With the help of optical microscope(OM)

scanning electron microscope (SEM)

transmission electron microscope(TEM)

X-ray diffractometer (XRD)and other equipment

through mechanical performance testing and microstruc- ture observation

we explored the effects of furnace cooling

water cooling

and asbestos slow cooling three different cooling methods on the structure and properties of the hot-rolled condition C61 steel

compared the performance of the test steel in different conditions. The experimental results show that the cooling rate has a great influence on the performance of the test steel. Due to V

water cooling

＞ V

asbestos slow cooling

＞ V

furnace cooling

the st

rength and hardness of the test steel under water cooling condition are higher than those of furnace cooling and asbestos slow cooling. After hot rolling and water cooling

the tensile strength(Rm)and reduction of area(Z%)of the test steel are 1450 MPa and 62.7%

XRD analysis shows that the residual austenite content of the steel increases with the increased cooling rate after hot rolling

and the surface-centered cubic austenite is conducive to improve the toughness of the test steel. It can be seen that the test steel after hot rolled + water cooling was heated at 950 ℃ for 1 h quenched by water

and cold treatment at -73 ℃ for 1 h

then returned to room temperature

finally tempering at 482 ℃ for 16 h

air cooling to room temperature is the best process scheme.