Hardening Process Of Screws

The following are several common screw-hardening processes:

1. Carburizing treatment
Carburizing treatment is to heat the screws in a carbon-containing atmosphere to allow carbon atoms to penetrate into the surface layer of the screws. After quenching and tempering, the surface layer becomes very hard, while the core remains tough.

Features: Improve surface hardness and wear resistance while maintaining the toughness of the core.

Application: Suitable for screws that require high surface hardness and wear resistance, such as screws in automobiles and mechanical equipment.

2. Nitriding treatment
Nitriding treatment is to heat the screws in a nitrogen or ammonia environment to allow nitrogen atoms to penetrate into the surface of the screws to form a hard nitride layer.

Features: Extremely high surface hardness, good wear resistance, and corrosion resistance.

Application: Widely used in high-demand mechanical parts, such as engine parts and high-strength screws.

3. Quenching and tempering
Quenching is to heat the screw to a high temperature and then cool it quickly to increase its hardness. Tempering is to reheat the quenched screw to a certain temperature and keep it for a period of time to reduce its brittleness.

Features: Improve overall hardness and strength, while reducing brittleness and enhancing toughness.
Application: Suitable for all kinds of screws that require high strength and toughness, such as construction screws and industrial machinery screws.

4. Induction heating
Induction heating is to use the electromagnetic field generated by a high-frequency current to heat the surface of the screw, and then quickly cool it to harden the surface layer.

Features: Fast heating speed, controllable hardening layer depth, suitable for mass production.
Application: Used for screws that require local hardening, such as automotive and home appliance screws.

5. Blackening treatment
The blackening treatment is to heat the screw in an alkaline solution to form a black oxide film, increase surface hardness and improve rust resistance.

Features: Improve surface hardness and corrosion resistance, while enhancing appearance.
Application: Widely used in various machinery and tool screws.