Carbon Steel, Alloy Steel and Special Steel, Raw Materials of Fasteners

1. Bolts, screws, studs: if the strength grades are 3.6, 4.6, 4.8, 5.6, 5.8, 6.8, generally selecting the carbon steel to produce bolts, screws and studs, without heat treatment; if the grade of 8.8, 9.8, to choose low carbon alloy steel or medium carbon steel as the raw material, then have quenching and tempering processes; 10.9 grade fasteners typically use low, medium carbon alloy steel or alloy steel, and need quenching and tempering; 12.9 grade fasteners normally are made from alloy steel, also require quenching and tempering processes.

2. Pop nuts: clinch nuts of strength grades of 4, 5, 6 commonly are made of carbon steel, can also be made of free cutting steel, and without heat treatment; 8, 9 grades rivet nuts general pick up carbon steel as the material, then have quenching and tempering; rivet nuts in 10, 12 grades, in order to improve the mechanical properties, if necessary, will add alloying elements, also need quenching and tempering.

3. Tightening screws: 14H typically use carbon steel as the raw material, and without heat treatment; 22H, 33H also use the carbon steel, need quenching and tempering; 45H tightening screw general is made from alloy steel, and needs quenching and tempering.

4. Self-tapping screw: it is made of the carbon steel, the outer surface needs to have carburizing treatment.

5. Flat washer: HV140 flat washer generally uses low carbon steel as the raw material; the medium carbon steel is selected to produce HV300 washer, and the heat treatment is needed.