The relationship between material and hardness of screws
Screws are commonly found in machinery, electrical appliances and buildings. They are usually made of metal. They are cylindrical and have grooves carved into the surface, such as an inclined plane around the side of the screw, to allow the screw to fasten the nut or other objects. The top diameter of the screw is large and can be round or hexagonal to allow tools such as a screwdriver or wrench to turn the screw. The protruding top also prevents the screws from drilling too deeply through the material and increases the screw pressure on the material.
At present, the screw standard materials mainly include copper screws, carbon steel screws, stainless steel screws three materials. When it comes to the material of screws, it may be necessary to consider the hardness and strength of screws when there are special uses. Materials should be considered when choosing screws.
- Copper screws
Common materials for brass – zinc – copper alloy.
- Carbon steel screws
We differentiate low carbon steel, medium carbon steel and high carbon steel and alloy steel by the carbon content of carbon steel material.
- Low carbon steel C%≤0.25% is basically called 1008,1015,1018,1022, etc. Mainly used for 4.8 class screws, 4 class nuts, small screws and other products without hardness requirements. (Note: 1022 material is mainly used for drilling tail nails.)
- Medium carbon steel 0.25%0.45%. It is not used in the market at present
- Alloy steel screws: Add alloy elements to common carbon steel to increase some special properties of steel.
- Stainless steel screws
Main components of austenite: good heat resistance, corrosion resistance, good weldability. Martensite, 13%Cr poor corrosion resistance, high strength, good wear resistance. C1, C2, C4 ferritic stainless steel. 18%Cr upsetting has better corrosion resistance than martensite.