The 50% hot deformation test on pipeline steel X52 (L360) ( % ： 0. 08 C

0. 20Si

0. 93 Mn

0. 024Als

0. 02Nb

0. 02Ti) with strain rate 0. 01 ~ 10 s

-1

at 950 ~ 1 200 °C was carried out by Gleeble-3500 thermal simulator to get true stress-strain curves. Based on regression analysis

the activation energy and equation of hot deformation of steel X52 is defined and the effects of strain rate

temperature and Z parameter on peak stress of hot deformation are obtained. Results show that with decreasing the defbimation temperature

the peak stress increases and moves in the direction of strain increment

and with increasing the strain rate

the peak stress increases and also moves in the direction of strain increment ； the activation energy of hot deformation of steel X52 is 232 kJ/mol; and with increasing Z parameter T the peak stress of hot deformation increases.