This standard specifies the materials, test methods and markings for equal-length studs, studs, hexagonal bolts, hexagonal flange bolts, hexagonal nuts, cover nuts and load-bearing sleeves. This standard is applicable to fasteners used under working conditions that can withstand high temperatures, alternating loads, and maintain preload and fatigue resistance to a considerable extent. GB/T 3098.8-1992 Mechanical properties of fasteners Heat-resistant threaded connections GB/T3098.8-1992 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Mechanical properties of fasteners
Heat-resistant threaded connection pairs
Mechanical properties of fasteners--Components for bolted connections made mainly from materialswith a high temperature strengthSubject content and scope of application
GB/T 3098.8—92
This standard specifies the materials, test methods and markings for equal-length studs, studs, hexagonal head bolts, hexagonal flange bolts, hexagonal nuts, cover nuts and load-bearing sleeves.
This standard is applicable to fasteners used under working conditions that can withstand high temperatures and alternating loads and maintain preload and fatigue resistance to a considerable extent.
2 Reference standards
GB699 Steel grades and general technical conditions for high-quality carbon structural steel Technical conditions for alloy structural steel
GB3077
GBn 177
GB 1979
High-temperature alloy hot-rolled and forged bars for ordinary load-bearing parts Structural steel macrostructure defect rating chart
Mechanical properties of fasteners Bolts, screws and studs GB 3098.1
GB 3098. 2
GB 3098. 6
Mechanical properties of fasteners Nuts
Mechanical properties of fasteners Macrostructure and defects of stainless steel bolts, screws, studs and nuts Acid etching test method Technical conditions for recommended steel grades of YB/Z8 heat-resistant steel
3 Materials
3.1 For materials above +300℃, see the table. Extreme temperature for continuous working (reference) Material grade 30CrMo 35CrMo 35CrMo A State Technical Supervision Bureau approved on November 5, 1992 150 Bolts and studs Standard number GB3077 Material grade 35, 45 20CrMoA Standard number GB 3077
1993-06-01 implementationwww.bzxz.net
Ultimate temperature for continuous working (reference)
Material grade
21CrMoV
20CrMoV
21CrMoV
GB/T3098.8-92
Bolts, studs
Standard number
20CrMoVTiB
20CrMoVNbTiB
2Cr12WMoVNbB
GH2132
(YB/Z8)
G Bn177
Note:) Bolts and studs should have a higher hardness than nuts (e.g. 30-50HB higher). ② Material of the load-bearing sleeve. It is recommended to use the same material as the stud. Material grade
20CrMoA
35CrMoA
30CrMo
35CrMa
20CrMoV
21CrMov
20CrMov
21CrMoV
Standard number
GB3077
GB3077
3.2 The material should be inspected by low-power organization. Among them, general looseness, central looseness and square-shaped segregation shall not exceed the second level specified in GB1979.
4 Test methods
4.1 For fasteners that are machined but not heat treated, it is only necessary to inspect their materials in accordance with the relevant material standards or agreements. 4.2 Fasteners that have been cold or hot formed should be inspected after heat treatment. 4.3 For the test methods of externally threaded fasteners, the agreement can be made in accordance with the provisions of GB3098.1. 4.4 For the test methods of internally threaded fasteners, the agreement can be made in accordance with the provisions of GB3098.2. 4.5 For the test methods of stainless steel fasteners, the agreement can be made in accordance with the provisions of GB3098.6. 4.6 Macrostructural defects shall be inspected in accordance with the provisions of GB226, and spot checks may be carried out according to the furnace number. 4.7 Bolts and studs may be subject to 100% magnetic flaw detection or (and) ultrasonic flaw detection as stipulated in the agreement. 5 Marking
5.1 For fastener products that refer to this standard, the material marking (material grade) and the manufacturer's trademark or identification symbol must be made at the agreed position (generally exposed, non-important surfaces, such as: the top surface of the bolt head; the end face of the stud screwed into the nut; the hexagonal surface of the nut). 5.2 It is not allowed to use electrolytic corrosion method to make markings. 151
Additional instructions:
GB/T3098.892
This standard was proposed by the Ministry of Machinery and Electronics Industry of the People's Republic of China and is under the jurisdiction of the National Technical Committee for Fastener Standardization. This standard was drafted by the Mechanical Standardization Research Institute of the Ministry of Machinery and Electronics Industry. This standard refers to DIN267 Part 13-1980 "Technical Conditions for Low-Temperature or Heat-Resistant Fasteners". 152
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