Materials are selected based on the strength grade of bolts: currently, the standard fasteners in the market mainly include carbon steel, stainless steel, and copper.
▌ Carbon Steel
We differentiate low carbon steel, medium carbon steel, high carbon steel, and alloy steel based on the carbon content in the carbon steel.
A. Low carbon steel C% ≤ 0.25% is commonly known as A3 steel in China. It is basically referred to as 1008, 1015, 1018, 1022, etc., abroad. It is mainly used for grade 4.8 bolts, grade 4 nuts, small screws, and other products without hardness requirements. (Note: Self-drilling screws are mainly made of 1022 material);
B. Medium carbon steel 0.25%;
C. High carbon steel C% > 0.45%. It is rarely used in the market currently;
D. Alloy steel: Alloy elements are added to plain carbon steel to enhance some special properties of the steel, such as 35, 40 chromium-molybdenum, SCM435, 10B38. Fengsheng screws mainly use SCM435 chromium-molybdenum alloy steel, whose main components include C, Si, Mn, P, S, Cr, Mo.
▌ Stainless Steel
Performance grades:
A. 45, 50, 60, 70, 80 mainly include austenitic (18%Cr, 8%Ni) with good heat resistance, good corrosion resistance, and good weldability;
B. A1, A2, A4 martensitic 13%Cr with poor corrosion resistance, high strength, and good wear resistance;
C. C1, C2, C4 ferritic stainless steel. 18%Cr has good formability and stronger corrosion resistance than martensitic;
D. Currently, the imported materials in the market are mainly Japanese products. They are mainly classified by grades as SUS302, SUS304, SUS316.
▌ Copper
The commonly used materials are brass and zinc-copper alloy. The market mainly uses H62, H65, H68 copper for standard fasteners.
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