Abstract：A new high strengthened no-heated treatment free cutting steel used in fracture splitting connecting rod was studied. Microscope, SEM were used to investigate the microstructure and precipitated phase, including the connection between them and the mechanical properties. The results showed that the studied steel was made of ferrite and pearlite, when adding mass V and N to the steel it was benefit to offer a mount of precipitated phase and improve the strength. By accelerating the cooling rate after rolling it could make the ferrite thinner, pearlite group and the distance between pearlite flake smaller, precipitated phase more, whats more, it attained tensile strength and yield strength up to 1000MPa and 750MPa.
2009, Vol. 44 
