without flat bearing surface 5.2 Self-extruding screws, self-tapping screws and self-drilling self-tapping screws The test fixture for self-extruding screws, self-tapping screws and self-drilling self-tapping screws is a steel plate. The mechanical properties of the steel plate shall comply with the relevant provisions of GB/T3098.7, GB/T3098.5 or GB/T3098.11 for screw-in test, but the threaded holes shall be prefabricated, see Figure 3. 216
d
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.