The steel 0

25C-1.1Cr-O. 7Mn-0. 25Mo-0.05V is melted by 60 t EBT arc fumace-LF-VD-8.4 t ingot casting process. The samples for thermal simulation are cut from 250 mm x 250 mm rolled bloom. The effect of temperature (ambient to 1 200℃) on mechanical properties of steel is tested by Gleeble-3800 thermal-simulated examination

and the continuous cooling transformation curves of steel with cooling speed 0. 1 ~35℃/s are got. And the mechanical properties of 200 mm x 200 mm bloom of steel with normalizing at 920℃

oil quenching at 880 - 900 °C and tempering at 630 〜680 °C by electric resistance furnace and salt bath furnace are examined. Results show that the steel has better ho

t working property at 900 ~ 1 200 °C ； as the cooling rate is more than 15℃ /s

the bainite + martensite structure could be got； and with normalizing at 920 T

oil quenching at 860℃ and tempering at 650 ~ 680 ℃

the yield strength R

P0.2

of steel 525 ~ 570 MPa

tensile strength R

m

710 -745 MPa

elongation A 22% ~23%

longitudinal impact energy (U- 5 mm) 68 ~82 J and transverse impact energy (U_ 5 mm) 65 ~ 76 J are obtained to meet the requirement of standard.