The influence of sizing deformation temperature (820 ~ 920 °C )

deformation extent (0. 18 ~ 0. 24) and cooling rate (0. 2 ~2. 1 ℃/s) on structure

tensile strength and impact energy of steel 40Mn2V (/% : 0. 41C

0. 22Si

1.65Mn

0.014P

0. 005S

0. 15V

0.021Ti

0.008 0N) for N80-1 seamless casing tube (Φ139. 70 ~ 339. 72 mm x 6. 20 ~22. 22 mm) is systematically analyzed by hot simulation test

and a math model is established. Results show that at defined sizing deformation temperature

as cooling rate of steel is higher than a critical value

the bainite transformation occurs in structure led to poor impact toughness of steel; steel 40Mn2V is available for the tube size with cooling rate less than 1. 1 ℃/s

the suitable process parameters are that as cooling rate less than 0. 6 ℃/s

the sizing temperature is 695 ~870℃

and as cooling rate 0. 6 ~ 1. 1 °C/s

the sizing temperature is 695 ~ 820 ℃.