Microstructure evolution and mechanical properties of severely deformed TA15 alloy by multi‐directional forging and annealing. Issue 5 (5th May 2022) - Xue, K.M.
Abstract: Multi‐directional forging technology, as a representative severe plastic deformation technology, is urgent to be developed because it has strong microstructure refinement and performance improvement effects. In this paper, multi‐directional forging experiments of TA15 titanium alloy with different passes were carried out at 700 °C using unrestricted multi‐directional forging die structure. Then the samples of TA15 titanium alloy after multi‐directional forging deformation were subjected to a high‐temperature vacuum annealing treatment. The test results reveal TA15 alloy was effectively refined through multi‐directional forging without any cracking with the increasing of deformation passes. The mechanism of grain refinement during multi‐directional forging included dynamic recrystallization, grain crushing and adiabatic shear deformation bands refinement. The amount and grain size of recrystallization grains increased when the annealing time increased from 1 hour to 4 hours. Supplemented by annealing, the adiabatic shear deformation bands microstructure with the mixed microstructure of coarse αp and fine αs were obtained and the hardness after multi‐directional forging and annealing was investigated. The yield strength and ultimate tensile strength increased by 26.1 % and 25.5 % respectively when the deformation pass increased to 3 passes compared with the initial specimen. The present work revealed that multi‐directional forging deformation combined with appropriate annealing could represent an efficient route to improve the microstructure and mechanical property of TA15 alloy. Abstract : The TA15 alloy microstructures and mechanical properties in different deformation zones during multi‐directional forging and annealing were investigated. The present work revealed that multi‐directional forging deformation combined with appropriate annealing could represent as an efficient route to improve microstructure and mechanical property of TA15 alloy.