Phase transformation mechanisms, microstructural characteristics and mechanical performances of an additively manufactured Ti-6Al-4V alloy under dual-stage heat treatment

Su, Jinlong; Jiang, Fulin; Li, Junjie; Tan, Chaolin; Zhao, Xu; Xie, Haiming; Liu, Jin; Tang, Jie; Fu, Dingfa; Zhang, Hui; Teng, Jie

doi:10.1016/j.matdes.2022.111240

Cited by 25 publications

(7 citation statements)

References 52 publications

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“…Some of the β phase was generated during heating, and most of it was converted into the α phase again during subsequent cooling to room temperature, with a small fraction of it eventually remaining, while the α phase increased in the heating and cooling process of local PWHT, and its volume fraction reached about 0.97 after cooling to room temperature, which will affect the mechanical properties of welded joints. The discovery in this simulation analysis that the decomposition of α'→α + β occurred during local PWHT also appeared in the results obtained by the researchers through experiments [32][33][34].…”

Section: Metallurgical Analysissupporting

confidence: 75%

Thermo-Mechanical Study of TIG Welding of Ti-6Al-4V for Residual Stresses Considering Solid State Phase Transformation

Liu

Zheng

et al. 2023

Metals

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To overcome the detrimental effect of residual stress in welded joints, which affects the overall performance of the welded structure, this paper studies the magnitude and distribution of residual stress after welding and local post-weld heat treatment (PWHT). The coupled thermo-metallurgical-mechanical model for welding 6 mm thick Ti-6Al-4V (TC4) titanium alloy plates was established, the evolution of the SSPT and its effect on the residual stress were quantitatively analyzed, and a parametric analysis of local PWHT was performed. The results demonstrated that there was good agreement between the numerical results and the experimental data. Due to the cooling rate reaching 327 °C/s, the volume fraction of α、 in the fusion zone (FZ) reached 0.218 after welding and decreased by 90.83% after PWHT when the heating temperature was 700 °C. The peak value of the longitudinal residual stress can reach 686.4 MPa after welding with SSPT, which was 11.38% lower than that without SSPT, and it decreased by 65.6% after PWHT when the heating temperature was 900 °C. The research results demonstrate that SSPT has a significant effect on residual stress, and PWHT can obviously reduce the residual stress, which provides a certain reference for welding TC4 titanium alloy plates.

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Section: Metallurgical Analysissupporting

confidence: 75%

Thermo-Mechanical Study of TIG Welding of Ti-6Al-4V for Residual Stresses Considering Solid State Phase Transformation

Liu

Zheng

et al. 2023

Metals

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“…This region, known as the particle deformation zone, is usually the preferred nucleation site for DRX [27] . The dislocation density ρ in the hot‐forged specimen is calculated as 3.98 × 10 15 m −2 , using the modified Williamson–Hall method [28] . The calculation method of dislocation density is summarized in Supporting Information : Appendix D.…”

Section: Discussionmentioning

confidence: 99%

High throughput construction for the deformation mechanism diagram and dynamic recrystallization of a bimodal‐sized particle‐reinforced Ti‐2.5Zr‐2Al‐1(Si,C) titanium alloy

An,

Zhou,

Wei

et al. 2023

Materials Genome Engineering Advances

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An in situ autogenous particle‐reinforced Ti‐2.5Zr‐2Al‐1(Si,C) titanium alloy is prepared by vacuum induction melting. The wide range of an effective strain between 0.2 and 1.2 and the corresponding microstructure are obtained by the double‐cone high‐throughput compression test and finite element simulation. The deformation mechanism diagram with strains of 0.2–1.2 and strain rates of 0.7–1.5 s−1 at 900°C is constructed. When the strain rate is 1.3 s−1, dynamic recovery occurs in the small strain range (<0.377), dynamic recrystallization (DRX) occurs in the medium strain range (0.377–1.182), and deformation instability occurs in the large strain range (>1.182), resulting in the deformation bands. High‐angle annular dark field and high‐resolution transmission electron microscopy are used to determine the existence of bimodal particle distribution, namely micron‐scale TiC particles and nano‐scale Ti5Si3 and (Zr, Si) particles. The average radius of the (Zr, Si) nanoparticles measured by small angle neutron scattering is 19.3 nm, and the volume fraction is 0.35%. DRX grains with an average size of 0.49 μm are obtained at 900°C, strain rate of 1.3 s−1, and strain of about 0.6. Micron‐scale particles stimulated DRX nucleation, while nanoscale particles hindered the growth of new grains, resulting in grain refinement.

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“…Post heat treatment (post-HT) is generally needed for the LPBF-fabricated Ti alloys to decompose metastable phases (e.g., martensitic α ); alleviate residual stress; and improve ductility, fracture toughness, and fatigue performance [9,10]. As the work-horse Ti alloy, numerous works have been carried out to investigate the effects of post-HTs on the microstructure, residual stress, and mechanical properties of the LPBF-built Ti-6Al-4V alloy [11,12].…”

Section: Introductionmentioning

confidence: 99%

Phase Transformation Behaviors and Dislocation Evolutions of an Additively Manufactured Ti-6Al-4V Alloy under Annealing Treatment

Ji¹,

Xie

et al. 2023

Metals

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Post annealing treatment is generally needed for additively manufactured titanium alloy to decompose metastable phases, alleviate residual stress, and improve ductility. In this work, in-situ electrical resistivity and line profile analysis of X-ray diffraction were utilized for monitoring phase transformation behaviors and dislocation evolutions of a laser powder bed fusion-built Ti-6Al-4V alloy under post annealing treatment. Besides, hardness and tensile tests were adopted for revealing the effects of phase transformation and dislocation evolutions on the mechanical properties. The results indicated that post annealing treatment decomposed martensitic α′ into lamellar α + β and eliminated dislocations efficiently. The martensite decomposition rate increased with the annealing temperature. Annealing at 700 °C for 4 h eliminated 98% of the dislocations, and further annealing has only a limited influence on the dislocation density. Annealing at 700 °C for 16 h is beneficial for achieving a high ductility of 10.3% owing to the favorable equilibrium lamellar α + β microstructure. These findings provide valuable insights for optimizing post annealing treatment procedures to enhance the mechanical properties of additively manufactured Ti-6Al-4V alloys.

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Phase transformation mechanisms, microstructural characteristics and mechanical performances of an additively manufactured Ti-6Al-4V alloy under dual-stage heat treatment

Cited by 25 publications

References 52 publications

Thermo-Mechanical Study of TIG Welding of Ti-6Al-4V for Residual Stresses Considering Solid State Phase Transformation

Thermo-Mechanical Study of TIG Welding of Ti-6Al-4V for Residual Stresses Considering Solid State Phase Transformation

High throughput construction for the deformation mechanism diagram and dynamic recrystallization of a bimodal‐sized particle‐reinforced Ti‐2.5Zr‐2Al‐1(Si,C) titanium alloy

Phase Transformation Behaviors and Dislocation Evolutions of an Additively Manufactured Ti-6Al-4V Alloy under Annealing Treatment

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