The Study On Constitutive Relation And Processing Map For TC21Titanium Alloy Of Damage Tolerance Type

Titanium alloy is very important lightweight structural material, and it has goodlow temperature performance and heat resistance. Meanwhile, it has highlightadvantages of excellent corrosion resistance and high specific strength. TC21titaniumalloy is a new generation of materials, which meets new aircraft the requirement ofdamage tolerance to design and development. In this paper, TC21titanium alloy as theresearch object, mainly from the constitutive relation and the processing map to carry onstudying.Firstly, in this paper, hot compression experiments on TC21alloy were conductedwith Gleeble-3500thermal simulator at deformation temperature870～990℃andstrain rate0.001～10s-1, the data gained from experiments as the basis of study of thematerial. The constitutive relation of TC21titanium alloy is established based on BPneural network. The results show that training simulation method has a high predictionprecision and good description in the complicated non-linear relationship betweenthermodynamic parameters, which provide good data resources for the future furtherresearch and development of TC21titanium alloy.Secondly, Prasad and Murty criterion are respectively used to draw the processingmap of TC21titanium alloy based on dynamic material model principle, and theadvantages and disadvantages of common plastic instability criteria are analyzedcomparatively. By observing the processing maps, what can be seen that illustrating thevariation of the efficiency of power dissipation and flow instability area withtemperature, strain rate and strain. Moreover, all kinds of deformation mechanisms andmicrostructure evolution are analyzed for the TC21titanium alloy during the thermaldeformation.Finally, through strict simulation and experiment, the results indicate that thesuitable processing conditions of TC21titanium alloy are temperature from870℃to990℃, strain rate from0.001s-1to0.25s-1. The tress-strain curves have obviouslysoftened phenomenon in the temperature region from870℃to990℃. In addition, theinstability domain of hot processing for TC21titanium alloy approximately containsfour areas, that is,①870℃～990℃,0.25s-1～10s-1②950℃～985℃,0.1s-1～0.25 s-1③885℃～910℃、0.001s-1～0.0045s-1④927℃～990℃、0.001s-1～0.0025s-1.