The current market standard parts mainly carbon steel, stainless steel, copper three kinds of materials
1. Carbon steel. We distinguish low carbon steel, medium carbon steel, high carbon steel and alloy steel by the carbon content of carbon steel material.
(1) low carbon steel C%≤0.25% is usually known as A3 steel. Foreign basically called 1008,1015,1018,1022 and so on. Mainly used for 4.8 grade bolts and 4 grade nuts, small screws and other products without hardness requirements. (Note: Tail-drilling nails are mainly made of 1022 material.)
(2) Medium carbon steel 0.25%< C%≤0.45% is usually referred to as 35, 45 steel at home, and basically referred to as 1035, CH38F, 1039,40 ACR abroad. It is mainly used for class 8 nuts, class 8.8 bolts and class 8.8 inner hexagonal products.
(3) high carbon steel C%> 0.45%. It's barely on the market right now.
(4) alloy steel: in the general carbon steel to add alloy elements, increase some special properties of steel: such as 35, 40 chromium molybdenum, SCM435, 10B38. Fangsheng screws mainly use SCM435 chromium molybdenum alloy steel, the main components are C, Si, Mn, P, S, Cr, Mo.
2. Stainless steel. Performance levels: 45,50,60,70,80.
Main 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 ability and corrosion resistance than martensite. At present, imported materials on the market are mainly Japanese products. There are three levels: SUS302, SUS304, and SUS316.
Class 4.8 hex bolts: 1008K, 1010, 1015K.
Class 6.8 hex bolts: 1032, 1035, 1040, CH38F, 1039.
Class 8.8 hex bolts: 1035ACR (below M10) 1040ACR (above M12) CH38F, 1045ACR, 1039 10B21, 10B33, 10B38.
Class 8.8 hex socket bolts: CH38F, 1039, 10B21 (M10-M12), 10B33, (M14) 10B38 (M12-M24) 10B21.
Hexagon bolts of grade 10.9:1045ACR, 10B38.
│8│ Class nuts: 1008K, 1010.
Class 8 nuts: 1015 (M< 16), CH38F (M≥16).
Class 10 nuts: CH38F, 1039, 10B21, 10B33.
Class 12 nuts: 1039, 10B21, 10B33, 10B38.
Carriage screw: 1008, 1010, 1015.
Hex flange convex bolts: CH38F, 1039, 10B21, 10B33, 10B38.
Hexagon wood screw: 1008K, 1010.
Self-tapping nails, wallboard nails, drill nails, splint nails: 1018, 1022, CH22A.
Machine screw, furniture screw: 1008, 1010.
3. The copper. The common material is brass. Zinc copper alloy. The main market with H62, H65, H68 copper standard parts.
The influence of various elements in the material on the properties of steel
1. carbon (C) : improve the strength of steel, especially its heat treatment performance, but with the increase of carbon content, plasticity and toughness decrease, and will affect the cold heading performance and welding performance of steel.
2. manganese (Mn) : improve the strength of steel parts, and to a certain extent, improve the quenchability. That is, it increases the strength of hardening infiltration during quenching, and manganese can also improve the surface quality, but too much manganese is not good for ductility and weldability. And it will affect the control of plating.
3. nickel (Ni) : improve steel strength, improve toughness at low temperature, improve atmospheric corrosion resistance, and can ensure stable heat treatment effect, reduce the role of hydrogen embrittlement.
4. chromium (Cr) : can improve quenchability, improve wear resistance, improve corrosion resistance, and is conducive to maintaining strength at high temperature.
5. molybdenum (Mo) : can help control the quenchability, reduce the sensitivity of steel to temper brittleness, has a great impact on improving the tensile strength at high temperature.
6. boron (B) : can improve the quenchability, and help to make low carbon steel to heat treatment produce the expected reaction.
7. alum (V) : refine austenite grain, improve toughness.
8. silicon (Si) : ensure the strength of steel parts, appropriate content can improve the plasticity and toughness of steel parts.
