Additive Manufacturing Samples Research Articles

Anisotropic polymer components with desired elastic properties manufactured through fused filament fabrication additive manufacturing

AbstractFused filament fabrication (FFF) is a popular additive manufacturing (AM) process, primarily used for fabricating polymer components. Optimizing the mechanical properties of FFF components, such as their elastic moduli, is crucial in many applications. This study focuses on adjusting the elastic properties of polymer components manufactured through FFF process by selecting appropriate process parameters. The elastic constants of the anisotropic FFF components are measured by using ultrasonic testing (UT). Response surface methodology (RSM) is employed to determine the optimal settings for these parameters to achieve the desired elastic properties. The effects of layer thickness, printing speed, and raster angle on Young's modulus are explored. Analysis of variance (ANOVA) is used to identify the contributions of each process factor on the output responses. According to ANOVA results, the optimal conditions identified are: a printing speed of 2040 mm/min, a layer thickness of 0.2 mm, and a raster angle of 29°. These conditions collectively achieved the maximum Young's modulus. The differences between the predicted and measured moduli for all responses are less than 5%. The structural factors influencing the results are examined by analyzing the fracture surfaces of the tensile testing (TT) specimens with field emission scanning electron microscopy. Additional measurements of other properties, including ultrasound velocity and wave attenuation, are conducted on the samples. The findings indicate that optimizing the parameters by setting them to their minimum values does not only improve the maximum elastic modulus in specific directions but also reduces attenuation. It is concluded that the desired elastic modulus for a component can be achieved by properly adjusting the process parameters.Highlights Optimizing AM parameters to achieve the desired elastic properties of FFF samples. Examining the effects of each AM parameter by utilizing ANOVA and RSM methods. Measuring the anisotropic elastic properties of AM samples by UT. Verifying UT results through TT and measuring attenuation.

On the role of geometrically necessary dislocations in void formation and growth in response to shock loading conditions in wrought and additively manufactured Ta

This study investigates the role of geometrically necessary dislocations (GNDs) and microstructure on void nucleation and growth in wrought and additively manufactured (AM) tantalum subjected to high-strain rate loading. Multi-modal 3D data was collected using TriBeam tomography to calculate GND densities and their spatial relationship to voids. A microstructural comparison between the wrought and AM samples identified distinct void shapes and locations, with intragranular voids and more spherical voids frequently observed in the AM dataset. Results indicate that voids preferentially form at both high-angle grain boundaries and low-angle subgrain boundaries, the latter of which are frequently observed in the AM material. Through a radial distribution analysis of all voids in the datasets, significant GND localization to near-void-surface regions was observed in both samples. 3D crystal plasticity simulations were employed to extend the experimental observations, revealing higher void growth rates in [111] oriented grains when compared to [001] grains. The simulations also suggest that GNDs can be generated as part of the void growth process, with more GND accumulation for growth in a [111] grain than a [001] grain. These findings provide valuable insights into the links between nanoscale void nucleation, mesoscale void growth, and microstructural effects in dynamically loaded tantalum.

Laser powder bed fusion of pure copper electrodes

This study explores the fabrication and characterization of a pure copper electrode for an EDM equipment using laser powder bed fusion (LPBF) and comparing its performance with an original cast sample. The microstructural, mechanical, electrical, thermal, and corrosion characteristics of the samples were analyzed. The microstructure of the additively manufactured (AM) sample exhibited superior mechanical properties, with an 18 % increase in ultimate tensile strength and more than two times greater elongation in comparison with those of the cast sample. Moreover, the electrical and thermal conductivity coefficients of the AM sample were found to be consistent with industry standards as 5.52 × 107 S/m and 361 W/mK, respectively. Additionally, the potentiodynamic polarization corrosion test results of the AM sample further exhibited superior corrosion resistance in terms of the corrosion potential particularly in a 3.5 % NaCl environment. Advanced electron microscopy techniques were used to investigate the differences in the properties of the AM and cast samples and further shed light on the superior properties of the LPBF counterpart. Despite challenges in manufacturing pure copper components through LPBF, this study demonstrates the feasibility of producing a functional part that competes effectively with cast counterparts and excels in certain aspects.

Ballistic characterization of additively manufactured extrusion deposited thermoplastic composite plates

Additive manufacturing (AM) is rapidly emerging in high performance applications such as army ground vehicles, automotive and transportation. However, the response of AM parts/components to extreme loading such as high velocity impacts is less studied. In this work, the performance under ballistic impact of AM panels is evaluated using a medium velocity gas gun, generating projectile velocities up to 400 m/s. The preferential print orientation properties are considered in order to evaluate whether the panels exhibit isotropic or anisotropic behavior under impact. Surface morphology is investigated by milling the beads smooth on samples and comparing the impact on as-printed samples to those that are smoothed. The effect of nickel chromium micron (nichrome) wire embedded in the AM panels (during print) of polycarbonate-carbon fiber (PC-CF) and polycarbonate-glass fiber (PC-GF) are explored. Thermoplastic polyurethane-acrylonitrile butadiene styrene/carbon fiber (TPU-ABS/CF), Acrylonitrile butadiene styrene-carbon-fiber (ABS-CF) AM samples absorbed >50% of the impact energy. The ballistic performance was noted to be in the following order – ABS-CF > TPU-ABS/CF > PC. Scanning electron microscopy (SEM) was conducted to study the interface between the nichrome wire and the polymer-fiber matrix. This work is the first of its kind exploring into the capabilities of AM panels as ballistic materials. This study leads the way for developing AM panels that are easily manufactured and exhibit superior ballistic resistance.

Enhancement of surface characteristics of additively manufactured γ-TiAl and IN939 alloys after laser shock processing

The enhancement in laser technology opened up new methods such as additive manufacturing (AM) of metals. While AM offers high design flexibility and reduced material usage, it can also produce problematic parts due to poor surface quality. A variety of post-processing techniques are available to address the drawbacks associated with the surface properties of AM. Laser Shock Processing (LSP) is one of the unique methods that induces compressive residual stress (CRS) on the surface and subsurface by creating severe plastic deformation. In this study, two critical aerospace alloys (γ-TiAl and IN939) were manufactured through two different methods called Powder Bed Fusion with Electron Beam (PBF-EB) and Powder Bed Fusion with Laser Beam (PBF-LB). Subsequently, AM samples were investigated to observe single layer LSP effects on the surface. The results of the laser peening process were determined by residual stress, microhardness and surface roughness measurements. The residual stress profiles showed that LSP significantly induces CRS on the surfaces of AM alloys. For the γ-TiAl and IN939 samples, the maximum values of CRS and depth of CRS were −460 MPa/1000 µm and −516 MPa/700 µm, respectively. Similarly, the microhardness of the materials was increased by 44.4 % for γ-TiAl and 18.2 % for IN939 by laser post-processing. In addition, a comparison of the roughness of the unground and ground AM samples was carried out. Depending on the surface condition of the AM samples, LSP had different outcomes. For example, the extreme roughness of the AM samples was partially reduced by the thermal effects of the high-energy laser shots. When comparing the roughness values in terms of Ra and Rz, there were decreases in the range of 14.7–21.3 % and 3.34–39.3 % for unground IN939 samples. However, for unground γ-TiAl samples, depending on the direction of measurement, roughness variations were observed as a 0.99 % decrease − 5.3 % increase for Ra and a 2.2 % decrease − 14.2 % increase for Rz. The roughness values for ground samples of both alloys were drastically increased, varying between 42.1 % and 7x increase. Sa values were recorded on unground AM samples. For IN939 and γ-TiAl samples these values decreased by 8.41 % and 15.8 % respectively.

Improving the Mechanical and Electrochemical Performance of Additively Manufactured 8620 Low Alloy Steel via Boriding

In this study, mechanical and electrochemical performance of borided additively manufactured (AM) and wrought 8620 low alloy steel were investigated and compared to their bare counterparts. The microstructure of borided 8620 exhibited the presence of FeB and Fe2B phases with a saw tooth morphology. Both AM and wrought samples with boride layers showed a similar performance in hardness, wear, potentiodynamic polarization (PD), electrochemical impedance spectroscopy (EIS), and linear polarization resistance (LPR) experiments. However, borided steels exhibited about an 8-fold increase in Vickers hardness and about a 6-fold enhancement in wear resistance compared to bare ones. Electrochemical experiments of borided specimens (both AM and wrought) in 0.1 M Na2S2O3 + 1 M NH4Cl solution revealed a 3–6-fold lower corrosion current density, about a 6-fold higher charge transfer resistance, and about a 6-fold lower double-layer capacitance, demonstrating an improved corrosion resistance compared to their bare counterparts. Post-corrosion surface analysis revealed the presence of thick sulfide and oxide layers on the bare steels, whereas dispersed corrosion particles were observed on the borided samples. The enhanced wear and electrochemical performance of the borided steels were attributed to the hard FeB/Fe2B layers and the reduced amount of adsorbed sulfur on their surface.

CT-Based Dimensional Metrology for Quality Assessment of the Internal Structure of Additive Manufactured Aluminum Parts

Two common types of internal defects of additively manufactured (AM) samples are lack-of-fusion and gas-entrapped porosities. These internal defects can have different physical origins and particular local characteristics (e.g., different shape, size). Thus, the use of reliable non-destructive inspection techniques is essential for the accurate assessment of integrity, allowing the applicable AM processing parameters correction. To overcome this challenge, this work aims to evaluate the accuracy of volumetric characteristics measured by computed tomography for porosity evaluations in AM samples, including assessment of measurement uncertainty. The effect of different cumulative thickness on the evaluated measurements accuracy is also assessed. The results show that deviations of defect size measurements can be below 2% if the proposed procedure is followed. In addition, the expanded uncertainty can be up to 10% of the measured magnitude when the cumulative thickness is increased to 70 mm. The physical relationships obtained between the cumulative thickness and the individual measurements are also presented.

Ratcheting–Fatigue Damage Assessment of Additively Manufactured SS304L and AlSi10Mg Samples under Asymmetric Stress Cycles

The present study aims to investigate the interaction of ratcheting and fatigue phenomena for additively manufactured (AM) samples of SS304L and AlSi10Mg undergoing uniaxial asymmetric stress cycles. Overall damage was accumulated through fatigue and ratcheting on AM samples prepared from three-dimensional-printed plates along vertical and horizontal directions. Fatigue damage was evaluated based on the strain energy density fatigue approach and ratcheting damage was calculated through use of an isotropic–kinematic hardening framework. The isotropic description through the Lee–Zavrel (L–Z) model formed the initial and concentric expansion of yield surfaces while the Ahmadzadeh–Varvani (A–V) kinematic hardening rule translated yield surfaces into the deviatoric stress space. Ratcheting of AM samples was simulated using finite element analysis through use of triangular and quadrilateral elements. Ratcheting values of the AM samples were simulated on the basis of Chaboche’s materials model. The predicted and simulated ratcheting damage curves placed above the experimental fatigue–ratcheting experimental data while predicted fatigue damage curves collapsed below the measured values. The overall damage was formulated to partition damage weights due to fatigue and ratcheting phenomena.

Ratcheting assessment of additively manufactured alloys through the hardening framework: Analysis and simulation

The present study intends to evaluate the ratcheting response of the additively manufactured (AM) samples made of Al 4043, SS316L, and Ti–6Al–4V alloy through hardening rules and finite element analysis. The hardening framework consisted of Ahmadzadeh‐Varvani (A-V) kinematic hardening rule and an isotropic hardening description by Lee-Zavrel (L-Z). Yield surface evolution was evaluated for (i) AM samples taken from mid and top sections of the 3D printed plate, and (ii) heat-treated samples. The Chaboche’s materials model was employed to assess ratcheting of AM samples through use of finite element method. The choice of hardening models affected yield surface translations over the loading process. The predicted and simulated ratcheting curves were found in close agreements falling below those of measured values.

Surface Integrity of Cryogenically Finished Additively Manufactured and Conventional Ti-6Al-4V Alloy

Additive manufacturing (AM) is used for the fabrication of solid components of complex geometries for customized applications. However, AM-fabricated components frequently require finishing operations such as abrasive grinding, which causes a different surface characteristic compared to the conventionally manufactured components. Thus, it is essential to study the effect of process parameters and the heat treatment on surface quality of the AM components because these may behave differently to the conventional manufactured components. In this study, surface characteristics of AM samples of Ti-6Al-4V with a cryogenically cooled finishing operation is compared with that of conventionally processed samples. The samples under investigation were fabricated by two different methods, namely, Direct Metal Laser Sintering (DMLS) and conventional processing. The effect of the two processes on surface characteristics, such as microhardness, surface roughness, X-ray diffraction (XRD), and mechanical properties has been studied. The average surface roughness from cryogenic grinding was reduced by 27.25% and 23.15% for the AM, and 30.08% and 29.13% for conventional samples, as compared to dry and moist conditions, respectively. The finished DMLS and conventional samples showed increase of microhardness by 14.07%, 14.27%, 17.54% and 17.48%, 8.06%, 38.68%, in dry, moist, and cryogenic conditions, respectively. In cryogenic conditions, as the DOC and table feed increased, a greater increase in peak broadening was observed. The peak broadening in XRD of finished DMLS components indicates that a significant level of plastic deformation occurred compared to the finished conventionally manufactured Ti-6Al-4V samples, which suggests that the DMLS samples are more sensitive to the finishing process. Compared to dry and moist grinding, cryogenic grinding was found to have the smallest grains in the layer just below the surface. The impact of cryogenic cooling on surface properties of AM Ti-6Al-4V samples is higher as compared to that on conventionally processed Ti-6Al-4V samples.

High temperature friction and wear of post-machined additively manufactured tool steel during sliding against AlSi-coated boron steel

In recent years, additive manufacturing (AM) of metallic materials has achieved the production of virtually fully dense parts, extending the range of potential applications. There is a growing interest in the use of AM to produce forming tools for hot stamping. The possibilities of locally tailoring the die material to tackle wear challenges and producing more complex geometries to improve die cooling are key-features driving that interest. However, there is a lack of knowledge concerning the tribological behavior of AM materials, particularly at high temperature, as well as the influence surface finishing processes after additive manufacturing. The aim of this study is to investigate the high temperature friction and wear behavior of a tool steel, produced by selective laser melting, within the context of hot forming of AlSi-coated boron steel. A high temperature strip drawing tribometer was used to perform sliding tests at 600 °C and 700 °C. Three different surface finishes were used for the AM samples: ground, milled and shot-blasted. A conventionally produced steel with the same chemical composition and a ground surface finish was used as a reference. At 600 °C, a similar stable coefficient of friction of 0.4 was observed for both materials and all surface topographies. At 700 °C, all tests resulted in a sudden increase in friction up to 0.9 due to local rupture of the AlSi-coating, severe material transfer and ploughing. The wear mechanisms observed for the ground surfaces, both AM and reference tool steel, were a combination of adhesive material transfer and abrasive material removal that promotes material pile-up, resulting in wedge formation on the tool steel surface. The characteristic wedge formation was not common in the milled surface. This is attributed to strain-hardening and topographical features from the finishing process. For the shot-blasted AM surface, deformation and flattening of the large asperities was observed, as well as material transfer. Subsurface deformation associated with high adhesion during sliding was observed, mainly for the ground surfaces. The milled surface resulted in the least amount of tool steel transfer onto the counter body, while the shot-blasted one resulted in the largest amount. AM and reference ground tool steel showed very similar friction and wear behavior in this tribosystem.

Anisotropic spall failure of additively manufactured 316L stainless steel

The dynamic high strain rate tensile (spall) failure of additively manufactured (AM) materials is an area of great interest but much less understood than material failure under other loading regimes. The research presented here examines the effects of microstructure anisotropy in 316L stainless steel fabricated by laser powder bed fusion (LPBF) on its spall failure and properties. Plate-on-plate impact experiments were performed using an 80-mm gas gun to investigate the spall behavior of AM fabricated sample discs with impact along the perpendicular and parallel orientations relative to build directions. Experiments were also performed on wrought 316L stainless steel as baseline material with uniform equiaxed grain microstructure for comparison with the AM material of same composition. The spall experiments involved free-surface velocity profiles measured using Photon Doppler Velocimetry (PDV) to capture the spall pull-back signals, combined with post-mortem analysis of the microstructure of soft-recovered impacted samples. In the case of AM samples, spall failure initiated preferentially at melt pool boundaries in both impact directions. The spall plane location and spall strength, however, were both heavily influenced by the orientation of the impact direction relative to the build direction in the AM samples. The spall behavior is also observed to be more complex in the samples impacted perpendicular to the build (through-thickness) direction, due in large part to the orientation of the microstructural features such as melt pool boundaries, laser scan tracks, and general grain morphology.

Performance parameters for evaluating pore detection ability of computed tomography systems

Industrial x-ray computed tomography (CT) has become an important tool for detecting and characterizing pores in workpieces produced through additive manufacturing (AM). However, a procedure to quantify the ability of a CT system to reliably detect pores, ideally in a non-destructive manner and before the actual analysis process, is still being researched. Previous approaches can either only be carried out at a great expense and destructively, or have not yet been validated in the actual case of pore detection. This work presents a potential reference object and corresponding performance parameters, the metrological structural resolution and the grey-scale resolution. To investigate their suitability for predicting the ability to detect pores, both the reference object, and special pore-containing AM samples were examined using the same CT settings. Linking the performance parameters with the pore detection rate of the AM samples showed that structural resolution, but also image sharpness, are suitable parameters.

Sensitization of 316L Stainless Steel made by Laser Powder Bed Fusion Additive Manufacturing

Additively manufactured (AM) 316L stainless steel (SS) manufactured by laser powder bed fusion (L-PBF) and wrought 316L SS were subjected to sensitization heat treatments at 700°C up to 100 h. Using two evaluation methods, double-loop electrochemical potentiokinetic reactivation (DL-EPR) and ditching tests, degree of sensitization (DOS) and intergranular corrosion (IGC) susceptibility was evaluated. It was found that the wrought samples showed slightly lower IGC susceptibility compared to their AM counterpart. DOS and IGC attacks increased with sensitization time for all samples. Dislocation cellular structures were found to have little to no impact on DOS and IGC for the AM samples. Sensitized at 100 h, the AM sample showed significant Cr depletion along high-angle grain boundaries (12.35 wt% on average) and exhibited Cr carbide precipitation. Mo-rich particles along grain boundaries were also observed. The DL-EPR test attacks the surface oxide film and grain boundaries while the ditching test attacks the melt pool boundaries and grain boundaries (IGC and pitting). Changes to the DL-EPR and ditching standards for AM application have been proposed in this work.

Ultrasonic methods for the characterization of additively manufactured 316L stainless steel

This research utilizes linear and nonlinear ultrasonic techniques to establish a linkage between microstructure and macroscale mechanical properties of additively manufactured (AM) stainless steel 316L samples. The specimens are manufactured using two methods: laser-powder bed fusion and traditional wrought manufacturing. Using the nonlinear ultrasonic method of second harmonic generation, the acoustic nonlinearity parameter is estimated in samples with different heat treatment levels intended to alter microstructural and mechanical properties. Linear ultrasonic parameters including wave speed and resonant frequency are additionally measured. Mechanical properties are obtained through tensile testing of coupons corresponding to the test samples. Microstructural information for the samples is obtained using electron backscatter diffraction to help elucidate the relationships between microstructure, mechanical properties, and ultrasonic response. Results indicate correlations between the nonlinearity parameter and both ultimate tensile strength and yield strength, where nonlinearity generally decreases as sample strength increases, particularly in the AM samples. We hypothesize that microstructural evolution of grain characteristics across different heat treatments influences trends in measured nonlinearity, as well as substructures at smaller scales such as dislocations. These results show promising evidence for the feasibility of AM parts qualification using nondestructive nonlinear ultrasonic testing.

Ultra-fast laser ultrasonic imaging method for online inspection of metal additive manufacturing

In this paper, an ultra-fast laser ultrasonic imaging method is proposed to provide an efficient online monitoring of additive manufacturing (AM) processing. The innovations of the proposed ultrafast imaging method in this research mainly include two parts. Firstly, multi-circle combined scanning strategy and defect location algorithm is constructed to improve the detection efficiency. Secondly, a surface wave focusing algorithm (SWFA) is established to solve the problem of low SNR induced by rough surface signals. The AM samples containing four types of surface and inner defects are designed and manufactured to verify the detectability and quantitative accuracy of the proposed method. Systematically comparisons between our proposed method with the traditional laser ultrasonic imaging are also discussed. The result indicated that the proposed ultra-fast imaging method is efficient for detecting the surface and sub-surface defects in the condition of low SNR caused by rough surface of AM components. The minimum detectable defect reaches 0.1 mm and the quantitative error could low down to 6.46% when the defect size is larger than 0.2 mm. Compared with the C-scan imaging method, the method proposed in this paper can improve the scanning efficiency of single-layer inspection by more than 300%, which is meaningful to improve the efficiency of metal additive manufacturing.

Comparative study of additively manufactured and reference 316 L stainless steel samples – Effect of severe shot peening on microstructure and residual stresses

The as-built selective laser melted (SLM) austenitic stainless steel 316 L components are characterized by presence of quality related concerns such as tensile residual stresses, poor surface finish, etc. These issues may prove to be detrimental during the actual usage of components and could result in poor mechanical performance. Therefore, it is important to perform the apt post processing such as heat treatment and shot peening to tailor such problems and facilitate improved mechanical performance. In the present work, additively manufactured (AM) 316 L samples were subjected to shot peening with different parameters including the severe shot peening (SSP) procedure. The identical shot peening protocol was also applied to reference samples to evaluate the comparable response. Both the shot peened reference and AM samples were studied for residual stresses, surface topography, microhardness, and the corresponding microstructure. The results indicated, that SSP induced higher values of compressive residual stresses deeper into the samples. This was accompanied by reduced surface roughness, increased grain refinement depth, and higher microhardness near the surface. The SSP resulted in transformation of original austenite to martensite near the surface in the reference samples.

Fatigue and fracture of additively manufactured polyethylene terephthalate glycol and acrylonitrile butadiene styrene polymers

This paper aims to study and compare the static tensile properties and Low Cycle Fatigue (LCF) deformation behavior of Additively Manufactured (AM) samples made of two commonly used polymers: Polyethylene Terephthalate Glycol (PET-G) and Acrylonitrile Butadiene Styrene (ABS). Such materials are commonly in use in the Material Extrusion (ME) AM technologies – especially in Fused Deposition Modelling (FDM) or Fused Filament Fabrication (FFF). That kind of approach would be useful to understand the fracture phenomena of AM parts obtained by means of FDM/FFF technologies which are entirely different than in the conventionally made material, because of the characteristic layered structure of AM parts. The study has been supplemented by additional fracture analysis of AM samples subjected to LCF tests. The conducted research exposed an increased LCF of PET-G samples (36050 cycles at constant strain equal to ε = 0.40%) in comparison to ABS (24586 cycles at the same strain level). At the same time, PET-G samples indicated a significant material softening during LCF testing. Such a phenomenon was better described by additional analysis with the use of the Morrow equation which indicated quasi-brittle cracking with visible brittle fracture phenomena in PET-G samples.

Alternating chempolishing and electropolishing for interior and exterior surface finishing of additively manufactured (AM) metal components

Additively manufactured (AM) components’ surface finishing is crucial in adopting them for intended applications in challenging environments involving fatigue, corrosion, high temperature, and nuclear radiation. In our prior research, chempolishing (C) was utilized as an electroless etching process that uniformly smoothens complex AM components’ accessible interior and exterior surfaces (Tyagi et al. Additive Manufacturing, 25:32–38, 22). A wide range of electropolishing (E) has been demonstrated for AM surface finishing. However, electropolishing can impact a surface that can be juxtaposed to counter electrode and can yield a very smooth surface to sub-micrometer level roughness. However, a knowledge gap exists about the impact of applying both approaches on the same surface one after another and what new advantages may arise because of combining two methods. This paper uses dual-stage liquid-based surface finishing strategies produced by alternating the chempolishing (C) and electropolishing (E) steps. Two dual-stage surface finishing approaches, i.e., chempolishing followed by electropolishing (CE) and electropolishing followed by chempolishing (EC), were performed on the 316 stainless AM steel component. Impacts of EC and CE approaches were compared with single-stage C and E surface finishing approaches. An optical microscope and mechanical profilometer were utilized to investigate the wide range of surface roughness parameters. CE and EC produced Ra ~ 1.4 µm and ~ 1.6 µm, respectively. Surface roughness on CE- and EC-treated AM samples was lower than those individually treated by C and E approaches. Scanning electron microscopy provided further insights into the microstructural difference between CE- and EC-treated AM samples. This paper reports a liquid contact angle study on CE- and EC-treated AM samples to provide insights into the relative difference in surface energy that is crucial for making coatings on AM parts. A spectroscopic reflectance study was also employed to register the difference in physical properties of AM components treated with CE and EC approaches. This study reveals industrially practicable interior and exterior surface finishing approaches for complex AM metal components that require minimum tooling and real-time process monitoring.

Corrosion behavior of near‐alpha titanium alloy fabricated by additive manufacturing

AbstractThe purpose of this study was to investigate the corrosion behavior of Ti–6Al–Mo–1.5V–2Zr near‐alpha titanium alloy fabricated by additive manufacturing (AM). Titanium alloy specimens were fabricated by electron beam melting (EBM) and laser metal deposition (LMD). The same titanium alloy manufactured by traditional technology (TT) was used as a control. The correlations between corrosion resistance, microstructure and phase composition of titanium alloys fabricated by different technologies were investigated, through the use of electrochemical corrosion testing, scanning electron microscopy, X‐ray diffraction, and hardness testing. In this study, it was shown that the corrosion resistance of AM samples is lower than TT samples. The corrosion resistance of AM samples was attributed to the presence of more α′ martensite and less β‐Ti phases in the microstructure of titanium alloy than for TT samples. The electrochemical results suggest that titanium alloy fabricated by EBM has better corrosion resistance in 20% HCl solution at room temperature compared to titanium alloy fabricated by LMD.