Differences between nuts
Thread Content
Today at the site, I accidentally saw that both nuts had the marking M8 on them. I did a search on Baidu, but found all sorts of information; it’s better to ask a professional for an answer.
The main differences between the primary nut and the secondary nut are as follows: First, the materials are different. The main nut is generally made of materials such as carbon steel, stainless steel, and duplex stainless steel ； The secondary nuts are usually made of materials such as aluminum alloy and brass. II. The strength is different. The strength requirements for the main nut are higher than those for the secondary nut; generally, the tensile strength of the main nut can reach 1160–1320 N/mm2, while that of the secondary nut is 600–830 N/mm2. III. The structures are different. The main nut is commonly used to connect components, and it bears tensile forces ； The counternut is used to hold two parts together, as it bears the tightening force. IV. Different uses. The main nut is used for connection, such as with threaded fasteners like bolts and screws ； The secondary nut is used for locking, such as in a nut and washer assembly. -
Thank you for the prompt reply; both of these are main nuts, and some people say it’s the pitch
Yes, M8 refers to the pitch. M8 indicates that the pitch of the thread is 8 mm; such nuts can be used on threaded components of various diameters. -
8M is the strength grade of the nut; the nuts on the left and right are identical. (Not M8)
The strength grade symbol for American standard nuts. For more details, you can refer to the ASME standards.
It’s not M8, it’s 8M. ASTM A194 grade 8M corresponds to 316, while ASTM A194 grade 8 corresponds to 304. The mechanical properties and chemical composition can be found in the standard ASTM A194.
Material grade S31600