Study on deformation and fracture behavior of TC17 titanium alloy by finite element model based on mapping EBSD data

Abstract

TC17 titanium alloy is widely used in the aviation industry due to its high strength, high hardness, excellent fatigue resistance, and corrosion resistance. As a two-phase alloy, the plastic strain accommodation at α/β phase interfaces governs the material’s overall plastic deformability and fracture resistance, thereby becoming the decisive factor in microstructure optimization and service life prediction of aviation titanium alloy structural components. This paper proposes a fracture prediction method based on FEM that integrates experimentally characterized EBSD data with a modified fracture criterion to study the stress–strain evolution, deformation, and fracture behavior of TC17(α + β) and TC17(β) titanium alloys under tensile loading conditions. The model effectively reveals the influence of phase interfaces on mechanical properties and fracture behavior. The research results indicate that the simulated elastic modulus, yield strength, tensile strength, and elongation of TC17(α + β) titanium alloy are 92.34 GPa, 1030 MPa, 1119.7 MPa, and 3.2%, respectively, while those of TC17(β) are 91.58 GPa, 1031.8 MPa, 1175.5 MPa, and 3.15%, respectively. The deviation rates between simulated and experimentally measured (SEM in situ tensile test) mechanical properties are all within 3.5%, with the exception of elongation which exhibits a deviation below 8%. Stress and strain concentrations in TC17(α + β) titanium alloy primarily develop at interfaces between either equiaxed or lamellar α phase and the β matrix, whereas in TC17(β) alloy, they predominantly form at grain boundary α phase/β matrix interfaces (α phase at prior β-grain boundaries) or within β matrix regions adjacent to lamellar α phase termini. Crack initiation consistently occurs at α/β interfaces, specifically at equiaxed α phase interfaces in TC17(α + β) and grain boundary α phase interfaces in TC17(β), with subsequent propagation proceeding either along α phase interfaces or through α phase into the β matrix, where the basketweave structure demonstrates significantly greater crack propagation resistance compared to lamellar structures.

Graphical abstract