Commonly used fastener materials

First of all, the main standard components currently on the market are:
Carbon steel (including easy iron and steel), stainless steel (including free-cutting stainless steel), copper (including high-speed cutting copper).

(A) Carbon steel. We distinguish the carbon content of mild steels, medium carbon steels and high carbon steels as well as alloy steels and carbon steels.
1. Low carbon steel C% ≤ 0.25% Known as A3 steel in Japan. Foreign countries are basically called 1008,1015,1018,1022 and so on. It is mainly used for products that do not have hardness requirements such as 4.8 bolts and 4 nuts and small screws. (Note: The drill is mainly made of 1022 material.)
2. Medium carbon steel 0.25% <C% ≤ 0.45% As No.35 and No.45 steels in Japan, they are basically called 1035, CH38F, 1039, 40ACR overseas. It is mainly used for 8 grade nuts, 8.8 volts and 8.8 grade hexagonal products. 3, high carbon steel C%> 0.45%. Currently not used in the market
4, Alloy steel: Add alloying elements of common carbon steel and add some special properties of steel such as 35,46 chrome molybdenum, SCM435, 10B38. Fangsheng screws are mainly made of SCM435 chrome-molybdenum alloy steel and the main components are C, Si, Mn, P, S, Cr and Mo.

(B) Stainless steel. Performance level: 45,50,60,70,80
It is mainly divided into austenite (18% Cr, 8% Ni), good heat resistance, good corrosion resistance, and good weldability. A1, A2, A4
Martensite and 13% Cr have low corrosion resistance, high strength, and good wear resistance. C1, C2, C4 ferritic stainless steel. 18% Cr has good forging properties and is more resistant to corrosion than martensite. The materials currently imported to the market are mainly Japanese products. According to the grade, it is mainly divided into SUS302, SUS304 and SUS316.

(C) Copper. Common materials for brass … Zinc-Copper alloy. The market mainly uses H62, H65 and H68 copper as standard parts.

Third, the effects of various elements of the material on the properties of steel:
1. Carbon (C): Improves the strength of steel materials, especially heat treatment properties, but as the carbon content increases, the plasticity and toughness decrease, affecting the low temperature progress and weldability of steel parts.
Manganese (Mn): Improves the strength of steel and improves hardenability to some extent. That is, the strength of hardening penetration increases during quenching, and manganese can also improve surface quality, but excess manganese is detrimental to ductility and weldability. It also affects the control of plating during the plating process.
3. Nickel (Ni): Improves steel strength, improves low temperature toughness, improves corrosion resistance, ensures stable heat treatment effect, and reduces hydrogen embrittlement.
4, Chromium (Cr): Helps improve hardenability, improve wear resistance, improve corrosion resistance and maintain strength at high temperatures.
5, Molybdenum (Mo): Helps control hardenability, reduces brittleness of steel, and has a great effect on tensile strength at high temperatures.
Boron (B): Helps improve hardenability and heat treat low carbon steels to produce the desired reaction.
7. Niobium (V): Refines austenite grains to improve toughness.
8, Silicon (Si): To ensure the strength of steel, the proper content can improve the plasticity and toughness of steel.

(B) Relationship between the main chemical composition and the performance of stainless steel.
Carbon C can increase hardness and strength. Excess amounts reduce its ductility and corrosion resistance.
2. Chromium can improve corrosion resistance, oxidation resistance, grain refinement, strength, hardness and wear resistance
3. Ni Ni can increase high temperature strength and corrosion resistance and reduce cold work hardening rate.
4. Molybdenum and molybdenum increase strength and have excellent corrosion resistance against oxides and seawater.
As shown in Figure 5, copper Cu helps with cold forming and reduced magnetic properties.