Bolt and nut grades
Thread Content
Generally, is the grade of the bolt one higher or one lower than that of the nut? I have checked the previous material lists; the material quality of the bolts should be higher than that of the nuts. For example, bolts made of 35CrMoA are used with nuts made of 30CrMoA. However, I have also read the discussions on the pre-tensioning force of bolts and nuts in the standards related to pressure vessels. Compared to nut loosening or failure, bolt failure is easier to detect. Therefore, when making choices, it is advisable to opt for scenarios where bolt failure occurs, so that problems can be identified promptly. Doesn’t this create a contradiction? Please ask someone who is aware to give an introduction.
The bolt is one grade higher than the nut. The simplest reason is that replacing nuts is easier than replacing bolts.
The reply above is incorrect: “The bolt is one grade higher than the nut.” The simplest reason is that replacing nuts is easier than replacing bolts. ” Bolts are stronger than nuts, but replacing nuts is not more convenient than replacing bolts. It is because bolts are more expensive than nuts, and to prevent the bolts from wearing out due to frequent disassembly, the hardness of bolts is higher than that of nuts.
What was said upstairs is correct; it’s mainly a matter of price, especially for single-shoulder double-head studs – it’s better to buy more nuts
A situation where the strength of the nut is greater than that of the bolt has not been encountered to date.
I’ve learned a lot; I had never thought about these issues on-site before!
The bolt is one grade higher in hardness than the nut; the nut’s hardness is HB20 less than that of the bolt. This ensures that the bolt is more durable than the nut, as bolts are more expensive
One should consider the issue of achieving the service life simultaneously. Generally, the design life of all components in a complete set of equipment should be the same, as this is the most economical and reasonable approach. Bolts and nuts are similar.
Bolts are stronger than nuts, but replacing nuts is not more convenient than replacing bolts. It is because bolts are more expensive than nuts, and to prevent the bolts from wearing out due to frequent disassembly, the hardness of bolts is higher than that of nuts.
Bolts have higher strength than nuts because they are more expensive. To prevent the bolts from wearing out due to frequent disassembly, their hardness is higher than that of nuts.
Agree with the opinion from the 3rd floor; it’s mainly a matter of price