Effects of tempering process on microstructure and mechanical properties of G18NiMoCr3-6

In this article the effects of tempering temperature and tempering time on microstructure and mechanical properties of G18NiMoCr3-6 cast steel were studied. The results show that: the microstructure of G18NiMoCr3-6 treated by different tempering processes is tempered sorbite. When tempering temperature is within 510°C ∼630°C, the hardness and strength gradually decrease; the elongation and impact energy gradually increase with the increasing of the tempering temperature. The reason is that the tempering temperature increases the dislocation density decreases gradually, the martensite decomposes and the carbide precipitates, aggregates and grows. When G18NiMoCr3-6 is tempered at 600 °C for 60min∼120min, the microstructure is tempered sorbite. With the prolongation of holding time, the mechanical properties of G18NiMoCr3-6 changed little. (paper)