Effect of heat treatment process on microstructure and properties of S47450 bolt

The effects of heat treatment process on the microstructure and mechanical properties of S47450 bolt materials were studied by optical microscope (OM), scanning electron microscope (SEM), X-ray diffraction (XRD), tensile test, impact test and hardness test. The results showed that in the temperature range selected by the test, the quenched martensite of the bolt material after quenching at 1070 °C and tempering at 670 °C was fully refined and evenly distributed, and the precipitation of Cr 23 C 6 played the role of precipitation hardening. It showed the excellent comprehensive mechanical properties, with the Brinell hardness reaching 295 HBW and the tensile strength of 1035 MPa. The elongation was 16 %, and the impact energy at room temperature was 21 J.