At present, the main material of screw is carbon steel, stainless steel, and copper.
For carbon steel, it has low carbon steel, medium carbon steel, high carbon steel and alloy steel by the carbon content of carbon steel.
1 Low carbon steel C%≤0.25% It is usually called A3 steel in China. It is called 1008, 1015, 1018, 1022 and so on. Mainly used for 4.8 bolts, 4 nuts, small screws and other products without hardness requirements. (Note: Drilling nails are mainly made of 1022 material.)
Medium carbon steel 0.25%
3 High carbon steel; 0.45%. Rarely used in the market
Alloy steel: Add alloy elements to ordinary carbon steel to increase some special properties of steel, such as 35, 40 chromium molybdenum, SCM435, 10B38, etc. Fangsheng screws mainly use SCM435 chromium-molybdenum alloy steel, containing C, Si, Mn, P, S, Cr, and Mo.
Two stainless steel. Performance level: 45, 50, 60, 70, 80
1 Key Points Austenite (18%Cr, 8%Ni) has good heat resistance, good corrosion resistance, and good weldability. A1, A2, A4
2 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 and corrosion resistance than martensite. Imported materials on the market mainly come from Japan. SUS302, SUS304, SUS316 grades.
Three coppers. Common materials are brass...zinc-copper alloy. H62, H65, and H68 copper are mainly used as standard parts in the market.