Inhomogeneous Microstructure Research Articles

Microstructure evolution and fracture behavior of 2060 Al[sbnd]Li alloy by laser welding with TiC nanoparticle-reinforced filling wire

Laser welding could provide thermal concentration and penetration to alloys, making microstructural diversity that determines mechanical properties. During laser welding process of aluminum alloys, one of the most important characteristics is the inhomogeneity of microstructure. The study demonstrated microstructure transformation of 2060 aluminum-lithium (AlLi) alloy in laser welding technique using TiC nanoparticle-reinforced filling wire to tailor mechanical properties. Furthermore, the study unveils the microstructural configuration achieved during laser welding of the 2060 AlLi alloy, along with its fine-scale mechanical behavior. The results show that the microstructure of weld seam (WS) with TiC nanoparticle-reinforced ER2319 filling wire was dominated by fine equiaxed crystal, which indicated that the addition of nanoparticles promoted the transformation from columnar crystal to equiaxed crystal. Compared with conventional ER2319 filler wire, the grain size with adding TiC nanoparticles reduced by 47 %, and the strong texture feature of Al-matrix on (001) base plane tended to disappear. Furthermore, the tensile strength and elongation of WS were increased by 8.6 % and 195.5 %, respectively. The direction of crack propagation is deflected under filler ER2319CT wire, gradually tends to be perpendicular to the load direction. This is attributed to the fact that the dispersed TiC particles in WS hinder the movement and migration of dislocations resulting in an increase of strength.

The nature of the frequency dependence of the adiabatic temperature change in Ni50Mn28Ga22-x(Cu, Zn)x Heusler alloys in cyclic magnetic fields

This study presents the results of direct measurements of the adiabatic temperature change (∆Tad) in Ni50Mn28Ga22−x(Cu, Zn)x (x = 0; 1,5) alloys in cyclic magnetic fields of 0.62 and 1.2 T at frequencies f= 1, 5, 10, and 20 Hz. The substitution of zinc and copper for the initial composition resulted in a decrease in ∆Tad and a stronger frequency dependence. The strong frequency dependence of ∆Tad near TC in the Ni50Mn28Ga22−x(Cu, Zn)x system is due to the inhomogeneous microstructure and the coexistence of martensite-austenite phases, which give rise to two simultaneously acting mechanisms. Firstly, the addition of Zn and Cu increases the coercive force HC, resulting in an increase in the viscosity coefficient. Secondly, an increase in the frequency of the cyclic magnetic field (i.e., an increase in the field sweep rate) leads to the same effect, increasing the viscosity coefficient. Which, in our opinion, is the reason for the frequency dependences of ∆Tad near TC. The study found that the specific cooling power (SCP) for the Ni50Mn28Ga22 sample in a cyclic magnetic field of 1.2 T increased with frequency, reaching 4.75 W/g at 20 Hz, which is 14.1 times greater than at 1 Hz. This suggests that, under conditions of sufficient heat exchange, the cooling efficiency of a magnetic refrigerator can be greatly improved by increasing the operating frequency.

Effects of the inhomogeneous microstructures on buffer layer ablation failure in high voltage cables

In recent years, growing attention has been paid to the buffer layer ablation failure in high voltage cables. The buffer layer was always regarded as a homogeneous material in previous studies, while in this paper, the effects of its structural inhomogeneity on failure is found unneglectable. The buffer layer is recognized to be a porous material comprising fibers and air pores through microscopic characterization. Its porosity is measured to be 85% by testing mercury intrusion porosimetry. Especially, some small fiber protrusions are observed on the surface of buffer layer, which are categorized and named as tip protrusions and arched protrusions. Subsequently, the influence of these fiber protrusions is investigated by quantitatively proposing their geometric models. The electric field distortion is observed at the fiber regions after finite element simulation. Under the extreme circumstances when the tip protrusions are vertical and close to the central area of air gap, the maximum electric field at tip site can reach to 28.5 kV/mm, which is 9.5 times of the breakdown threshold of air. And the maximum electric field of arched protrusions region can reach to 5.94 kV/mm, which is more moderate but still higher than the threshold. Therefore, it is demonstrated that the breakdown of air gap inner cables can be induced by the inhomogeneous fiber protrusions.

Effect of in-situ synthesized TiC particles on microstructure and mechanical properties of directed energy deposited AA2219 Al-Cu alloy

Directed energy deposition (DED) process can enable rapid and low-cost manufacturing of large-scale high-strength AA2219 Al-6.3 wt%Cu alloy components, displaying broad prospects for structural lightweighting in aerospace applications. However, a high tendency to prominent porosity defects and inhomogeneous layered microstructure are intrinsically present in DED-processed Al-Cu alloy, leading to significant performance degradation and anisotropy. Herein, we demonstrate a robust DED process to fabricate high-quality formed AA2219 alloy deposits, based on in-situ synthesized TiC-containing wires and an ultrasonic-frequency pulsed (UFP) arc. The effects of in-situ synthesized submicron-scale TiC particles (average diameter 0.7 ± 0.4 µm) in microstructural evolution and mechanical performance were comparatively investigated through multi-scale microstructural characterization and mechanical property measurement. The introduction of TiC particles into the as-deposited AA2219 component results in a homogeneous refined equiaxed microstructure with an average α-Al grain diameter of 23.4 ± 2.9 µm, and a dramatical elimination of porosity defects. After undergoing a T6 solution and aging treatment, the TiC-reinforced AA2219 deposit demonstrates excellent resistance against grain coarsening, porosity defects growth, and particle segregation. Moreover, the introduced TiC particles lead to a noticeably enhanced precipitation hardening behavior. A homogeneous precipitation microstructure of dispersed θ′-Al2Cu particles with an average diameter of 84.1 ± 34.5 nm and a high fraction of 9.8 ± 2.5 vol% was obtained in the heat-treated AA2219 deposit. Based on the as-built multiscale homogeneous microstructure, the heat-treated deposit embedded with TiC particles exhibits a synergy of unprecedented tensile strength of 501 ± 14 MPa and excellent ductility of 9.6 ± 3.3%.

Fracture mechanism of 316L/BNi-2 brazed joints using experiment and microstructure-based model

Compact components are prone to failure at brazed joints. To ensure the reliability of brazed joints, it is vital to have a comprehensive understanding of the fracture mechanism of brazed joints which can be attributed to highly inhomogeneous microstructures and individual phase mechanical properties. This study measured the stress-strain curve of brazed joint micro-zone of 316L austenitic stainless steel with the BNi-2 filler alloy by a tensile testing machine equipped with a CCD camera. The instrumented indentation technique was used to determine the flow properties of individual phases in joints considering the size effect. Representative volume element (RVE) technology was applied to simulate the mechanical behavior of brazed joints, which was in good agreement with the tested. The fracture of brazed joints can be divided into ductile fracture and brittle fracture which includes the decohesion of the interface between the boride and the austenite matrix and the fragmentation of the boride in terms of the analysis of the morphology of cross-section and fracture surface in brazed joints. According to the stress and strain distribution in the brazing micro-zone, the plastic strain localization cause decohesion, and the stress concentration along the loading direction cause boride fragmentation.

Simultaneously improved strength and ductility of low-cost Ti-Al-V-Fe alloy with TiB2 addition and thermomechanical processing

To obtain the low-cost titanium alloys with simultaneously improved strength and ductility by thermomechanical processing, 0.1 wt% of boron was added to the Ti-4Al-2.5V-1.5Fe alloy using titanium diboride (TiB2) as a boron source. The deformation mechanisms and microstructure evolution were systematically studied by comparative investigation of Ti-4Al-2.5V-1.5Fe alloys with and without boron. The results indicated that the addition of boride had a significant effect on the material parameters. Furthermore, TiB greatly improved the spheroidization and recrystallization of the alloy, and it can effectively limit grain growth during thermal exposure. Consequently, both high-temperature forging and further thermal deformation facilitated the generation and retention of the fine grain structure, dramatically improving the processibility of Ti alloys. For bare alloys, severe plastic deformation often leads to inhomogeneous microstructures and flow instability, which is harmful to mechanical integrity. In contrast, the addition of borides can significantly mitigate flow localization. In this study, boron-modified titanium alloys exhibited improved processibility and beneficial mechanical properties attributed to beneficial effects due to the addition of borides, which may enable new strategies for manufacturing high-strength titanium alloys in a more cost-effective way.

Estimation of Cooling Rate of High-Strength Thick Plate Steel during Water Quenching Based on a Dilatometric Experiment.

The microstructure and hardness along the thickness direction of a water-quenched, high-strength thick plate with a thickness of 40 mm were investigated with three specimens from the thick plate: surface, 1/4t, and 1/2t (center) thickness, and the phase transformation behavior of the thick plate according to the cooling rate was analyzed through dilatometric experiments. Finally, the cooling rate for each thickness of the thick plate was estimated by comparing the microstructure and hardness of the thick plate along with the thickness with those of the dilatometric specimens. Martensite microstructure was observed on the surface of the water-quenched thick plate due to the fast cooling rate. On the other hand, an inhomogeneous microstructure was transformed inside the thick plate due to the relatively slow cooling rate and central segregation of Mn. A small fraction of bainite was shown at 1/4t thickness. A banded microstructure with martensite and bainite resulting from Mn segregation was developed at 1/2t; that is, the full martensite microstructure was transformed in the Mn-enriched area even at a slow cooling rate due to high hardenability, but a bainite microstructure was formed in the Mn-depleted area owing to relatively low hardenability. A portion of martensite with fine cementite at the surface and 1/4t was identified as auto-tempered martensite with a Bagaryatskii orientation relationship between the ferrite matrix and cementite. The microstructure and hardness as well as dilatation were investigated at various cooling rates through a dilatometric experiment, and a continuous cooling transformation (CCT) diagram was finally presented for the thick plate. Comparing the microstructure and hardness at the surface, 1/4t, and 1/2t of the thick plate with those of dilatometric specimens cooled at various cooling rates, it was estimated that the surface of the thick plate was cooled at more than 20 °C/s, whereas the 1/4t region was cooled at approximately 5~10 °C/s during water quenching. Despite the difficulty in estimation of the cooling rate of 1/2t due to the banded structure, the cooling rate of 1/2t was estimated between 3 and 5 °C/s based on the results of an Mn-depleted zone.

A close look at temperature profiles during laser powder bed fusion using operando X-ray diffraction and finite element simulations

In laser powder bed fusion (LPBF), complex components are manufactured layer-by-layer via scanning the cross-sections of a 3D CAD model using a high intensity laser. Throughout this process, the material is exposed to temperature profiles that significantly differ from conventional manufacturing methods, and result in development of a unique and inhomogeneous microstructure and high levels of residual stresses in additively fabricated parts. The large temperature gradients and rapid cooling rates around the moving laser spot, and the overall heterogeneity of the temperature field need to be better understood in order to optimize the process parameters for increased production quality. In this study, operando X-ray diffraction (XRD) was employed to measure and compare temperature histories on the laser path under various processing conditions for Hastelloy X. Finite element thermal simulations were validated based on the acquired XRD data and then used as a supplementary tool to discuss the cooling behaviour and thermal heterogeneities across the geometry. The increase in the deposited energy density was qualitatively linked with higher temperature levels and slower cooling rates during LPBF. The melt-pool lengths showed strong sensitivity to the laser power and little variation with the scanning speed. Furthermore, even for a single set of parameters, large variations in the temperature field within the build were observed such that the cross-section edges located at higher build layers were exposed to markedly higher temperature levels.

Effect of through-thickness microstructure inhomogeneity on mechanical properties and strain hardening behavior in heavy-wall X70 pipeline steels

The ever-increasing demand for oil & gas exploration from land to subsea necessitates using higher-strength and high-ductility heavy-wall thickness pipes, which may increase the microstructural inhomogeneity along the steel plate sections, ultimately impacting the mechanical properties. In this work, the differences in microstructure and mechanical properties between the through-thickness layers of a heavy-wall ferrite/bainite (F/B) dual-phase (DP) X70 pipeline steel plate were studied. The results showed that the size of the ferrite grain and the volume fraction of bainite increased from the surface layer to the mid-thickness layer of the DP X70 pipeline steel plate. The surface and mid-thickness layers had a lower uniform elongation and higher strength and hardness. In comparison, the quarter layer had higher uniform elongation and lower strength and hardness. The refined grain size and the strong {001}<110> texture were responsible for enhanced in strength and hardness. The higher γ-fiber texture at the quarter layer favored the higher plasticity. The analysis results of strain-hardening behaviors based on the modified C-J model showed that the mid-thickness layer had a higher strain-hardening capacity at the beginning of the plastic strain, leading to deformation instability and reduced material plasticity. The surface layer maintained a high hardening exponent even at high plastic strains, which facilitated the deformation properties of the material. The results provide a basis for evaluating the influence of microstructural factors on the strength and plasticity of heavy-wall X70 pipeline steel and the coordination mechanism of micro deformation in DP steels.

Microstructural Inhomogeneity and Mechanical Properties of Ti–6.4Al–3.3Mo–1.6Zr–0.2Si Alloy Fabricated by Laser Metal Deposition

Laser metal deposition (LMD) additive manufacturing has gained growing interest in the aerospace industry. Herein, a Ti–6.4Al–3.3Mo–1.6Zr–0.2Si (TC11) titanium alloy is produced by LMD. The inhomogeneity of multiscale grain morphology and mechanical properties are systematically investigated. The results indicate that the melting pool (MP) morphology can be divided into three areas: melting pool center (MPC), melting pool boundary (MPB), and heat‐affected zone (HAZ), respectively. The widths of α laths in MPB are larger than that in HAZ and MPC, which result in a lower microhardness in MPB than that in MPC. Besides, the columnar grains are generally distributed along the deposition direction. The average widths of the α laths in the top and bottom MPC regions are about 0.58 and 0.67 μm, respectively. Correspondingly, the ultimate tensile strength and fracture elongation of the top and bottom samples are 1,053.5 MPa, 16.7%, and 1,011.5 MPa, 20.7%, respectively, which suggest the inhomogeneity of mechanical properties. The initiation fracture sites of both the top and bottom samples are presumed to be the α lath inside the MPB according to stress distribution analysis. The formation mechanisms of inhomogeneous grain structures and their influences on mechanical performance are also discussed.

Predicting the creep-rupture lifetime of a cast austenitic stainless steel using Larson-Miller and Wilshire parametric approaches

An experimental dataset of just over 100 creep tests of a cast austenitic stainless steel, CF8C-Plus, was analyzed by two temperature-compensated parametric models (Larson-Miller, Wilshire et al.) to predict long-term lifetimes as functions of temperature and stress. The dataset and associated regression analyses showed greater scatter than typically found in recent similar studies of wrought Ni-based alloys by the same two models and was attributed to the microstructural inhomogeneity of the cast stainless steel. Qualitatively, the Larson-Miller formalism showed greater lifetime prediction accuracy than the Wilshire approach, with the latter model's predictive ability being particularly degraded by the presence of two very significant outlier results. This observation suggests that the Larson-Miller approach is more robust when treating rupture-time datasets that show particularly wide experimental scatter. Despite the differences in the overall predictive ability, both models yielded similar predictions of the applied stress at which CF8C-Plus would have a creep-limited lifetime of 100,000 h when loaded below the yield point.

THE EFFECT OF ROTARY SWAGING ON THE STRUCTURE, MECHANICAL AND CORROSION PROPERTIES OF THE Mg-1.1%Zn-1.7%Dy ALLOY

In this work, the effect of rotary swaging (RS) with a deformation degree (ε) equal to 1.28 and 2.31 on the microstructure, corrosion resistance and mechanical properties of a potential medical alloy Mg-1.1%Zn-1.7%Dy was studied. It was shown that RS at ε = 1.28 leads to a grain refinement of the studied alloy by 10 times (from ~300–400 µm to ~30–40 µm). An increase in the deformation degree up to ε = 2.31 leads to the formation of an inhomogeneous microstructure with regions containing both grains ~30–40 µm in size and zones with grains ~5–10 µm in size. Grain refinement after Rs leads to an increase in resistance to electrochemical corrosion (corrosion potential increases from -1550 ± 9 mV in the quenched state to -1442 ± 23 and -1454 ± 35 mV after RS at ε = 1.28 and ε = 2.31, respectively), but does not cause a change in the current density. But the degradation rate of the alloy increases with an increase in the deformation degree up to 3.46 ± 1.06 mm/y. The structure refinement after RS at ε = 1.28 leads to a significant increase in the strength of the alloy in comparison with the quenched state (ultimate tensile strength (UTS) increases from 70 ± 13 to 273 ± 7 MPa) with a drop in ductility from 23.1 ± 5.1 to 14.0 ± 2.9%. An increase in the deformation degree up to ε = 2.31 does not lead to an increase in the strength of the alloy (UTS = 267 ± 4 MPa), but causes an increase in ductility (δ = 21.1 ± 1.6%), apparently due to texturechanges, occurring in the alloy.

Through-Thickness Inhomogeneity of Microstructures and Mechanical Properties in an As-Quenched Thin Specification High Strength NM450TP Steel Plate

The inhomogeneity of microstructures and mechanical properties in an as-quenched thin specification NM450TP wear-resistant steel plate were quantitatively investigated. The results show that the microstructures exhibit inhomogeneous distribution through the thickness and the area percentage of martensite and ferrite grains varies regularly through the thickness, and the content of ferrite on the top surface of the plate is found to be two times that of ferrite at the core location and more than that of ferrite at the bottom surface. In addition, the steel plate exhibits the obvious anisotropy of tensile properties, the tensile strength paralleling to the rolling direction is lower than that along the transverse direction while the elongation paralleling to the rolling direction is better than that along the transverse direction. The result indicates that the deformation degree of prior austenite grains during hot rolling and the content of martensite after quenching dominate the mechanical properties while the ferrite content is not the main factor affecting the plasticity. The findings provide experimental evidences and lay a theoretical foundation for analyzing the subsequent processing.

Anisotropic orientation dependent shock wave responses of monocrystalline molybdenum

Molybdenum (Mo) demonstrates excellent industrial application potentials in micro-nano devices, which are inevitably subjected to shock loads during their application under harsh service environments. This study employs molecular dynamics (MD) simulations to investigate the shock responses of Mo under high-strain loading conditions with respect to the effects of crystal orientations. The findings reveal that monocrystalline Mo, along the shock direction of [111], exhibits inhomogeneous microstructure features characterized by significantly high-density and high-temperature localized regions. Once the rarefaction wave is produced, the physical parameters, including density and lateral pressure, will gradually decrease while normal pressure retains a residual value. The us-up, Pzz-up, and Pzz-V/V0 relations along the shock loading direction of [111] show deviations from those of [001] and [110] directions, with this difference being more pronounced for Pzz-V/V0. The formation of dislocations and the magnitude of shear stress experienced within the post-shock region are strongly dependent on crystal orientations. Specifically, an elevated probability of dislocation formation was observed along the [110] direction. Moreover, the magnitude of shear stress induced by shock loading along the [001] and [110] directions can exceed that of the [111] direction when the shock velocity is 1.5 km/s. The MD simulation results can serve as a valuable supplement to the investigations of mechanical properties pertaining to Mo.

Reproducible stable critical current density in powder-in-tube (PIT) Nb3Al superconductors by multi-time rapid heating and quenching process

This paper investigated the microstructure and superconductivity of the powder-in-tube (PIT) Nb3Al short samples with different rapid heating and quenching (RHQ) treatment. Single RHQ processed Nb3Al wires showed inhomogeneous microstructure and the superconductivity were sensitive to rapid heating temperature (Tmax), showing significant fluctuation with a slight change of Tmax. Multi-time RHQ treatment was performed to homogenize the Nb3Al superconductors. The highly uniform microstructure and composition distribution were found in 5-time RHQ processed Nb3Al wires, which exhibited significantly stable and excellent Jc performance. Reproducible stable Jc results of Nb3Al wires were realized in three samples of 5-time RHQ treatment with a difference of Tmax reaching about 200 °C. Jc of the three samples fluctuated less than 20% with results of 1.1 × 105 A/cm2, 9.87 × 104 A/cm2 and 9.51 × 104 A/cm2 at 4.2 K and 12 T. The insensitivity of Jc to Tmax in 5-time RHQ processed Nb3Al samples might attribute to the highly homogeneous Nb3Al A15 phase.

Re-examination and comparison of activation volume, strain rate sensitivity, and dislocation density for coarse grain and CGP-processed UFG materials

The frequently used metallurgical parameters such as activation volume, internal stress, strain rate sensitivity, and dislocation density are identified in ultrafine-grained (UFG) materials through erudite analytical relations. It is difficult to analyze such parameters optically since the material consists of highly distorted and inhomogeneous microstructure due to the large strain imposed during the constrained groove pressing (CGP) process. Hence, transient tests like stress relaxation tests are advantageous over the optical to use. Apart from the identification of parameters in low-carbon steel materials using uniaxial loading and stress relaxation tests, the relationship between the parameters is nobly investigated in as-received and UFG structure samples produced through the CGP process. In the relationship, the exponential-power law constitutive to describe the accurate stress–strain curves, identification of mobile and forest dislocation density during strain hardening, and exponential variation between grain size and activation volume are proposed. The replenishment or exhaustion of mobile and forest dislocation density significantly affects the metallurgical parameters during uniaxial tensile loading followed by stress relaxation testing. In this experimental and analytical work, the CGP process produces a UFG material that has lower activation volume and higher stress drop, mobile dislocation density, forest dislocations density, strain rate sensitivity, and internal stress.

Failure behavior of a roller in automotive flywheel manufacturing

The failure behavior of a carburized 18CrNiMo7-6 steel roller from a roll forming mill used to manufacture automotive flywheels is investigated. Microstructural observations using optical and scanning electron microscopy are carried out, and the hardness determined using a Vickers hardness testing machine. The carburized layer is mainly comprised of fine tempered martensite, small carbides and retained austenite. The depth of the carburized layer around the roller groove is thinner than the required standard. The decrease in microhardness with increasing distance from the surface to the core is found to be due to the different carbon concentrations. However, a pronounced variation of the microhardness value is detected around the roller groove surface. This is related to the formation of an inhomogeneous microstructure during quenching after the carburizing process. The results indicate that the crack nucleates at the bottom surface of the roller and propagates along the direction vertical to the roll forming with a transgranular character.

Strength-plasticity transition mechanism after the solution treatment of GH3230 superalloy fabricated via laser powder bed fusion

Owing to their unique microstructure, GH3230 superalloys prepared using laser powder bed fusion (LPBF) exhibit high strength but low ductility, which limits their functional performance in engine combustion chambers. In this study, the process parameters were optimized to obtain LPBF GH3230 with minimal defects, and solid-solution treatment (ST) was conducted to modulate its inhomogeneous microstructure and mechanical properties. The results revealed that ST eliminated the substructure of as-printed (AP) samples and transformed nano-M23C6 into micron and submicron M6C/M12C in situ. Significant amounts of M6C/M12C promoted Orowan strengthening, but the quasi-continuous semi-coherent lattice interface between M6C/M12C and the matrix was a weak zone for cracking, resulting in reduced plasticity owing to the presence of micron carbide. The increased solid solution temperature causes the carbide to remelt, triggering a strong plastic transformation. The impact of carbide size on strength and plasticity conversion rate was more significant than that of carbide content. Final, LPBF-GH3230 samples containing micron carbides were obtained in ST below 1230 °C with an ultimate tensile strength (UTS) comparable to that of forgings. Further increase in the ST temperature to 1280 °C eliminated the carbides, a LPBF-GH3230 that fulfilled the strength standard for cast parts (647 ± 23 MPa) with an excellent elongation (39.4 ± 1.7%) was obtained. This study provides a theoretical basis for the practical application of the LPBF GH3230 superalloy in the aerospace industry and offers guidance for improving post-treatment methods to ensure high plasticity.

Electric Hot Single Point Incremental Forming Process of Ti6Al4V Alloy Sheet with Water-Cooled Forming Tool

Electric hot-assisted incremental forming is an effective technique to improve the formability of Ti6Al4V titanium alloy sheets. However, the unstable electric heat can also lead to the unacceptable accuracy and inhomogeneous microstructure. In this study, a water-cooled tool was employed to stable electric-assisted forming temperature. The research results show that the stable forming temperature can significantly improve the forming properties and maintain the consistent microstructure of Ti6Al4V sheets, and the forming force and the degree of springback for the parts also decrease with the increasing temperature. The maximum forming depth is 7.0 mm at 400 °C (forming tool temperature) compared with the forming height of 4.6 mm at room temperature. The microstructure results show that the α phase is refined, and the β phase grains are elongated. The fracture morphologies of the parts at room temperature, 300 °C and 400 °C were compared and analyzed, and the dimples increased in the size and denser at high temperature.

Spatial and directional characterization of wire and arc additive manufactured aluminum alloy using phased array ultrasonic backscattering method

Pores, grains, or textures can collectively cause microstructural inhomogeneity and anisotropy in metallic materials fabricated by additive manufacturing. In this study, a phased array ultrasonic method is developed to characterize the inhomogeneity and anisotropy of wire and arc additively manufactured components by performing both beams focusing and steering. Two backscattering features, i.e., the integrated backscattering intensity and the root mean square of the backscattering signals, are employed to quantify the microstructural inhomogeneity and anisotropy, respectively. An experimental investigation is performed using an aluminum sample fabricated by wire and arc additive manufacturing. The ultrasonic measurements, performed on wire and arc additive manufactured 2319 aluminum alloy, show that the sample is inhomogeneous and weakly anisotropic. Metallography, electron backscatter diffraction, and X-ray computed tomography are used to verify the ultrasonic results. An ultrasonic scattering model is used to identify the influence of grains on the backscattering coefficient. Compared with a wrought aluminum alloy, the complex microstructure in additively manufactured material significantly influence the backscattering coefficient, and the presence of pores cannot be neglected in ultrasonic-based nondestructive evaluation for wire and arc additive manufactured metals.