This standard specifies the mechanical properties of nuts with specified guaranteed load values when the test is carried out at an ambient temperature of 10 to 35 °C. Products judged to comply with this standard under this ambient temperature condition may have different mechanical and physical properties at higher or lower temperatures, and users should pay attention. Nuts applicable to this standard: Nominal thread diameter D≤39 mm; Ordinary thread conforming to GB/T 192; Coarse thread diameter and pitch combination conforming to GB/T 193; Basic dimensions conforming to GB/T 196; Tolerances and fits specified in GB/T 197; specific mechanical requirements, width across flats in accordance with GB/T 3104 or equivalent; nominal height ≥ 0.5D; made of carbon steel or alloy steel. This standard does not apply to nuts with special performance requirements, such as: locking performance (GB/T 3098.9); weldability; corrosion resistance (GB/T 3098.15); working temperature higher than +300°C or lower than -50°C performance requirements.