The issue of matching fastener performance grades
Thread Content
Nuts are suitable for performance grades 6, 8, and 10, while bolts are suitable for performance grades 5.6, 8.8, 9.8, and 10.9. According to the grade matching regulations, the grade of the bolt must be higher than that of the nut. Which grade of nut matches a 5.6 grade bolt?
For low-strength bolt-nut combinations, there is no need to follow the requirement that the nut grade should be lower; according to the standards, a 5.6 bolt can be paired with a 6 nut
Grade 5.6 bolts are intended for use in areas that are not under pressure; such bolts generally have a large strength margin. Unlike those used in pressure-bearing areas, where no defects in the bolts are allowed to ensure safety, this is not the case here.
What is the grade threshold for low intensity? Where is it described?
How can one determine whether a certain grade can be used in pressure-bearing applications?
Please refer to HG/T20613, 20634
Fasteners for flanges are specified in HG/T20613 and 20634
Last year, there were no items with a score below 8.8 on the elimination list!
Bolts of grade 5.6 should be matched with nuts of grade 5. The nut size standard can be GB/T41-2000, Class C nuts. Grade 5.6 is a low-strength grade of bolt, so nuts of a lower grade should also be used to match it. The nut size standard is not the one specified in the GB/T6170 standard posted by the original poster.
Thank you, I saw it. However, the table only indicates which strength corresponds to each grade, without showing how to distinguish between them