The Usage of Hex Bolts

August 01,2022

Hexagon bolts are widely used both indoors and outdoors. The outdoor ones are mostly used in building installations, bridges, roads, power facilities, etc.; the indoor ones are mostly used in mechanical equipment, medical equipment, electronic instruments, etc.


Hex Bolts


Where are the hex bolts used?


When the outer hexagon bolts are used in buildings, bridges, etc., high-strength outer hexagon bolts are selected, and generally grade 10.9 or above is selected, because this kind of place requires good fastening performance and good heavy performance. . In order to enhance the anti-loosening performance, a washer is generally used.


When the outer hexagon bolts are used in electronic instruments, medical instruments, etc., stainless steel outer hexagonal bolts are generally selected, because the surface color of the stainless steel material is more beautiful, and the corrosion resistance is better, which can keep the machine beautiful for a long time. For large mechanical equipment, it is recommended to choose high-strength outer hexagon bolts.


At present, there are three main materials of hexagon socket head cap screws on the market: carbon steel, stainless steel and copper.


Carbon steel


We distinguish low carbon steel, medium carbon steel and high carbon steel and alloy steel by the carbon content in carbon steel material.


  • Low carbon steel C%≤0.25% is usually called A3 steel in China. Foreign countries are basically called 1008, 1015, 1018, 1022, etc. Mainly used for grade 4.8 bolts, grade 4 nuts, small screws and other products without hardness requirements. (Note: The drill tail screw is mainly made of 1022 material.)
  • Medium carbon steel 0.25% 0.45%. It is basically not used on the market.
  • Alloy steel: Add alloying elements to ordinary carbon steel to 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.

Stainless steel


Performance grade: 45, 50, 60, 70, 80 Mainly divided into austenite (18% Cr, 8% Ni) with good heat resistance, good corrosion resistance and good weldability. A1, A2, A4? Martensite and 13% Cr have poor corrosion resistance, high strength and good wear resistance. C1, C2, C4 ferritic stainless steel. 18%Cr has better upsetting and corrosion resistance than martensite.


At present, the imported materials on the market are mainly Japanese products. According to the level, it is mainly divided into SUS302, SUS304 and SUS316.




The common material is brass. Zinc copper alloy. The market mainly uses H62, H65, H68 copper as standard parts.