Nut material issue
Thread Content
When using nuts in accordance with GB/T6170-2000, only the grade of the material can be specified; can the material grade be indicated as well? For example: when using double-headed studs in accordance with JB/T4707-2000 and the material grade is 35, should the corresponding nut be designated as grade 20 or grade 8? Thank you for the help!
Writing grade 8 is sufficient; looking at the material list, the lowest grade of material used to manufacture grade 8 nuts is 20
20 is the material, and 8 is the performance grade. Either one will do; as long as the material meets the requirements, any performance grade is acceptable. Once the performance level is determined, the material is essentially fixed as well.
Write level 8; if required, the material of the nut can also be specified
Commercial-grade fasteners only specify the performance grade, not the material grade. For specialty-grade fasteners, the material grade must be specified, and care must be taken to match studs with nuts.
Writing only about material 20 is likely not sufficient; the strength of 20 steel in its as-delivered state is lower than that of nuts of grade 8. Unless no requirements are set for the strength of the nuts, nuts of a lower grade delivered in this condition are still considered acceptable.