Material of hex head bolts
At present, there are three main materials for hexagon socket screws on the market: carbon steel, stainless steel, and copper.
(1) Carbon steel hex head bolts. We distinguish low carbon steel, medium carbon steel and high carbon steel and alloy steel by the carbon content in the carbon steel material.
1. Low carbon steel C%≤0.25% hex head bolts is usually called A3 steel in China. Foreign countries are basically called 1008, 1015, 1018, 1022 and so on. It is mainly used for products without hardness requirements such as grade 4.8 bolts, grade 4 nuts, and small screws (Note: 1022 material is mainly used for drilling screws).
2. Medium carbon steel 0.25% 0.45%. It is basically not used in the market at present.
3.Alloy steel hex head bolts: Add alloy elements to ordinary carbon steel to increase some special properties of steel: such as 35, 40 chromium molybdenum, SCM435, 10B38. Fangsheng screws mainly use SCM435 chrome-molybdenum alloy steel, the main components are C, Si, Mn, P, S, Cr, Mo.
(2) Stainless steel hex head bolts. Performance grade: 45, 50, 60, 70, 80 Mainly divided into austenite (18%Cr, 8%Ni), good heat resistance, good corrosion resistance, 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 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) Copper hex head bolts. Commonly used materials are brass-zinc-copper alloys. H62, H65 and H68 copper are mainly used as standard parts in the market. Plates used in carbon steel products: No. Type Available materials 1 Grade 4.8 hexagonal screw 1008K 1010 1015K 2 Grade 6.8 hexagonal screw.