Optimisation Of The Open Billet Process For Cast TA15 Titanium Alloy

In recent years,China’s economic level and science and technology have developed rapidly.The emergence of new technologies(e.g.,new energy technologies,biotechnology,microelectronics,precision manufacturing technologies,aerospace technologies,and ocean exploration and development)has caused structural changes between traditional production methods and new technologies.However,these changes are also placing greater demands on the level of development of basic industries worldwide to achieve higher standards of lightness,integration and economy.Titanium alloys play a very important role in the development of basic industries as a structural metal.TA15(Ti-6.5Al-2Zr-1Mo-1V)titanium alloy belongs to a high-alumina near-alpha titanium alloy,which contains molybdenum,vanadium and other beta-stable elements and has been widely used in the aerospace industry.At present,titanium alloy manufacturing is mainly formed by casting,by opening the ingot and then carrying out subsequent precision machining to obtain the final product that people need.However,this series of processes is still optimised by people repeatedly carrying out practical operations to optimise the processing process,which goes against the requirements of today’s industrial development for high quality,low consumption and efficient development.Therefore,this study takes cast TA15 titanium alloy as the research object,based on the experimental data obtained from the hot compression test,the high temperature deformation behavior of the alloy is studied,and the dynamic recrystallization critical strain model and volume fraction prediction model of cast TA15 titanium alloy are established with the help of the deformed specimens from the hot compression test and the experimental data,and the constructed prediction model is embedded into DEFORM-3D simulation through secondary development software to predict the dynamic recrystallization that occurs during the high temperature deformation of the material for the purpose of guiding the actual production.The following details of the study are presented:(1)Based on the hot compression simulation experiments,the high temperature deformation behavior of cast TA15 titanium alloy was studied,the intrinsic constitutive equations were constructed,the strain rate sensitivity exponent and strain hardening exponent of cast TA15 titanium alloy were calculated and analyzed based on the experimental data,the hot processing diagram of cast TA15 titanium alloy was drawn,and the microstructure obtained from the hot compression simulation tests was analyzed to determine the reasonable high temperature deformation processing range of the alloy.(2)By observing the microstructure of the specimens after deformation in hot compression tests,the dynamic recrystallisation volume fraction characteristics of the material were extracted with the aid of image analysis software,and a predictive model for the dynamic recrystallisation volume fraction of cast TA15 titanium alloy was established.(3)The secondary development of DEFORM-3D,based on the Fortran compiler,enables the visualisation of the dynamic recrystallisation volume fraction distribution during the high temperature deformation of cast TA15 titanium alloys by embedding user-defined target subroutines,providing some guidance for the development of practical open billet forging production processes for titanium alloys.