1 Carbon steel. We distinguish low-carbon steel, medium-carbon steel, high-carbon steel, and alloy steel based on the carbon content of carbon steel materials.

1.1 Low carbon steel C% 0.25% is usually called A3 steel in China. It is basically called 1008, 1015, 1018, 1022, etc. abroad. Mainly used for grade 48 bolts, grade 4 nuts, small screws and other products without hardness requirements. (Note: 1022 material is mainly used for drill tail screws.

1.2 Medium carbon steel 0.25%<C%<0.60% is usually called No. 35 and No. 45 steel in China, and basically called 1035, CH38F, 1039, etc. abroad. Mainly used for grade 8 nuts, grade 8.8 bolts and grade 8.8 inner hexagon products.

1.3 High carbon steel C% 20.60%. Basically not used in the market at present.

14 Alloy steel: Add alloy elements to ordinary carbon steel to increase some special properties of steel: such as 35, 40 chromium molybdenum, SCM435, 10B38, Fangsheng 12.9 grade screws mainly use SCM435 chromium molybdenum alloy steel, the main components are C.Si, Mn.

2 Stainless steel. Performance grade: 45, 50, 60, 70, 80 mainly divided into austenite (18%Cr, 8%Ni), good heat resistance, good corrosion resistance, and good weldability. A1, A2, A4 martensite (13%Cr) has poor corrosion resistance, high strength and good wear resistance. C1, c2, c4 ferritic stainless steel. 18%Cr shovel has better forgeability and better corrosion resistance than martensite. Currently imported materials on the market are mainly Japanese products. According to the grade, it is mainly divided into SUS302, SUS304 and SUS3163 copper. Commonly used materials are brass and zinc-copper alloy. The market mainly uses H62, H65, H68 copper as standard parts.

3 Aluminum alloy has low density, but relatively high strength, close to or exceeds high-quality steel, good plasticity, can be processed into various profiles, has excellent electrical conductivity, thermal conductivity and corrosion resistance, is widely used in industry, and the amount of use is second only to steel.