The nut is a unified whole. The nut is one of the accessories, including: bolts, screws, and nuts. As long as there are threaded fasteners, bolts are a type of fastener composed of two parts: the head and the screw. Used to securely connect two parts with through holes. The nut has an internal threaded hole, and its shape is generally flat hexagonal column, and also flat square column or flat cylindrical. It is used to fasten and connect two parts with bolts, studs or machine screws, making it a piece as a whole.
The types of nuts are: hexagonal nuts, thin nuts, thickened nuts, slotted nuts, square nuts, cap nuts, anti-theft nuts, flange nuts, wing nuts, ring nuts, round nuts, welded nuts, T-shaped nuts, Four claw nuts, K caps, self-locking nuts, lock nuts, tapered nuts, stainless steel nuts, inner and outer thread nuts, nylon nuts, disc nuts, spring nuts, fine thread nuts, counter thread nuts, hub nuts, high strength nuts , cage nuts, reed nuts, pipe nuts, embedded nuts, torque nuts, other nuts, lock nuts, rivet nuts, copper nuts, nuts, plastic nuts, inch nuts, mobile phone nuts, embedded nuts, plastic wings nuts etc.       (1) Carbon steel We distinguish low carbon steel, medium carbon steel, high carbon steel and alloy steel by the carbon content in carbon steel materials.
       1. Low carbon steel C%≤0.25% is usually called A3 steel in China. Foreign countries are basically called 1008, 1015, 1018, 1022 and so on. Mainly used for grade 4.8 bolts and grade 4 nuts, small screws and other products without hardness requirements. (Note: Drilling screws are mainly made of 1022 material.)
       2. Medium carbon steel 0.25%.
       3. High carbon steel C%>0.45%. It is basically not used in the market at present.
       4. Alloy steel: Add alloy elements to ordinary carbon steel to increase some special properties of steel: such as 35, 40 chromium molybdenum, SCM435, 10B38.
       (2) Stainless steel performance grades: 45, 50, 60, 70, 80.
       Mainly divided into austenite (18%Cr, 8%Ni) has good heat resistance, good corrosion resistance and good weldability. A1,A2,A4. Martensite and 13%Cr have poor corrosion resistance, high strength and good wear resistance. C1, C2, C4 ferritic stainless steel. 18%Cr has better upsetting forgeability and stronger corrosion resistance than martensite. At present, imported materials on the market are mainly Japanese products. According to the level, it is mainly divided into SUS302, SUS304 and SUS316.
       (3) Commonly used materials for copper are brass and zinc-copper alloy. H62, H65 and H68 copper are mainly used as standard parts in the market.