Materials for internal threads such as nuts：
No mechanical properties or ISO Class 5-6 SAE Grade 3-4 generally use C1010 Q235A or C15, do not need heat treatment, cold processing can be. ISO Class 8, SAE Grade 5, generally use Ml35 SAE1035 DIN C35, small specifications of nuts do not need hot place to reach the required mechanical properties, large specifications to go through heat treatment (quenching + tempering), this GB3098.2 said very clear.
ISO Class 10, SAE Grade 8 generally use medium carbon steel after heat treatment can reach its strength requirements. Such as SAE1035 medium carbon steel. It is important to note that, different from bolts, the force of nuts is mainly compressed rather than extended. Therefore, the strength of nuts is not only related to the material, but also to many factors, including accuracy, pitch, chamfering inside the nut, and nut thickness.
