Coarse Columnar Grains Research Articles

Remelting of Aluminum Scrap Into Billets Using Direct Chill Casting

An as-cast aluminum billet with a diameter of 100 mm has been successfully prepared from aluminum scrap by using direct chill (DC) casting method. This study aims to investigate the microstructure and mechanical properties of such as-cast billets. Four locations along a cross-section of the as-cast billet radius were evaluated. The results show that the structures of the as-cast billet are a thin layer of coarse columnar grains at the solidified shell, feathery grains at the half radius of the billet, and coarse equiaxed grains at the billet center. The grain size tends to decrease from the center to the surface of the as-cast billet. The ultimate tensile strength (UTS) and the hardness values obtained from this research slightly increase from the center to the surface of the as-cast billet. The distribution of Mg, Fe, and Si elements over the cross-section of the as-cast billet is inhomogeneous. The segregation analysis shows that Si has negative segregation towards the surface, positive segregation at the middle, and negative segregation at the center of the as-cast billet. On the other hand, the Mg element is distributed uniformly in small quantities in the cross-section of the as-cast billet.

A new laser remelting strategy for direct energy deposition of 316L stainless steel

At present, components produced by Direct energy deposition (DED) still have many shortcomings, such as rough surfaces, many internal pores, and the formation of long columnar grains that will lead to anisotropy due to large temperature gradients. Laser remelting (LR) is an effective method to improve the top surface quality and densification of samples. In the present work, in the process of manufacturing 316L stainless steel samples with DED, an additional LR process without powder conveying is added after each deposition layer of the samples is deposited. The smoothness of the sample surface has been greatly improved, and the density of the samples has been increased to nearly fully dense. The number and size of pores inside the samples are significantly decreased. By changing laser power and spot size, the effect of the LR process with different energy densities on microstructure and mechanical properties was studied. After the LR process, the coarse and long columnar grains in samples are transformed into fine equiaxed grains and fine columnar grains. Experimental results show that the LR process with appropriate energy density can reduce the residual stress of the samples made by DED and significantly improve the tensile strength and elongation of the samples. LR with the same processing parameters as the deposition has the most obvious effect on refining the microstructure and improving tensile properties. However, the LR process with low energy density will increase the residual stress of the sample, resulting in poor mechanical properties.

In-situ alloying of NiTiNb ternary shape memory alloys via laser powder bed fusion using pre-alloyed NiTi and elemental Nb powders: Microstructure, phase transformation behavior and functional properties

Laser powder bed fusion (L-PBF) provides not only the advantage to make geometrically complex structures, but also the potential for in-situ alloying. In this work, (NiTi)100–xNbx (x = 1, 3, 5, 9 at%) ternary shape memory alloys were in-situ synthesized through L-PBF using a mixture of pre-alloyed near-equiatomic NiTi and elemental Nb powders. Low-Nb (1, 3 at%) alloys exhibit coarse columnar grains and high cracking tendency, while high-Nb (5, 9 at%) alloys show fine microstructure and low cracking susceptibility. Increasing Nb content leads to a transition from planar to cellular/dendritic growth, as a result of the increased constitutional supercooling (ΔTCS) and thermal undercooling (ΔTt) ahead of the solidification front. The L-PBF fabricated (NiTi)91Nb9 alloy shows comparable transformation characteristics to the conventional Ni47Ti44Nb9 alloy, with martensite start temperature (Ms) of 190 K and thermal hysteresis up to ca. 170 K after 20% pre-deformation. Achieving low Ms temperature with near-equiatomic Ni/Ti composition (i.e., Ni/Ti=1.024) is attributed to severe lattice distortion caused by Nb solution in the supersaturated matrix and the depletion of Ti to form the Ti-rich β-Nb phase, which resulted from the intrinsic rapid solidification associated with L-PBF. The in-situ alloyed (NiTi)100–xNbx alloys exhibit good mechanical and functional properties (total fracture strain >7%, and shape recovery rates >85%). This work may provide insights into in-situ alloying of NiTi-based ternary SMAs through L-PBF.

Cold-wire assisted arc direct-energy deposition of VC-strengthening 5A06 aluminum alloy: Microstructures and mechanical properties

In this study, vanadium carbide (VC) was initially introduced into the molten pool using the cold wire method to refine the deposit grains and enhance the mechanical properties of arc direct energy deposition (ADED) aluminum alloy. Next, the grain structure's evolutionary behaviors and the second phase in the VC-strengthening ER5A06 aluminum alloy deposits were investigated, and the grain refinement mechanism was determined. The findings demonstrated that the cubic Al10V phase was produced after introducing VC, and the grain structure in the middle stable region of the building wall was transformed from coarse columnar grains (with an average size of 42.3 μm) into equiaxed fine grains (with an average size of 16.4 μm). Both Al10V and VC were coherent to α-Al in terms of orientation: (020)α-Al//(444)Al10V, [101―]α-Al//[112―]Al10V, and (111)α-Al//(111)VC and [011]α-Al//[011]VC. Their interatomic and interplanar spacing misfits were lower than 5 %, facilitating the heterogeneous nucleation of α-Al during molten pool solidification. Moreover, under multiple thermal cycles of ADED, the pinning effect of VC and Al10V effectively restricted the grain growth, thus enabling the building wall to steadily maintain a uniform, equiaxed, and fine-grained structure. Due to grain refinement and homogenization, the horizontal and vertical ultimate tensile strengths of the straight wall were improved by 16.8 % and 50.2 % (351.6 and 348.1 MPa), respectively, thereby eliminating the mechanical anisotropy. This work can provide a theoretical foundation and a novel method for the fine microstructure regulation and reinforcement of ADED aluminum alloy components.

Fabrication of heterostructured Ti alloys with exceptional strength and ductility by direct laser deposition

Most metallic structural materials possess an intrinsic inverse relationship between strength and ductility. Heterostructured materials are expected to address this issue. Through composition regulation, TC4/TC4+2.5Ni layered heterostructures with exceptional strength and ductility were fabricated by direct laser deposition (DLD), exhibiting a significant increase in strength compared to that of TC4 while retaining excellent ductility. The mechanism of strength–ductility synergy was investigated under different alternating interlayer design conditions. The addition of nickel refined the microstructure of TC4, promoting the transformation of coarse columnar grains into nearly equiaxed grains. The DLD-fabricated TC4/TC4+2.5Ni layered heterostructure comprised alternating regions of columnar and near-equiaxed grains. By appropriately adjusting the thickness of alternating components (three to four DLD-deposited layers), a significant compositional and microstructural heterogeneity was achieved, resulting in a synergistic effect on strength and ductility in TC4-TC42.5Ni layered heterostructures. Moreover, strength–ductility synergy was achieved under the combined effect of hetero-deformation-induced stress, crack deflection near the component interface, and inhibition of strain localization by alternating soft and hard regions. This study provides a theoretical foundation and key evidence for designing DLD-deposited heterostructured titanium alloys with improved strength–ductility synergy, offering novel insights and contributions to improving the performance of titanium alloys.

Formation mechanisms and control strategies of metallurgical defects and microstructures during laser powder bed fusion of AlSi10Mg lattice structures

Lattice structures fabricated using laser powder bed fusion (LPBF) are pivotal for lightweight design. However, their small dimensions and intricate geometry intensify the likelihood of defect formation, such as lack of fusion (LOF), near-spherical pores, and microstructural coarsening. In this study, it was observed that the central region of lattice struts was especially susceptible to large-sized LOF in conjunction with the concave top surfaces due to frequent laser jumps. Furthermore, overheating during turnaround was identified as a contributor to excessive pores and surface bulging. Intriguingly, a unique layered melt mode emerged, characterized by coarse columnar grains exceeding 30 μm in size. A novel approach is proposed to reduce defects, refine grains, and enhance hardness during LPBF process, utilizing low laser power and a continuous scanning strategy. Using this manipulation strategy on typical lattice structures, porosity levels decreased by over 40 %. Ultimately, this research offers invaluable insights into refining printing conditions for lattice structures.

Effects of pulsed frequency on the microstructure characteristics and properties of Ti6Al4Vlaser melting deposition additive manufacturing parts

Laser melting deposition–produced Ti6Al4V additive manufacturingparts tend to manifest as coarse columnar grains. This paper optimises the laser pulse frequency to manage the microstructuralcharacteristics of Ti6Al4V parts and enhance their tensile properties and corrosion resistance. A fiber laser processing equipment with a laser power of 1200 W and a spot diameter of 2.0 mm was employed for all experiments, which provides pulsed lasers at 4, 40, 400, and 4000 Hz at a scanning speed of 8 mm/s and a duty cycle of 95 % for comparative research.The findings demonstrated that increasing the pulse frequency improved the deposition efficiency.An appropriate pulse frequency could promote the refinement and columnar-to-equiaxed transition (CET) of primary β grains.At 400 Hz, the Ti6Al4V-deposited parts yielded refined equiaxed grains.The average grain size in the middle of the sample was about 206.8 μm,and the microstructure mainly comprised fine α-laths in a lamellar structure, which yielded the best overall performance of the parts, with the ultimate tensile strength and elongation reaching 1083 MPa and 4.09 %, respectively.Therefore, improvingthe structural properties of partsby regulating the deposition process, which is conducive to the online regulation of the forming quality of laser deposition parts, is an effective and feasible approach.

Variational mode decomposition based self-adaptive denoising imaging method for ultrasonic array testing of coarse-grained titanium alloys processed by additive manufacturing

The coarse columnar grain structure in titanium alloys processed by additive manufacturing leads to strong grain noise in ultrasonic testing, which affects the accurate detection and quantification of its defects. In this paper, a self-adaptive denoising imaging method for ultrasonic array testing is proposed based on variational mode decomposition (VMD). The proposed method uses VMD to decompose complex ultrasonic signals in full matrix capture (FMC) data collected by a linear ultrasonic array transducer. According to the particle swarm optimization (PSO) method, VMD parameters for FMC methods of the total focusing method (TFM), the plane wave imaging (PWI), and the Hadamard spatial encoding are self-adaptively determined. The evaluation parameters are set to select the intrinsic mode function components by VMD to complete the denoising reconstruction and imaging of FMC data. An additive-manufactured titanium alloy specimen was used to verify the improvement of defect detection capability by PSO-VMD denoising method. For a defect at large thickness in the specimen, compared with the conventional TFM and PWI methods, VMD denoising method based on the Hadamard spatial encoding can improve the signal-to-noise ratio by 7.7 dB and 9.0 dB, and reduce the quantitative error by 74 % and 68 %.

Experimental investigations on the microstructural evolution and their influence on mechanical, tribological and corrosion performance of wire-arc additive manufactured SS316L structure

The study investigates the feasibility of emerging wire arc additive manufacturing technology to fabricate steel structures. The grain morphology and phase transformation of the WAAM-printed structure have been thoroughly examined and investigated their influence on the mechanical, tribological, and corrosion performance. The structure is characterized by fine equiaxed grains nearer to the cold substrate and coarse columnar grains along the upper regions. The average grain size in the top, middle, and bottom regions of the printed wall is 12.34 ± 5.81 µm, 10.27 ± 2.84 µm, and 4.33 ± 0.89 µm respectively. The higher temperature gradient in the bottom regions led to the ferrite-austenite solidification mode that switched toward the primary austenite solidification mode in the upper layers. The printed parts witness superior mechanical properties with an improved micro-hardness and tensile strength however reduced ductility compared to the conventionally produced steel. The longitudinal direction of the printed parts experienced slightly higher hardness than the transverse. The tribological performance in different regions is investigated under different loading conditions and discovered an improvement in the wear-resistant properties of the fabricated part to its wrought counterpart even at high load conditions. Moreover, comparative corrosion resistance properties of the WAAM and wrought steel were detected with a slightly higher corrosion rate along the upper region in a moderately saline environment with flowing and stagnant conditions. The study detects the dependence of the characteristics properties on the grain morphology and existing phases in different regions of the arc additive-manufactured steel wall.

Study on the Microstructure and Mechanical Properties of Ultrasonic-Assisted TIG Welded 441 Ferritic Stainless Steel Joints

A self-designed ultrasonic-assisted welding platform was built to improve the poor microstructure and properties of conventional TIG welded ferritic stainless steel. The ultrasonic vibration was transmitted to the weld pool through the base metal in the manner of point–surface contact in the optimal position after calculation. The results show that the coarse columnar grains in the welded joint can be transformed into very fine equiaxed grains under ultrasonic vibration, especially the coarse columnar grains near the fusion line where cliff-like refinement occurs. The maximum grain size in the weld seam is reduced from 420 μm to 260 μm, and the average size is reduced by 60%. At the same time, the grain orientation tends to be harmonized. The microhardness of the welded joint is greatly improved on the whole, and the softening of the heat-affected zone caused by grain coarsening is effectively inhibited. Compared with the welded joints without ultrasonic assistance, the tensile strength and yield strength can be increased by 61 MPa and 47 MPa, respectively, under 130 W ultrasonic vibration. By strengthening the weak part of the welded joint, the weldability and toughness reserve of 441 ferritic stainless steel can be significantly improved.

Single track versus bulk samples: Understanding the grain refinement in inoculated ferritic stainless steels manufactured by powder bed fusion-laser beam

One generic challenge in powder bed fusion - laser beam (PBF-LB) is the formation of epitaxially grown columnar grains, which lead to the undesirable anisotropy of mechanical properties. This anisotropy could be rectified by ex-situ or in-situ inoculation in some particular alloy systems. Understanding the grain refinement mechanism caused by in-situ inoculation is, however, complicated by remelting caused by the overlapping between neighboring scan tracks, when printing bulk samples using multiple tracks. Here in this work, a series of single tracks using ferritic stainless steels feedstock powder with and without pre-alloyed inoculant-forming elements, were printed at different scanning speeds to gain refreshed understanding on the mechanism of the observed grain refinement. Interestingly, the grain refinement in single tracks and bulk samples printed from the powder with and without inoculant-forming elements showed an opposite tendency. When using the powder without inoculant-forming elements, the single tracks showed large columnar grains, while the bulk samples showed even larger grain sizes; when using the powder with pre-alloyed inoculant-forming elements, fine equiaxed grains are found at the centers of the melt pools, surrounded by slightly coarser columnar grains at melt pool boundaries, in both single tracks and bulk samples. Noticeably, the mean grain sizes in the bulk samples are however smaller compared to those for single tracks because of remelting. Our work provides new insights on the grain refinement via in-situ inoculation during the PBF-LB process and highlights the importance of studying single tracks to better understand the melting and solidification behavior.

Unusually high room and elevated-temperature tensile properties observed in direct aged wire-arc directed energy deposited Inconel 718

Wire-arc directed energy deposition (DED) processed Inconel (IN) 718 is known to have coarse columnar grains, strong texture, and significant chemical and microstructural inhomogeneity in the as-fabricated condition. Homogenization treatment is commonly used prior to aging to eliminate the inhomogeneity and detrimental precipitation for better mechanical properties. In this study, however, direct aging (DA) at 700 °C without homogenization has resulted in room-temperature yield strength, ultimate tensile strength (UTS), and elongation that are comparable to wrought condition and among the highest reported properties for wire-arc DED IN718. The DA samples at between 650 and 750 °C aging also demonstrates remarkable ductility when deformed at elevated temperatures. In addition, when aged below 750 °C the DA IN718 possesses significantly higher UTS compared to those with homogenization treatment. These superior mechanical properties are highly likely due to the non-uniform and hierarchical precipitation consisting of disk-shaped γ″ in diameter from a few to tens of nm in the dendritic core area and micron-sized Laves phase and carbides in the inter-dendritic region.

Electron beam welding of L12-nanoparticle-strengthened strong and ductile medium-entropy alloys for cryogenic applications

The weldability, microstructures, and mechanical properties of two L12-nanoparticle-strengthened medium-entropy alloys (MEAs) Ni43.4Co25.3Cr25.3Al3Ti3 and Ni42.4Co24.3Cr24.3Al3Ti3V3 (at.%) are explored after electron beam welding (EBW). Strong yet ductile defect-free joints were produced with coarse columnar grains (118–245 μm) in the fusion zones, which were larger than the equiaxed grains in the heat-affected zones (15.6–22.3 μm) and in the base materials (4.6–5.6 μm). Both EBWed MEAs showed high yield strengths (838–858 MPa), high ultimate tensile strengths (1416–1420 MPa), and good fracture strains of 20–21 % at 77 K, which are 66∼83 %, 84–89 %, and 57–81 %, respectively, of those of the respective thermo-mechanically treated (TMT) MEAs. The V-doping improved the cryogenic mechanical properties of the TMT MEA while not influencing those of the EBWed MEA. High back-stress hardening contributes to over 50 % of the cryogenic strength. Both EBWed MEAs exhibited abundant dislocation networks, stacking faults, and nanoscale deformation twins after fracture, producing a high strain hardening rate and good ductility.

Significant reduction of grain size and texture intensity in laser powder bed fusion fabricated nickel-based superalloy by increasing constitutional supercooling

Coarse columnar grains are always present in nickel-based superalloys fabricated by laser powder bed fusion (LPBF), which not only causes anisotropy in mechanical properties, but also increases the hot cracking susceptibility of the alloys. Generally, the addition of nucleating agents is a common consideration for grain refinement. However, the intrinsic ultra-high thermal gradient and cooling rate of the LPBF process result in significant differences in grain nucleation and growth compared to conventional casting. The ultra-high thermal gradient of the LPBF process severely inhibits constitutional supercooling, which significantly reduces the heterogeneous nucleation efficiency of nickel-based superalloys. In this work, we introduced Zr into Haynes 230 alloy to improve constitutional supercooling of the LPBF molten pool during solidification and investigated the individual/synergistic effects of nucleating agent (TiC particles) and solute (Zr atoms) addition on the grain refinement of Haynes 230 alloy. It was found that the columnar grain size and texture intensity of LPBF fabricated Haynes 230 alloys were dramatically decreased with Zr and TiC co-addition, which obviously improved the mechanical properties as well as weakened its anisotropy. Our work revealed that inhibition of cell epitaxial growth and promotion of cell nucleation are necessary conditions to refine the grain size of LPBF fabricated nickel-based superalloys. Solutes with high growth restriction factor (Q value), such as Zr in our work, can rapidly generate constitutional supercooling, thereby obviously improving the heterogeneous nucleation efficiency of nucleating agents in nickel-based superalloy during the LPBF process.

Anisotropy in flow behaviour of directionally solidified Ni-based superalloy under compression at an elevated temperature

Directionally solidified (DS) superalloys consist of coarse columnar grains with <001> preferred orientation parallel to the maximum stress axis; but, grain orientations in the transverse direction are not controlled. However, during service, substantial loading could occur in the transverse direction as well, leading to early intergranular failure of components such as DS turbine blades. The present study investigates the effect of crystallographic orientation as well as specimen orientation (transverse and longitudinal with respect to grain growth direction) on the mechanical response of DS Ni-based superalloy in compression. Compression tests were performed at 700 ºC on transverse (with predominantly <101> or <001> oriented grains) and longitudinal (with <001> oriented grain) samples. Though there were negligible changes in yield stress, variations in hardening behaviour and ductility were observed in all the tested samples. Unlike transverse samples, longitudinal samples showed significant strain hardening with no failure even up to 0.3 true strain. Deformation mechanisms that led to these differences are identified using advance characterization techniques. γ' shearing with antiphase boundary formation was observed in the sample containing <101> grains, whereas γ' shearing with the formation of superlattice intrinsic stacking faults occurred in the sample having <001> grains. In addition, substantial lattice rotation and deformation twinning also contribute to strain hardening, especially in longitudinal samples. The effect of orientation is explained in terms of effective stacking fault energy. The study suggests that grains with <001> orientation undergo significant strain hardening and thereby accommodate large strain as compared to <101> oriented grains in DS alloys.

Revealing the effect of Si content on the microstructure and properties of Al–Si alloy by experiments and phase-field simulation

The grain size of aluminum alloy is closely related to solute content and solidification conditions. This study investigated the influence of Si content on the solidification microstructure and properties of the Al–Si binary alloy by experiments and phase field simulation. The experimental results indicated that the microstructure of Al–Si alloy changes from coarse columnar grains to uniformly distributed equiaxed grains as Si content increases from 0 to 7 wt%, and the average grain size of Al–2Si is the smallest (2.2 mm). Meanwhile, the tensile strength of Al–Si alloys increases from 56.9 MPa to 111 MPa with increasing Si content, whereas the ductility decreases from 30% to 2.5%. Moreover, high casting temperature will produce coarse columnar crystals, low casting temperature forms equiaxed crystals, the optimal casting temperature in this study is 30 °C above the liquidus. Phase field simulations reveal that the evolution of Al–Si microstructures is governed by two dimensionless parameters: the initial temperature (T0), related to casting temperature and solidification interval, and the latent heat (K1), connected to latent heat, specific heat, and solidification interval. For a certain alloy composition (Al–2Si), the grain size exhibits a non-monotonic trend, decreasing initially and then increasing as T0 increases, with an optimal T0 value of 1.42. When the Si content varies between 2 and 7 wt%, the average grain sizes decrease as K1 increases, with the maximum K1 value observed at 1.38 for Al–2Si.

Characterization of crack-free AA-7075 fabricated by laser powder bed fusion with addition of Zr50.7Cu28Al12.3Ni9 metallic glass

The inclusion of 2 wt% Zr50.7Cu28Al12.3Ni9 metallic glass (MG) powders successfully eliminated the hot cracks in AA-7075 specimens fabricated using laser powder bed fusion (LPBF). The microstructure analysis revealed a significant enhancement in grain refinement within the AA-7075/MG specimen as a result of the formation of Al3Zr precipitates. The average grain size reduced from 9.26 μm to 1.6 μm, and the previously coarser columnar grains transformed into finer equiaxed grains with random orientation. Moreover, the AA-7075/MG specimen demonstrated a noteworthy microhardness exceeding 160 HV. With an elongation of about 7.2%, the highest ultimate tensile stress and yield strength are 488.7 MPa and 460.8 MPa, respectively.

Complete fine-equiaxed β-columnar grains in laser direct energy deposition of Ti–6Al–4V parts

Coarse β-columnar grains are often present in Ti–6Al–4V laser-additive-manufactured samples, resulting in anisotropic and inferior fatigue performance under dynamic loading. Fine-equiaxed grains (FEGs) with a mean grain size of approximately 139 μm were successfully obtained by a novel deposition strategy through coordinated regulation of direct energy deposition technological parameters. Microstructures were transformed from α′ martensite to α'' martensite. As a result, the comprehensive performance was significantly improved. Without the use of an argon atmosphere glovebox and post heat treatment, the tensile strength and elongation in the horizontal direction of the FEGs were 1091 MPa and 4.09%, respectively. The corrosion resistance was 11.71-fold higher than that of the coarse columnar grains (CCGs). Improving the microstructure and performance by optimizing pulsed laser parameters is simple, effective, and conducive to online regulation of the quality of laser additive samples.

Anisotropic response in mechanical and corrosion performances of UNS S31803 duplex stainless steel fabricated by laser powder bed fusion

Mechanical and corrosion behaviors perpendicular to build direction (XOY) and along build direction (XOZ) of UNS S31803 duplex stainless steel (DSS) fabricated by laser powder bed fusion (LPBF) were investigated. With the post-annealing, the steel exhibited a ferrite-austenite microstructure. For XOY plane, austenite displayed a primarily <101> texture while ferrite kept <001> preferred orientation, and mainly held a Nishiyama-Wassermann orientation relationship. However, for XOZ plane, austenite showed a mixed texture. The average size of ferrite grains was larger for XOZ plane than XOY. The austenite in XOY plane was mostly island morphology grains, while in XOZ plane, there were a large number of coarse columnar grains. A higher geometrically necessary dislocation density and proportion of low-angle grain boundaries on XOY plane were observed. The yield strength and ultimate tensile strength values perpendicular to build direction were higher than those along build direction. While the total elongation perpendicular to build direction was lower. Moreover, the XOY plane shows slightly better corrosion resistance than the XOZ.

The hot deformation behavior and dynamic microstructure evolution of additive manufactured Ti6Al4V with different hydrogen addition

During the laser melting deposition (LMD) additive manufacturing process, titanium alloys undergo rapid solidification, which induce grain growth into coarse columnar grains, resulting in lower mechanical properties of the material than conventional forgings. This study proposes the incorporation of hydrogen into titanium alloys to refine columnar grains, reduce deformation resistance, and improve machinability. In this work, the hot deformation behavior of hydrogenated Ti6Al4V alloy was analyzed via high-temperature compression experiment. The experimental results revealed the nucleated grains generated by the intense deformation and the twins brought by the hydrogen element led to massive dynamic recrystallizations, which effectively improved the hot workability. When the alloys are deformed above phase transition temperature, the flow stress is positive related with H content. Meanwhile, when the alloys are deformed below the phase transition temperature, the flow stress initially experiences a decrease with an increase in hydrogen content. Adding only 0.27 wt% H can reduce the flow stress by 34.4%–54%, but when the H content continues to increase, the flow stress still increases subsequently. Moreover, when the strain rate is constant, the flow stress of Ti6Al4V alloy can decrease by about 80% with an increase in deformation temperature from 820 °C to 940 °C. When the deformation temperature is constant, the flow stress of Ti6Al4V alloy with different hydrogen contents can decrease by around 65% as the strain rate reduces from 10s−1 to 0.01 s−1.