Columnar Prior-β Grains Research Articles

Hybrid Fabrication of Cold Metal Transfer Additive Manufacturing and Laser Metal Deposition for Ti6Al4V: The Microstructure and Dynamic/Static Mechanical Properties.

The titanium alloy components utilized in the aviation field are typically large in size and possess complex structures. By utilizing multiple additive manufacturing processes, the precision and efficiency requirements of production can be met. We investigated the hybrid additive manufacturing of Ti-6Al-4V using a combination of cold metal transfer additive manufacturing (CMTAM) and laser metal deposition (LMD), as well as the feasibility of using the CMT-LMD hybrid additive manufacturing process for fabricating Ti-6Al-4V components. Microstructural examinations, tensile testing coupled with digital image correlation and dynamic compressive experiments (by the split Hopkinson pressure bar (SHPB) system) were employed to assess the parts. The results indicate that the interface of the LMD and CMTAM zone formed a compact metallurgical bonding. In the CMTAM and LMD zone, the prior-β grains exhibit epitaxial growth, forming columnar prior-β grains. Due to laser remelting, the CMT-LMD hybrid additive zone experiences grain refinement, resulting in equiaxed prior-β grains at the interface with an average grain size smaller than that of the CMTAM and LMD regions. The microstructures reveal significant differences in grain orientation and morphology among the zones, with distinct textures forming in each zone. In the CMT-LMD hybrid zone, due to interfacial strengthening, strain concentration occurs in the arc additive zone during tensile testing, leading to fracture on the CMTAM zone. Under high-strain-rate dynamic impact conditions, the LMD region exhibits ductile fracture, while the CMTAM zone demonstrates brittle fracture. The hybrid zone combines ductile and brittle fracture modes, and the CMT-LMD hybrid material exhibits superior dynamic impact performance compared to the single deposition zone.

Effect of gradient decrease heat-input combined with inter-layer cooling on microstructure and mechanical properties of WAAM-Ti-6Al-2Zr-1Mo-1V alloy

In conventional Wire Arc Additive Manufacturing (WAAM), coarse epitaxial growth columnar prior-β grains always lead to a strong texture and poor mechanical properties. To solve this problem, a new deposition strategy combining gradient decrease heat-input and inter-layer cooling was proposed in this study. This deposition strategy significantly increased the cooling rate and reduced the inter-layer temperature, which interrupted the epitaxial growth of columnar grains and formed a fine columnar-equiaxed mixed grain morphology. Due to the decrease of thermal cycles, the layer band structure tended to be evenly distributed and a small amount of martensite α' remained at the bottom of layer band structure. In addition, the generation of α colony and the transformation of β phases were also inhibited by the high cooling rate. In the meantime, finer basketweave structure composed of the short rod-like α laths was formed in the mixed grains. Compared with the traditional deposition strategy, this method can obtain a WAAM-Ti-6Al-2Zr-1Mo-1V alloy with microhardness of 376.23HV0.2, ultimate tensile strength of 1014.8 MPa and elongation of 4.97%.

Effect of processing parameters on the defects, microstructure, and property evaluation of Ti-6Al-4V titanium alloy processed by laser powder bed fusion

In this study, we designed the processing windows for laser powder bed fusion (LPBF) of Ti-6Al-4V (Ti-64) alloy by using central composite design and made a detailed investigation into the influence of processing parameters on the defects. The purpose is to investigate the effect of defects on mechanical properties. It was found that insufficient energy density could lead to the formation of lack of fusion (LOF) defects and produce non-melted powders on the surface, while excessive energy density could lead to cracks that were detrimental to mechanical performance. In addition, the microstructural evaluation found that relatively low energy density could lead to shorter columnar prior-β grains, while prior-β grains in the sample processed by the high energy density extended almost the entire height of the cross-section, which could lead to the strong mechanical property anisotropy. The prior β grains are formed by heterogeneous nucleation on the partially melted material powder. As the energy input increases, all the powder powders in the molten pool can be melted so that these particles do not act as nucleation sites and the prior β grain can grow through more layers without forming new grains being able to nucleate. The prior β-grain in as-built Ti-64 samples consisted of acicular α’ martensite with myriads of lattice distortions, as a precursor to a phase transition, which lead to strong tensile strength and poor ductility. Annealing heat treatment promoted the improvement of the ductile performance of LPBF Ti-64. Overall, this study provides comprehensive views on the effects of processing parameters (laser power, scanning speed, and hatch distance) on the internal (pores and LOF) and external (unmelted powder, sintering neck, and crack), defects, microstructure, and tensile property evaluation of LPBF Ti-64, which offer insights for the development of additive manufactured titanium alloys with excellent mechanical property.

Grain refinement and anisotropy improvement of arc-directed energy deposited Ti–6Al–4V with oscillating laser

Ti–6Al–4V parts fabricated by wire plus arc additive manufacturing (WAAM) usually exhibit columnar grain shapes and serious anisotropy in mechanical properties. This study aims to solve these issues by proposing a laser-assisted WAAM technique in which a vertically oscillating laser beam acts on the molten pool in WAAM. The influences of oscillation laser power on the microstructure and mechanical properties of Ti–6Al–4V parts built in WAAM are revealed and discussed. The oscillation laser can refine prior-β grains in WAAM. As the laser power increases, the depths of laser fusion lines in deposited layers increase, the size of prior-β grains decreases first and then increases, and both the microhardness and ultimate tensile strength (UTS) increase first and then decrease. At a laser power of 1600 W, the columnar prior-β grains are completely transformed into equiaxed shapes. The UTS values in the vertical and horizontal directions reach 1322 and 1309 MPa, respectively, respectively 30.5% and 15.7% higher than those of the WAAM sample. Meanwhile, the indices of plane anisotropy of UTS and elongation decrease by 90.6% and 76.4%, respectively.

Insights into the microstructural design of high-performance Ti alloys for laser powder bed fusion by tailoring columnar prior-β grains and α-Ti morphology

A high-performance Ti-Ni-B alloy with good tensile properties and reduced mechanical anisotropy was developed by promoting the columnar to equiaxed transition (CET) of prior-β grains and modifying α-laths to equiaxed grains. Both Ni and B contributed to the refinement of columnar prior-β grains during the L→β phase transformation by generating constitutional undercooling. Compared with Ni, B had a superior capability of generating constitutional undercooling, which not only replaced a significant amount of Ni with a minor addition to reduce the formation of brittle eutectoid, but also reacted with Ti to form TiB to promote heterogeneous nucleation of α-Ti grains during the β→α phase transformation. Together with the restricted growth of α-laths induced by the refinement of prior-β grains, a fully equiaxed α-Ti structure was obtained. The competition between the negative effect of brittle eutectoid and the positive role of α-lath to equiaxed grain transition on the ductility of as-printed Ti-Ni-B alloys was fundamentally governed by the morphology of eutectoid and technically dependent on the Ni-B content. When the addition was 1.2Ni-0.06B (wt.%) or less, the positive effect of α-lath on equiaxed grain transition can effectively mitigate the issue of reduced ductility caused by brittle eutectoid. In contrast, at 1.8Ni-0.09B or greater, the negative effect of eutectoid dominated. New insights into microstructural design obtained through the aforementioned approach were presented and discussed.

Effect of microstructure evolution on tensile properties of arc wire directed energy deposited Ti-6.5Al-3.5Mo-1.5Zr-0.3Si titanium alloy

In this study, the static globularization and static coarsening behavior of arc wire directed energy deposited (AW-DEDed) Ti-6.5Al-3.5Mo-1.5Zr-0.3Si (TC11) alloy and their affected on tensile properties were studied. The as-deposited sample and the 550-AC (550 °C/4h/air cooling) sample showed columnar prior-β grains, while the microstructure showed the continuous αGB grew up through the colony microstructure and the basket-weave microstructure. The driving force in the α/β interface was enough for static globularization and static coarsening, which formed crack-like primary α (crab-like αP), αG (globularized α), and the αs (secondary α) during 970-AA (970 °C/2h/air cooling+550 °C/4h/air cooling) or 990-AA (990 °C/2h/air cooling+550 °C/4h/air cooling). The microstructure evolution and formation mechanism of the crab-like αP, the αG, and the αs were discussed. The formation of the αG was mainly via grain boundary splitting, and the formation of the crab-like αP was mainly via terminal migration with different interchanged interfaces. The ultrafine lamellae α nucleated with the sympathetic mechanism grew until lost burgers orientation relationships with adjacent grain boundaries and formed αS. The 550-AC sample showed the highest yield strength (YS, 905 MPa) and the highest anisotropic ductility (ΔEL, 7.9) than those in the 970-AA sample and the 990-AA ample. It was because the crab-like αP, the αG, and the αs decreased the fracture resistance in the 970-AA sample and the 990-AA sample.

Laser powder bed fusion (LPBF) of commercially pure titanium and alloy development for the LPBF process.

Laser powder bed fusion (LPBF) of titanium or titanium alloys allows fabrication of geometrically more complex and, possibly, individualized implants or osteosynthesis products and could thus improve the outcome of medical treatments considerably. However, insufficient LPBF process parameters can result in substantial porosity, decreasing mechanical properties and requiring post-treatment. Furthermore, texturized parts with anisotropic properties are usually obtained after LPBF processing, limiting their usage in medical applications. The present study addresses both: first, a design of experiments is used in order to establish a set of optimized process parameters and a process window for LPBF printing of small commercially pure (CP) titanium parts with minimized volume porosity. Afterward, the first results on the development of a biocompatible titanium alloy designed for LPBF processing of medical implants with improved solidification and more isotropic properties are presented on the basis of conventionally melted alloys. This development was performed on the basis of Ti-0.44O-0.5Fe-0.08C-0.4Si-0.1Au, a near-α alloy presented by the authors for medical applications and conventional manufacturing, with yttrium and boron additions as additional growth restriction solutes. In terms of LPBF processing of CP titanium grade 1 powder, a high relative density of approximately 99.9% was obtained in the as-printed state of the volume of a small cubical sample by using optimized laser power, scanning speed, and hatch distance in combination with a rotating scanning pattern. Moreover, tensile specimens processed with these volume settings and tested in the as-printed milled state exhibited a high average yield and ultimate tensile strength of approximately 663 and 747N/mm2, respectively, combined with a high average ductility of approximately 24%. X-ray diffraction results suggest anisotropic mechanical properties, which are, however, less pronounced in terms of the tested specimens. Regarding alloy development, the results show that yttrium additions lead to a considerable microstructure refinement but have to be limited due to the occurrence of a large amount of precipitations and a supposed higher propensity for the formation of long columnar prior β-grains. However, phase/texture and microstructure analyses indicate that Ti-0.44O-0.5Fe-0.08C-0.4Si-0.1Au-0.1B-0.1Y is a promising candidate to achieve lower anisotropy during LPBF processing, but further investigations on LPBF printing and Y2O3 formation are necessary.

Electron beam additively manufactured Ti–1Al–8V–5Fe alloy: In-situ precipitation hardening, tensile properties and fracture characteristics

Ti–1Al–8V–5Fe alloy was fabricated using electron beam powder bed fusion. No Fe-stabilized β-flecks were observed. In-situ precipitation hardening occurred in columnar prior-β grains. Nanoscale α-lath precipitates exhibited noticeable deformation while microscale α-laths became a major source of microcracks, which should be avoided. The as-fabricated Ti–1Al–8V–5Fe alloy showed significant tensile properties.

Toward developing Ti alloys with high fatigue crack growth resistance by additive manufacturing

Fatigue crack growth behaviors were investigated by three-point bending tests for TA19 alloy fabricated by laser metal deposition and four kinds of heat-treated samples. The crack growth resistance of the TA19 samples in the near-threshold regime and Paris regime was evaluated through the experimental characterization and theoretical analysis of the interaction between fatigue crack and α/β phase interface, columnar prior-β grain boundary and colony boundary. The results show that in the near-threshold regime, the fatigue crack propagation threshold and resistance increase with the increase of widths of lamellar αp phases and colonies, and the decrease of the number of α laths with an angle (φ) relative to the applied stress direction ranging from 75° to 90°. In the Paris regime, the fatigue cracking path can be deflected at colony boundaries or columnar prior-β grain boundaries. The larger the deflection angle, the more tortuous the cracking path and the lower the fatigue crack growth rate. The angle (γ) of the columnar prior-β grain growth direction relative to the build direction affects not only φ of different α variants, but also the fatigue cracking path deflection angle (θij) at columnar prior-β grain boundaries. An optimal combination of γ = 0°-15°-0°-15° for several adjacent columnar prior-β grains is derived from the theoretical analysis, and that can effectively avoid φ being in the range from 75° to 90° and make θij as large as possible. Such findings provide a guide for the selection of scanning strategies and process parameters to additively manufacture Ti alloys with high fatigue damage tolerance.

Reducing the anisotropy of the mechanical properties of directed energy deposited Ti6Al4V alloy with inter-layer ultrasonic impact peening and heat treatment

The microstructure and mechanical properties of directed energy deposited Ti6Al4V alloy upon inter-layer ultrasonic impact peening and heat treatment including thermal cycling and solution plus aging were studied. The results show that the anisotropy of the mechanical properties can be reduced by breaking columnar prior-β grains with inter-layer ultrasonic impact peening and spheroidizing primary α phases with heat treatment.

Laser powder bed fusion produced Ti-6Al-4V: Influence of high-energy process parameters on in-situ martensite decomposition and prior beta grain texture

Since Ti-6Al-4V components fabricated by laser powder bed fusion achieve an undesired martensitic microstructure (α'), high residual stresses and columnar prior-β grains, post-process heat treating has become an essential operation to improve these properties. However, post-process heat treating could be considered an undesirable additional step. Thus, this study investigated the viability of in-situ heating by experimentally establishing the effect of in-situ heating on part properties. This was accomplished by incrementally increasing the laser-induced energy density (Ev) above the machine-default Ev while maintaining high part density> 99%. Microstructural changes were monitored using optical and scanning electron microscopy and quantified using X-ray and electron-backscatter diffraction analysis. The study found a decrease in α grain size with an increase in Ev, a full α' decomposition at an Ev of 167 J/mm3 and indications of prior-β grain columnar-to-equiaxed transition at higher Ev. Graded properties along the sample height, and an increase in oxygen and nitrogen pick-up was measured at high Ev, causing a decrease in material ductility. A discussion of the thermodynamics of the process parameters demonstrated the mechanisms by which a reduced laser hatch distance controls powder bed fusion texture. Process variables of interaction time and exposure rate are proposed to better quantify the interactions between process parameters and thermodynamics.

Coaxial laser metal wire deposition of Ti6Al4V alloy: process, microstructure and mechanical properties

Wire-based additive manufacturing (AM) shows a promising prospect in fabricating large-scale titanium aerospace components at a high deposition rate and low cost. The currently used wire-based AM processes commonly utilize a lateral feeding method with an acute angle to form a deposit, which reduces the flexibility and increases the difficulty of control in making complex components. In this work, a novel coaxial laser metal wire deposition (LMWD) process was used to fabricate the most widely used titanium alloy, Ti6Al4V. The coaxial wire feeding was achieved by a coaxial laser head through a vertically fed wire surrounded by an annular shape beam at focal plane. The surface quality, microstructure and mechanical properties of the deposited Ti6Al4V were examined. To show the characteristic of the coaxial LMWD process, conventional lateral LMWD was also conducted for comparison. The deposited Ti6Al4V wall showed a high surface quality and a microstructure with a mix of equiaxed β grains and columnar prior-β grains rather than coarse prior-β grains. The refined microstructure resulted in a low anisotropy in mechanical properties. The mechanism of the equiaxed β grains formation was also discussed. The combined effect of the reduced thermal gradient and the heterogeneous nucleation from the coaxial wire feeding played an important role in determining the refined microstructures in coaxial LMWD.

An investigation on the effect of different multi-step heat treatments on the microstructure, texture and mechanical properties of the DED-produced Ti-6Al-4V alloy

This work deals with the effect of different heat treatments on directed energy deposition (DED)-produced Ti-6Al-4V samples. Annealing treatments at 1050 °C followed by different cooling rates were conducted to allow a complete recrystallization of the microstructure and remove the columnar prior-β grains, thus increasing the overall isotropy of the material. An agine treatment at 540 °C was also performed for further microstructural stabilization. The microstructures, textures and mechanical properties were then assessed. Due to the heat treatments, greatly differing microstructures were achieved in an equiaxed grain morphology. However, a “grain memory” effect was detected which resulted in the grains size increasing along the height of the samples. This effect was correlated to the intrinsic prior-β grain width variation along Z on the as-printed specimens, typical of the DED technology. Electron backscatter diffraction analyses proved that the intensity of the preferential directions increased after the heat treatments, likely due to the crystallographic variant selection mechanisms taking place when the samples cool down from the annealing temperature. This effect is also influenced by the significant difference in terms of prior-β grains sizes between the heat-treated and the as-printed specimens. To sum up, a complete homogenization of the material via heat treatment above the β-transus temperature proved to be challenging. In fact, the data suggest that the intrinsic texture-related anisotropy granted by the manufacturing process is very difficult to be eliminated.

Effect of Aging and Cooling Path on the Super β-Transus Heat-Treated Ti-6Al-4V Alloy Produced via Electron Beam Melting (EBM).

This work focuses on the effect of different heat treatments on the Ti-6Al-4V alloy processed by means of electron beam melting (EBM). Super β-transus annealing was conducted at 1050 °C for 1 h on Ti-6Al-4V samples, considering two different cooling paths (furnace cooling and water quenching). This heat treatment induces microstructural recrystallization, thus reducing the anisotropy generated by the EBM process (columnar prior-β grains). Subsequently, the annealed furnace-cooled and water-quenched samples were aged at 540 °C for 4 h. The results showed the influence of the aging treatment on the microstructure and the mechanical properties of the annealed EBM-produced Ti-6Al-4V. A comparison with the traditional processed heat-treated material was also conducted. In the furnace-cooled specimens consisting of lamellar α+β, the aging treatment improved ductility and strength by inducing microstructural thickening of the α laths and reducing the β fraction. The effect of the aging treatment was also more marked in the water-quenched samples, characterized by high tensile strengths but limited ductility due to the presence of martensite. In fact, the aging treatment was effective in the recovery of the ductility loss, maintaining high tensile strength properties due to the variation in the relative number of α/α’ interfaces resulting from α’ decomposition. This study, therefore, offers an in-depth investigation of the potential beneficial effects of the aging treatment on the microstructure and mechanical properties of the EBM-processed super β-transus heat-treated Ti-6Al-4V alloy under different cooling conditions.

Variant selection in additively manufactured alpha-beta titanium alloys

The crystallographic arrangements of the α-phase variants in α-β titanium alloys remains less identified due to the crystallographic complexity involved while being essential to understand the α-β microstructural intricacy. To improve the current understanding, specimens of two columnar-grained α-β Ti alloys (Ti-6Al-4V and Ti-6Al-2Sn-4Zr-2Mo) and two equiaxed-grained α-β Ti alloys (Ti-6Al-4V and Ti-4Al-2V) were fabricated by laser metal powder deposition (LMD). Electron backscatter diffraction (EBSD) analyses were applied to more than 105 α-phase variants in each alloy. The results revealed that the Type 4 α/α variant boundary ([10¯553¯]/63.26∘) is prevalent in the two columnar-grained α-β alloys while the Type 2 α/α variant boundary ([112¯0]/60∘) is common in the two equiaxed-grained α-β alloys. Further EBSD characterisation indicates that α-variant selection tends to be more prevalent in equiaxed prior-β grains, featured by the Category I triple-α-variant clusters, which mostly terminate on dense {101¯1} planes with lower boundary energy. Conversely, columnar prior-β grains show significant Category II triple-α-variant clusters, which mostly terminate on less dense {41¯3¯0} planes with higher boundary energy. Self-accommodation to compensate for the β→α transformation strain is assumed to be the major underlying mechanism. The implications of these findings for understanding the tensile strengths are discussed in conjunction with the Schmid factor of α-variants calculated in columnar- and equiaxed-grained Ti-6Al-4V.

The Anisotropic Electrochemical Machinability of Laser Cladding Deposited Ti6Al4V Alloy in NaCl Solution

The hybrid manufacturing method of laser cladding deposition (LCD) additive manufacturing and electrochemical machining (ECM) is a promising approach to advanced manufacturing technology for difficult machined materials. The anisotropic electrochemical performance of LCD-produced Ti6Al4V alloy was studied in 15 wt.% NaCl solution by polarization curve measurements and ECM tests. The horizontal-plane (X0Y plane) exhibits a more stable passive film in both static electrolyte and low current density ECM processes than the vertical-plane (X0Z plane). Additionally, the horizontal-plane exhibits a higher material removal rate and more consistent dissolved surface roughness in comparison with the vertical-plane during the high current density ECM process. The microstructure of the LCD-produced Ti6Al4V alloy on the horizontal-plane consisted of equiaxed-like prior-β grains and slightly finer α-laths but was composed by columnar prior-β grains and coarser α-laths on the vertical-plane. These differences in the microstructural characteristics produce the distinctions observed in the electrochemical dissolution behavior and electrochemical machinability on the horizontal- and vertical-planes.

Microstructure modification of additive manufactured Ti-6Al-4V plates for improved ballistic performance properties

• Additive manufacturing of Ti-6Al-4V armour plates for ballistic testing. • Ballistic limit dependent on build direction due to microstructure anisotropy. • Lamellar α + β from martensitic decomposition resulted in better ballistic limit. Titanium alloys such as Ti-6Al-4V offer a potential lightweight alternative to traditional armour steels for ballistic protection due to their reduced density of approximately 60 % that of steel and tensile properties better than rolled homogenous armour steel. The manufacture of metallic armour often requires substantial thermomechanical processing to meet necessary ballistic performance specifications and thus restricts the complexity of armour designs. Additive manufacturing of Ti-6Al-4V has matured significantly in recent years, achieving outstanding mechanical properties in the as-built condition. In this study, Ti-6Al-4V plates were additively manufactured using both laser powder bed fusion and direct laser metal deposition for ballistic testing. The plates were built in different orientations and subjected to pre-heating or post heat-treatment to investigate the microstructural effect on the ballistic velocity limit (V 50 ). The results show that plates with lamellar microstructure formed through martensite decomposition had higher V 50 compared to lamellar microstructure formed via slow cooling through the β-transus. The post heat-treatment increased the V 50 due to coarsening of the α-lath and stress relief. It is also apparent that anisotropy of the microstructure, specifically the columnar prior-β grains, affects the ballistic performance. A higher V 50 was achieved when the columnar grains were aligned perpendicular to the projectile impact direction.

Developing ductile and isotropic Ti alloy with tailored composition for laser powder bed fusion

Laser powder bed fusion (LPBF) is an advanced technology to create metallic components with complex geometry. Ti-6Al-4V (Ti64) is one of the most frequently used materials for LPBF. The intrinsic high cooling rates and ultra-high directional thermal gradient of melt, however, lead to a hierarchical structure composed of fine martensitic α' within columnar prior-β grains in LPBF Ti64. This microstructure results in poor ductility and strong mechanical anisotropy in as-built Ti64 components, which largely limit their applications. Here, we report that the above shortcomings can be overcome by tailoring the alloy composition. Specifically, by reducing the aluminum content from 6 wt% to 4 wt%, the resultant LPBF Ti-4Al-4V (Ti44) alloy exhibits substantially improved ductility and mechanical isotropy. These improvements are attributed to grain refinement during solidification and the activation of multiple slip modes and twinning in the as-built material during deformation. This work offers a simple strategy to design new titanium alloys for LPBF with significantly improved ductility and isotropy.

Microstructural features of Ti-6Al-4V manufactured via high power laser directed energy deposition under low-cycle fatigue

Laser additive manufacturing (LAM) technique has unique advantages in producing geometrically complex metallic components. However, the poor low-cycle fatigue property (LCF) of LAM parts restricts its widely used. Here, the microstructural features of a Ti-6Al-4 V alloy manufactured via high power laser directed energy deposition subjected to low-cycle fatigue loading were studied. Before fatigue loading, the microstructure of the as-deposited parts was found to exhibit a non-homogeneous distribution of columnar prior-β grains (200–4000 μm) at various scanning velocities (300–1500 mm/min) and relatively coarse α-laths (1.0–4.5 μm). Under cyclic loading, fatigue microcracks typically initiated within the aligned α phases in the preferred orientation (∼45° to the loading direction) at the surface of the fatigue specimens. Fatigued Ti-6Al-4 V exhibited a single straight dislocation character at low strain amplitudes (<0.65 %) and dislocation dipoles or even tangled dislocations at high strain amplitudes (>1.1 %). In addition, dislocation substructure features, such as dislocation walls, stacking faults, and dislocation networks, were also observed. These findings may provide opportunities to understand the fatigue failure mechanism of additive manufactured titanium parts.

Distinction in electrochemical behaviour of Ti6Al4V alloy produced by direct energy deposition and forging

The relationship between microstructural characteristics and anodic dissolution behaviour plays a crucial role in the process control of the electrochemical machining technology (ECM). An additive-manufactured Ti6Al4V alloy produced by direct energy deposition (DED) exhibited a finer lamellar α+β structure within the considerably coarser columnar prior-β grains as compared to the traditional forged Ti6Al4V alloy consisting of equiaxed α and transformed β phases. The electrochemical anodic behaviour of DED-produced Ti6Al4V alloy was investigated in a 15-wt.% NaCl solution and compared with that of the forged Ti6Al4V alloy. Electrochemical measurements showed that the DED-produced Ti6Al4V exhibited higher resistance to corrosion and lower electrochemical machinability than did the forged Ti6Al4V alloy. The high phase boundary density, originating from the refinement of constituent phases, increased the stability of the passive film formed on the surface of the DED-produced Ti6Al4V, thereby improving the corrosion resistance, while the high fraction of β phase in the Ti6Al4V deposit decreased the rate of anodic dissolution. The lower composition difference of solutes of DED-produced Ti6Al4V was beneficial to its higher resistance to corrosion. The fine and lath-type α phases led to a competitively high level of microscopic flatness of the Ti6Al4V alloy after the electrochemical dissolution.