Behaviour of thermal deformation of steel Cr5 (% ：0.85C

5.0Cr

0.6Si

0.5Ni

0.4Mo

0.1V) with stain rate 0.001 〜1 s-1 at 900 ~ 1200 °C has been studied by using Gleeble-3500 thermal simulator. The apparent activation energy Q for steel Cr5 is 307 kJ/mol. The thermal deformation equation for steel Cr5 is given to characterize the dependence of peak stress of thermal deformation on temperature and strain

and its processing map is established. With increasing deformation temperature and decreasing strain rate

the efficiency η of power dissipation increases

and with true strain 0. 7 and strain rate 0.001 sat 1100 °C the efficiency of power dissipation is up to peak value that is about 40%.