Requirements for fixture materials of tensile testing machines

For general metal and non-metallic specimens, the jaws of the fixture are in direct contact with the specimens. Generally, high-quality alloy structural steel, alloy high-carbon steel or low-carbon alloy steel, cold-work mold steel, etc. are used to increase their strength and wear resistance through appropriate heat treatment processes. Sometimes special steel is also installed at the jaws, or gold steel sand is sprayed on the surface of the jaws (suitable to clamp harder metal materials, such as steel strands, etc.).
For some fixtures with small test force, the surfaces in contact with the sample are made of soft rubber. (For example: the clamping surface of plastic film, fiber wire and other samples,)
The specific clamps generally use high-quality medium-carbon steel and alloy structural steel to increase their mechanical properties through appropriate heat treatment processes. Sometimes, non-ferrous metals such as aluminum alloys and special metals are used in order to reduce weight. Sometimes cast structure cast steel, cast aluminum, etc. are also used.