Currently, the main standard fasteners on the market are made of carbon steel (including free-cutting steel), stainless steel (including free-cutting stainless steel), and copper (including free-cutting copper).
Carbon Steel. We distinguish between low-carbon steel, medium-carbon steel, high-carbon steel, and alloy steel based on the carbon content in the carbon steel material.
1. Low-carbon steel C%≤0.25% Domestically, it is usually called A3 steel. Internationally, it is generally called 1008, 1015, 1018, 1022, etc. Mainly used for 4.8 grade bolts and 4 grade nuts, small screws and other products without hardness requirements. (Note: Self-drilling screws mainly use 1022 material.)
2. Medium-carbon steel 0.25%<C%≤0.45% Domestically, it is usually called 35# and 45# steel, internationally generally called 1035, CH38F, 1039, 40ACR, etc. Mainly used for 8 grade nuts, 8.8 grade bolts and 8.8 grade internal hexagon products.
3. High-carbon steel C%>0.45%. Currently, it is basically not used in the market.
4. Alloy steel: Alloy elements are added to ordinary carbon steel to increase some special properties of the steel: such as 35, 40 chromium molybdenum, SCM435, 10B38. Fang Sheng screws mainly use SCM435 chromium molybdenum alloy steel, the main components include C, Si, Mn, P, S, Cr, Mo.
Stainless Steel. Performance grades: 45, 50, 60, 70, 80
Mainly divided into austenitic (18%Cr, 8%Ni) with good heat resistance, good corrosion resistance, and good weldability. A1, A2, A4
Martensitic, 13%Cr, with relatively poor corrosion resistance, high strength, and good wear resistance. C1, C2, C4 Ferritic stainless steel. 18%Cr has better cold heading properties and stronger corrosion resistance than martensitic stainless steel. Currently, imported materials on the market are mainly Japanese products. According to grade, they are mainly divided into SUS302, SUS304, and SUS316.
Copper. Commonly used material is brass...zinc-copper alloy. In the market, H62, H65, and H68 copper are mainly used for making standard parts.
