Ti551两相区变形本构模型及热加工图OA

As a base material for additive forging processes,a novel titanium alloy Ti551 had been used to conduct hot compression via a Gleeble 3500 thermo-mechanical simulator,and then flow stress curves were obtained over a strain rate range of 0.001～10 s-1 and a temperature range of 700～900℃in this study.The flow stress curves were fitted using a strain-compensated Arrhenius model and an arti-ficial neural network model,respectively.The strain-stress curves indicate that during deformation in the two-phase region,the flow stress of the Ti551 alloy exhibits a typical post-peak softening behavior under medium-to-low temperatures and high strain rates.Compared with predicated results from the strain-compensated model,the artificial neural network model gives higher prediction accuracy and lower average absolute relative error under low-temperature and high strain-rate conditions,with a cor-relation coefficient R of 0.992 2 and a mean average absolute relative error of 6.3%.Based on the con-structed hot processing map of the Ti551 alloy deformed in the two-phase region,the plastic instability domains under different strain conditions were identified.The lower limit of equivalent strain rate dur-ing forging in the α+β two-phase region should be no less than 0.01 s-1,corresponding to an actual for-ging speed of not less than 10 mm/s,and that the final forging temperature should be no lower than 750℃.These finds can help design practical forging parameters and numerical simulation of Ti551 alloy in the α+β two-phase region.