The test steel GCrl5 ( % ： 0. 97 - 1.03C

1. 43 - 1. 59Cr) is melted by a 10 kg vacuum induction furnace and added 0. 1 % ~0. 3% nitrogen in steel by silicon nitride at argon atmosphere. The tensile test of the forged steel at 700 ~ 1 150 °C has been carried out by using a Gleeble-1500 thermal simulation machine

and the morphology of fracture and longitudinal structure is observed by scanning electron microscope and optical microscope. Results show that nitrogen in steel is in the form of solution ； and with increasing nitrogen content

the reduction of area of the steel at elevated temperature increases obviously while the peak stress of the steel increases slightly.