Abstract
The hot compression tests of Ti-12Mo-4Zr-5Sn alloy were tested on the thermo-mechanical simulator of Gleeble-3500 under isothermal and constant strain rate. We studied this alloy’s behavior during thermal deformation at the conditions of T = 670~820 °C, ε ˙ = 0.001~10 s−1, and deformation degree 70%. The rheological stress curves of the alloy were modified, the characteristics of the rheological stress curves were analyzed, and the activation energy map of hot deformation was established. A physical constitutive model of the alloy based on strain compensation was established, which has taken the relationship between Young’s modulus and self-diffusion coefficient and temperature into account. Moreover, the intrinsic hot workability ξ map of the alloy was established based on the polar reciprocity model. The results show that this alloy’s rheological stress will descend when the temperature of deformation rises and grow when the strain rate increases, and has negative sensitivity of temperature and positive sensitivity of strain rate. According to the error calculation, the physical constitutive model’s correlation coefficient is 0.9910 and the average relative error is 3.97%, which has good accuracy. Through the analysis of the microstructures of the instability zone and the stability zone, it was found that the instability mode of the instability zone was dominated by the local flow, and the deformation mechanism of the stability zone was dominated by the dynamic recrystallization. The optimum processing parameters of the alloy known from ξ map and metallographic structure are the following: T = 790~820 °C and ε ˙ = 0.001~0.01 s−1.
Highlights
Istics of the rheologKiceayl wstorersdss:cuTri-v1e2sMwoe-4reZra-n5aSlnyzaelldo,ya; npdhythsiecaalcctiovnasttiiotuntievneemrgoydmela; poolfar reciprocity model; intrinsic hot Ttiio-1n2Mwaos-4Zesrt-a5bSlnisahlewldooy.r;kApahbpyilhsityiycsaiξlcamcloancpostnitsutittiuvteivmeomdeold; eploloafr trheeciparlolocyitybamsoeddeol;ninsttrrianisnic nlitwy aξsmeastpablished, which has taken the relationship between Young’s modulus and coefficient and temperature into account
The intrinsic hot workability ξ lloy was established based on the polar reciprocity model
There have been many reports on the application of the constitutive model to exploring the thermal deformation behavior of titanium alloy [7,8], but most of the constitutive models are based on Arrhenius constitutive equation, which belongs to the macroscopic phenomenological constitutive model
Summary
The nominal composition of experimental material is Ti-12Mo-4Zr-5Sn. The chemical compositions (wt.%) of this alloy are: Mo 12%, Zr 4%, Sn 5%, and the rest Ti. The hot compression of small cylindrical specimens with Φ 8 mm × 12 mm obtained from raw ingot was tested on the thermo-mechanical simulator of Gleeble-3500 (Dynamic Systems Inc., Portland, OR, USA). Thereafter, the compression tests were conducted at different strain rates (0.001, 0.01, 0.1, 1 and 10 s−1) with a compression rate of 70%. When the reduction in the height reached 70%, to retain the deformation microstructure, the specimen should be quenched immediately. The flow diagram of hot compression deformation is shown, which shows four stages: heating, holding, compression, and quenching. Specimens for the compression testing were sectioned parallel to the deformation axis and the cut sides were used for metallographic examination after polishing. Microstructure characterizations were observed through FL7500 optical microscope (Jinan Metallographic Instrument Equipment Co., Jinan, China) after etching by the solution of 6%HNO3 + 4%HF + 90%H2O (vol.%)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
