The hot deformation behaviors of low carbon steel QD08 were investigated by hot compression tests at temperatures from 1 000 to 1 200 ℃ and strain rates from 0. 1 to 10 s

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. In order to describe the flow characteristics

a constitutive equation was established. Based on dynamic materials model and Prasad’s instability criterion

the power dissipation map and the instability map were drawn. The processing map was obtained by superimposition of the power dissipation and the instability maps as well as the regions having the lowest strain rate sensitivity added for more clarification of low and high workability regions. The microstructure of the low carbon steel QD08 was analyzed to correlate with the processing maps. The results show that the safe domain of hot deformation for low carbon steel QD08 is mainly at the temperature range in 1 070 ～1 100 ℃

and strain rate range of around 5～10 s

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. By the metallographic observations

the grain is refiend by DRX under the stable deformation conditions.