Abstract: A new approach to determining the thermomechanical parameters of forging processes is proposed based on the dissipative structure theory and the dynamic material model(DMM). This approach is used to identify the process window within which the properties and microstructures of the forgings are essentially stable and can thus be controlled during the forging processes. The procedure of applying the proposed method to detemine the process window of GH169 alloy is illustrated in detail. Moreover, some graphs valuable for determining the process parameters of GH169 alloy forging processes using hammer or press are also presented for the first time. The results of this study indicate that for producing high quality GH169 alloy forgings, it is appropriate to perform the finish forging at a lower temperature using equipment with mediate strain rate.

Key words: heat resistant alloys, forging　thermomechanical parameters, stability