Horizontal Samples Research Articles

Anisotropy of mechanical property and corrosion behavior of M2052 alloy fabricated by selectively laser melting

M2052 (Mn-20Cu-5Ni-2Fe, at%) alloy is a high-damping alloy with excellent comprehensive properties, widely used in vibration and noise reduction applications. Selective Laser Melting (SLM) technology can overcome the limitations of traditional processes and efficiently and accurately manufacture complex parts. In this study, M2052 alloy specimens were fabricated using SLM in horizontal (H0 samples), inclined (I45 samples), and vertical (V90 samples) directions. The microstructure, tensile properties, fracture morphology, and corrosion performance of the three directions were investigated. The anisotropy of yield strength and corrosion performance among the three samples was discussed. The results show that, compared to the inclined and vertical samples, the horizontal samples exhibited the highest yield and tensile strengths, with the I45 samples having the highest elongation of 26.82 %. The anisotropy of yield strength in different directions may be related to GND density, Taylor factor, and grain size. In 3.5 wt% NaCl solution, the corrosion resistance of different planes varied in the order of H0 > I45 > V90. The anisotropy of corrosion resistance may be attributed to differences in the microstructure.

Experimental study of shielding gas concentration on mechanical properties of stainless steel alloy parts using wire and arc additive manufacturing

Wire Arc Additive Manufacturing (WAAM) is an emerging three-dimensional fabrication technology that enables higher deposition rate, material savings, and near net-shape. In this study, various shielding gas concentration (SGC) of argon (Ar) and carbon-di-oxide (CO2) was employed to fabricate 316L using Cold Metal Transfer (CMT) WAAM process. Microstructure characteristics and mechanical properties of thick-walled parts were studied. Microstructure studies show a combination of columnar and equiaxed grains in various regions. Microhardness results exhibit the uneven distribution of hardness value from bottom to top region along the building direction and the values are ranging between185 and 240 HV. Tensile studies indicates the both horizontal and vertical direction samples secures the higher ultimate tensile strength (UTS), yield strength (YS) and elongation (EL) values and confirmed the isotropic properties. Fractography studies prove ductile fracture with the evidence of dimples and enough plastic deformation. From the experimental results, the SGC-2 possesses finer solidification structure and higher mechanical properties than the other samples. The as-fabricated WAAM parts possess higher mechanical properties than the 316L parts fabricated via casting and wrought parts.

Mechanical, tribological, and corrosion behavior of laser powder-bed fusion 316L stainless steel parts: Effect of build orientation

In this study, 316L stainless steel Laser Powder Bed Fusion (LPBF) samples were manufactured under three different building orientations (0°, 45°, and 90°). Mechanical, microstructural, tribological and corrosion resistance properties were analyzed for all samples. The results demonstrate that the build orientation significantly influences the microstructure, resulting in variations in grain size, texture and defect distribution. Specifically, 0° (Horizontal) samples exhibited excellent mechanical properties, including ultimate tensile strength of 784 MPa and a hardness of 292 HV, while the vertical (90°) samples showed enhanced wear resistance, characterized by reduction in the coefficient of friction. Corrosion resistance was found to be highest in the 0° samples, with a corrosion current density of 0.650 μA/cm2, compared to 1.580 μA/cm2 in the 90° samples. The results from this study show the non-linear effects of build orientation for certain properties and indicates that individual studies are not sufficient to predict the performance of LPBF parts. Therefore, combined studies are required for orientation-based optimization of the mechanical, tribological and corrosion properties of LPBF parts. This study offers valuable insights into the relationship between build orientation and material properties, providing a pathway to tailor the properties of LPBF parts for specific applications.

An investigation on the wear properties of the photocurable components produced by additive manufacturing for dentistry applications: Combined influences of UV exposure time, building direction, and sliding loads

AbstractAdditive manufacturing (AM) of polymers is a highly versatile technology that can be applied to many independent sectors like automotive, aviation, medicine, and dentistry. Since it has great potential for rapid prototyping, clean‐process concepts, and the ability to produce complex shapes, the layer‐by‐layer printing method is one of the most promising alternatives for future industrial production efforts. In that sense, different from the previous studies, this work aims to elucidate the friction and wear properties of the special dental samples manufactured via photopolymerization‐based AM technology according to both for printing parameters, and dry sliding test variables. Also, this is the first initiation to examine the combined influences of the UV exposure time, building direction, and sliding force on the surface roughness, hardness, friction coefficient, wear rate, and main plastic damage mechanism of the printed samples. The results showed that the maximum average hardness value was detected as 89.8 Shore D for vertically built samples printed with 8 s exposure time. In addition, vertically printed samples exhibited better wear resistance than the horizontal samples and the rising exposure time generally affected affirmatively the hardness levels of the samples. The lowest volume loss of 78 mm3 belonged to the vertical sample at 5 N. Further, increasing test force levels caused a decrease in the friction coefficient results and triggered the volume loss increase in the samples. Among all samples, the calculated friction coefficient values changed between 0.3 and 0.87. On the other side, scanning electron microscopy (SEM), and energy‐dispersive spectroscopy (EDS) analyses pointed out that ascending exposure times led to the altering contact surface matchings determining the final volume loss outcomes.Highlights To obtain better surface quality, vertical printing was a useful option. Horizontally printed samples exhibited higher friction coefficients. Curing time positively impacted the wear resistance for both orientations. Grooves and debris parts were observed on surfaces with low exposure times.

Microstructural Analysis and Preliminary Wear Assessment of Wire Arc Additive Manufactured AA 5083 Aluminum Alloy for Lightweight Structures

The proliferation of Wire Arc Additive Manufacturing (WAAM) has significantly enhanced the production capabilities for lightweight and structurally robust components. This study investigates the microstructural characteristics, tensile properties, and preliminary wear performance of AA 5083 aluminum alloy processed via WAAM, focusing on applications for lightweight structures. Using SEM and XRD, microstructural changes during the WAAM process are analyzed, and tensile testing evaluates the mechanical properties, including ultimate tensile strength (UTS) and elongation. The results reveal that the microstructure consists of α-Al and β-(Al5Mg8) phases, with the Al5Mg8 phase distributed along grain boundaries and within grains. Notably, the grain size in the Y-direction (building direction) is larger than in the X-direction (deposition direction) due to temperature variations during processing. Tensile testing shows that horizontal samples (X-direction) have a UTS of 295 ± 5 MPa and elongation of 20.08 ± 0.8%, while vertical samples (Y-direction) have a UTS of 267 ± 10 MPa and elongation of 16.43 ± 2.1%. This results in an anisotropy of 9.4% in tensile strength, reflecting the differences in mechanical properties between the two directions. The WAAM AA 5083 aluminum part exhibits a maximum wear rate of 5.22 × 10⁻³ mm³/m and a coefficient of friction of 0.52 at a load of 3.5 kg and 450 rpm. Under these conditions, deep grooves, layer separation, and load-induced deformation are observed. The primary wear mechanisms include delamination, adhesion, and abrasion. Hardness levels are consistent in the X-direction and show minimal variance in the Y-direction, with an average hardness of 89.4 ± 5.14 HV0.5. The study demonstrates that WAAM-produced AA 5083 aluminum alloy, with an anisotropy below 10%, is suitable for real-time lightweight structures, offering effective performance in engineering applications such as aerospace and automotive industries. Future research should focus on further quantifying wear behavior and optimizing processing conditions to enhance material performance for specific applications.

An experimental study on the influence of pressure on permeability and seismic velocity in the Montserrat geothermal field (West Indies)

Volcanic regions are prime areas for harnessing geothermal energy. However, the geological complexity of these regimes can hinder the efficient exploitation of this renewable resource. As useful as geophysical surveys are in understanding the subsurface, models can be unconstrained due to the lack of realisitic data. Here, we present the results of a new laboratory study measuring permeability and P-wave velocity on altered lavas, volcaniclastic sediments and limestones samples obtained from three cores retrieved from the MON-3 well, drilled in the Montserrat geothermal field. By measuring these parameters at increasing effective pressure varying from 10 to 70 MPa, we found permeability stress senstivity factors varying from 0.006 to 0.122 MPa−1 and increases in P- wave velocity between 2 and 20 %. The highest permeability stress senstivity factor and largest increase in P-wave velocity found in altered lavas were interpreted to be as a result of the easy closure and deformation of slit shaped microfractures and smectite clays characteristic of low bulk modulus. Conversely, lowest permeability stress senstivity factors and smallest increases in P-wave velocity found in volcaniclastic sediments, were coincident with intergranular pore geometries and higher bulk modulus minerals such as quartz and illite-smectite that may enhance the rigidity of the rock. Additionally, by measuring permeability and P-wave velocity on samples cored perpendicular (vertical) and parallel (horizontal) to the axis of the core, we found higher permeability senstivity factors (0.001–0.05 MPa−1 higher) and P-wave velocity increases (1–4 % higher) on horizontal samples, which is consistent with the preferential closure of horizontally oriented pore spaces. From this experimental study, we provide implications for enhancing geothermal energy recovery in Montserrat. Overall, our findings can be utilized to help improve on geophysical and numerical models of volcanic geothermal regimes.

Microstructure and mechanical properties of low cost co-free high strength steel fabricated by plasma arc-based directed energy deposition

Arc-based directed energy deposition (DED) is characterized by high efficiency and excellent manufacturing flexibility, making it a promising choice for fabricating large structural components. High power density plasma arc-based directed energy deposition (PA-DED) was employed to fabricate high strength steel (HSS) component with a new Co-free welding wire. The microstructure and mechanical properties of the component were investigated in detail. The results showed that the matrix microstructure consisted mainly of martensite and ferrite. Austenite was observed in the bottom and middle samples, and the bottom sample exhibited the highest austenite content. All the samples in different regions exhibited a pronounced {100} 〈001〉 cube texture. The vertical samples had worse tensile properties than horizontal samples, which would be contributed to the interlayer bands and preferred orientation. The horizontal-middle samples demonstrated the highest tensile strength (UTS: 1207.8 ± 14 MPa, EL: 15.91 ± 1.03%). All deposited samples showed strong plastic deformation characteristics, illustrating that the new Co-free HSS components manufactured by PA-DED might replace conventional high-alloy HSS components for industrial applications.

High-Performance 2319 Aluminum Alloy via CMT-WAAM: Microstructure, Porosity, and Mechanical Properties

The process of cold metal transfer (CMT) wire arc additive manufacturing (WAAM) for 2319 aluminum alloy was studied. The research investigated the coarse and fine equiaxed grain bands and porosity of the 2319 alloy after solution aging treatment, with a focus on the mechanical properties and deformation behavior of the aluminum alloy at different positions and orientations. Pores and coarse second phases mainly appeared at grain boundaries but were also observed within coarse equiaxed grains. The yield strength of the top horizontal samples reached 325.5 MPa, one of the highest yield strengths reported for 2319 aluminum alloy in the literature. The coarse brittle second phases at grain boundaries were the main crack sources during the failure process of the samples. In the fine equiaxed grain layer, cracks propagated along the grain boundaries connected to the second phases, and the presence of pores accelerated crack propagation; in the coarse equiaxed grain layer, cracks directly penetrated through the grains.

Diffusive Leakage of scCO2 in Shaly Caprocks: Effect of Geochemical Reactivity and Anisotropy

Summary Supercritical carbon dioxide (scCO2) trapping mechanisms within carbon geostorage (CGS) primarily hinge on the upper caprock system, with shales being favored for their fine-grained nature and geological abundance. Experimental assessments of CO2 reactivity in brine-saturated shales reveal microstructural changes, raising concerns about long-term CO2 leakage risks. Existing models of scCO2 transport through caprocks lack consideration for shale anisotropy. This study addresses these gaps by investigating the diffusive properties and propagation of geochemical reactivity in shaly caprocks, accounting for anisotropy. Horizontal and vertical core samples from three shale formations with varying petrophysical characteristics underwent mineralogical, total organic carbon (TOC), porosity, and velocity measurements. scCO2 treatment for up to 3 weeks at 150°F and 3,000 psi was conducted. The propagation of geochemical reactivity was monitored by multiple surface X-ray fluorescence (XRF) measurements and fine polishing. A nuclear magnetic resonance (NMR)-based H2O-D2O fluid exchange protocol was used to quantify effective diffusivities and tortuosities parallel and perpendicular to bedding. Results indicate preferential surface reactivity toward carbonate minerals; however, the apparent reaction diffusivity of the shaly caprock is notably slow (~10−15 m2/s). This aligns with previous experimental and reactive transport modeling studies, emphasizing long timescales for carbonate dissolution reactions to influence shale caprock properties. Shale-effective diffusivities display anisotropy increasing with clay content, where diffusivities parallel to bedding exceed those perpendicular by at least three times. Faster horizontal diffusion in shaly confining zones should be considered when estimating diffusive leakage along faults penetrating these zones, a significant risk in CGS. Post-scCO2 treatment, diffusivity changes vary among samples, increasing within the same order of magnitude in the clay-rich sample. Nonsteady-state modeling of scCO2 diffusion suggests limited caprock penetration over 100 years, with a minimal increase from 5 m to 7 m post-scCO2 treatment for the clay-rich sample. This study extends existing literature observations on the slow molecular diffusion of scCO2 within shaly caprocks, integrating the roles of geochemical reactions and shale anisotropy under the examined conditions.

Microscopic deformation mechanism and characteristics of carbonaceous slate during the creep process

Carbonaceous slate exhibits a significant creep deformation that seriously affects the construction and operation of underground projects. To investigate the microstructural changes characteristics and reveal the microscopic deformation mechanism of the carbonaceous slate during the creep process, multiple methods were performed, including the triaxial creep test, SEM and MIP. The following conclusions were drawn: The rock samples underwent three stages during the creep test: microporosity closure at a low-stress level, material densification at an intermediate stress level, and microcracks emerging and expanding to failure at the high stress. The creep deformation was particularly significant in the first and third processes. The lamellar particles are compressed or bent under stress in parallel and vertical directions, showing the anisotropic properties of deformation. The deformation of the rock sample is related to the angle between the bedding and the orientation of major principal stress, and the effect of the anisotropy decreases with the increased stress level. The sprouting and expansion of microfractures occur at high-stress levels, showing pressure dissolution of mineral particles, migration of very fine particles, and cement damage between lamellar particles. Finally, the horizontal samples formed a combined rupture surface composed of the laminar surface and the fracture surface intersecting it, showing brittle damage, while the vertical samples formed a fracture surface parallel to the laminar surface, showing a ductile damage pattern. Those results could provide the basis for a further understanding of the mechanical properties of carbonaceous slate and the improvement of its creep model and parameters. It was significant for the stability analysis and deformation prediction of engineering structures using numerical simulation.

The mechanical properties and microstructural evolution of 14Ni3Cr3Mo1MnTiAl high strength steel fabricated by WAAM

A self-developed high strength steel (14Ni3Cr3Mo1MnTiAl HSS) was used to manufacture a thin-walled structure by wire + arc additive manufacturing, the microstructural evolution and the anisotropy of mechanical properties were investigated. The tensile properties and impact toughness at room temperature, −20 °C and −40 °C were compared and discussed in detail. According to the results of OM and SEM, the main microstructure of WAAM-ed 14Ni3Cr3Mo1MnTiAl HSS was martensite and ferrite, and numerous Ni3Ti IMCs existed in the matrix. Reversed austenite only existed in the bottom and middle samples, and there was a K-S orientation relationship in reversed austenite and martensite/ferrite. The formation of reverted austenite could be attributed to repeated thermal cycles and high content of Ni, providing beneficial environment and condition for the formation of reverted austenite. Low temperature could increase the strength of vertical samples, while it had a negative effect on plastic and had little effect on the strength of horizontal samples. Differently, the impact toughness hardly decreased at −20 °C, while it had significant decrease at −40 °C. The anisotropy of tensile properties was attributed to the weak bonding of interlayer, phase content, the size of martensite packet/lath, and the size of Ni3Ti IMCs. Columnar crystals were one of the key factors leading to the low impact toughness of horizontal samples. The impact direction was parallel to the growth direction of columnar crystals, and the crack was prone to propagate along the boundaries of columnar crystals.

Experimental investigation of nonuniform PV soiling

Photovoltaic (PV) module soiling, i.e., the accumulation of dust on PV module surfaces, poses several challenges to PV system performance. Among these challenges, the nonuniform deposition of soiling across the module surface has received scarce attention. Soiling is directly associated with an overall performance loss, but can also potentially give rise to localised hotspots that can lead to long-term PV module failure. Therefore, addressing the issues arising from this nonuniformity is not only important for optimising energy production, but also for enhancing system reliability, and ensuring the long-term operation of relevant power generation systems. In this study, the impact of nonuniform soiling on PV performance is investigated experimentally by examining soil deposition on the upper surfaces of low-iron glass samples. Samples positioned at four different tilt angles were collected on a monthly basis over a one-year study period. Since the horizontal samples were found to represent the worst-case conditions, the most soiled sample at horizontal tilt was divided into four zones, each housing a single monocrystalline solar cell and examined further. The findings reveal that the soiled sample experiences an average transmittance deterioration of 13% relative to a clean sample, and a maximum (relative) spatial variation of 4% between the four zones. These optical losses affect the amount of sunlight received by the cells, resulting in a power deterioration of ∼6–7% per 5% drop in transmittance. The soiled sample experienced an average temperature rise of 2 °C, and an average power output (and efficiency) reduction of 30% relative to the clean sample, and a maximum (relative) spatial variation of 7% between the zones. The 30% average power loss measured in this nonuniform soiling case is more than double that which would be expected theoretically for a transmittance loss of 13% but from uniform soiling, so these results highlight the importance of addressing PV soiling for optimal PV performance, and of accounting for spatial soiling nonuniformity.

Investigation of tensile and fatigue properties of an austenitic stainless steel part fabricated by WAAM

Austenitic stainless steels are used in many industrial applications and the use of components produced from this material by the wire arc additive manufacturing (WAAM) method has gained interest. Since damage of metallic parts generally occurs due to fatigue, it is necessary to understand their fatigue properties. This study focused on the determination of tensile and fatigue properties of an austenitic stainless steel structure produced by WAAM. For this purpose, a medium-sized part was fabricated using 308LSi metallic wire and gas metal arc welding (GMAW) technique. Hardness tests and microstructure examinations were also performed on the part. In the tensile tests, it was found that the strength and ductility of the vertical and horizontal samples were different. However, the fatigue test results of horizontal and vertical specimens were very similar. The average fatigue limit was found to be 195 MPa, and the fatigue life of the sample reached 107 without any macro damage. As a result of the hardness tests, the average hardness was calculated as 197 HV0.5. In the microstructure studies, different ferrite formations were observed in the austenite matrix on the bottom, middle and upper zones. The changes in microstructure were mostly attributed to the exposure of multiple layers to different heating and cooling rates during WAAM.

The effect of high-intensity gamma radiation on PETG and ASA polymer-based fused deposition modelled 3D printed parts

There is growing interest in the application of 3D printing for demanding environments subject to gamma radiation in areas such as the nuclear industry and space exploration. In this work, the effect of gamma radiation on fused deposition modelled 3D printed parts composed of polyethylene terephthalate glycol (PETG) and acrylic styrene acrylonitrile (ASA) polymers was studied. Dose levels of up to 2.25 MGy were applied to the printed components, doses equivalent to over 1 year operating near spent nuclear fuel cells. Infrared spectroscopy showed the evidence of cross-linking by the formation of peaks corresponding to –OH and C–H bonds. Tensile and hardness testing was used to assess changes in mechanical properties and showed a reduction in ultimate tensile stress and maximum strain in parts made from both polymers, but with PETG retaining greater strength and ductility than ASA, especially at intermediate gamma exposure. Young’s modulus and hardness showed either modest increases or a fairly flat response with exposure. Mechanical properties were heavily dependent on the build structure, with horizontal build samples pulled parallel to the filament direction being several times stronger than vertical build samples pulled normal to the layers. Non-irradiated samples pulled parallel to the filament direction were indicative of ductile failure, with rough surfaces, distinct infill and wall regions and evidence of thinning occurring after fracture, but irradiated fracture surfaces were flatter, smoother and without local thinning, suggesting gamma radiation-induced embrittlement in the material. For samples pulled perpendicular to the filament direction, all fractures occurred between layers, creating flat fracture surfaces with no evidence of necking and indicative of brittle failure regardless of whether the samples were irradiated.

Conditional discrimination learning by pigeons: Stimulus-response chains or occasion setters?

In conditional discrimination, the conditional stimulus or sample indicates which of two choice or comparison stimuli is associated with a reinforcer. Two hypotheses have been proposed concerning the role of the sample stimulus. According to Hull (1952), the sample and the response to the correct comparison form a stimulus-response chain. According to Skinner (1938), however, the sample serves as an occasion setter, setting the occasion for the choice of the correct comparison stimulus. In a conditional discrimination, if the sample stimulus forms part of a stimulus-response chain, then presenting the sample in the absence of the comparison stimuli should weaken the association. If the sample serves as an occasion setter, however, presenting the sample alone should not weaken its occasion-setting ability. In two experiments we tested these predictions. In Experiment 1, following conditional discrimination training with vertical and horizontal line samples and red and green comparison stimuli, we found that the presentation of the samples without the comparison stimuli (followed sometimes by a reinforcer) had little effect on conditional discrimination accuracy. In Experiment 2, two different houselights served as samples. When we presented the samples without comparison stimuli and without the reinforcers we found similar results. The results support the hypothesis that in conditional discrimination, the samples serve as occasion setters. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Fatigue and anisotropic behavior of wire-arc additive manufactured TC17 titanium alloy

Wire-arc additive manufacturing (WAAM) was used in aeronautical engineering due to its low equipment cost and ability to create complex shapes. However, the fatigue behavior of WAAM titanium alloy, specifically for low cycle fatigue (LCF), was poorly studied. This paper investigated the microstructure and mechanical behavior of WAAM TC17 in both vertical and horizontal orientations. Fully reversed LCF tests were conducted on specimens with varying strain amplitudes from ±0.4 % to ±1.2 %. The results found that the ultimate tensile and yield strength were similar for both vertical and horizontal samples, but the elongation in the horizontal orientation was approximately 60 % lower than that in the vertical orientation. Considering the cyclic loading behavior, both vertical and horizontal samples exhibited cyclic softening characteristics at high strain amplitudes (0.8%–1.2 %). Additionally, the cyclic softening rate (CSR) of horizontal samples exhibited a higher than that of vertical samples at high strain amplitude. The LCF cracks of WAAM TC17 were initiated from the surface and internal defects of the samples. The LCF performance of the horizontal samples was found to decrease than that of vertical samples. Specifically, the fatigue performance of the horizontal samples is lower by 36.7 % compared to the vertical samples when the number of cycles is 103.

Anisotropy of soil hydraulic properties induced by repeated machinery traffic in a Typic Argiudoll of the Argentinean Pampas Region

The increase in heavy machinery traffic due to crop sequence intensification under no-tillage (NT) management can lead to soil compaction, modifying the soil pore configuration, with negative effects on water dynamics. The objective of this work is to evaluate the residual effects of repeated machinery traffic under different soil water contents on the anisotropy of soil hydraulic properties. The residual effect of repeated machinery traffic under different soil moisture conditions (partially dry, PD, and wet, W) on soil compaction was evaluated and compared with the control treatment (no traffic, T0). Field infiltration using tension disc infiltrometer was carried out, and in laboratory, in order to analyse the anisotropy of soil hydraulic properties infiltration experiments were carried out on vertical and horizontal undisturbed soil samples. No significant differences in field soil hydraulic conductivity K(h) were observed between treatments. The W treatment showed a decrease on the transmission and storage pores in the vertical direction, as compared to T0. Anisotropic behavior of soil hydraulic properties was observed for the compacted treatments. The W treatment showed an increment in the transmission porosity in the horizontal direction. In addition, the W treatment presented higher values of transmission and storage pores in the horizontal direction as compared with the vertical direction. From laboratory infiltration experiments, it was observed a strong reduction on the hydraulic conductivity measured at 0, − 3 and − 6 cm water pressure heads (K0, K3 and K6) in the vertical direction under W treatment. An anisotropic behavior for both compacted treatments was observed, with higher values of K0 in the vertical direction under the PD treatment and higher values of K0 and K3 in the horizontal direction under the W treatment. These results show that machinery traffic under wet conditions causes a disruption in soil porosity, not only with a reduction of the pore space, but also with a change in its configuration.

On the orientation-dependent mechanical properties of interstitial solute-strengthened Fe49.5Mn30Co10Cr10C0.5 high entropy alloy produced by directed energy deposition

Interstitial solute-strengthened Fe49.5Mn30Cr10Co10C0.5 (at%) high entropy alloy was additively manufactured by directed energy deposition (DED) process in this work. While the as-deposited material exhibits an excellent combination of strength and ductility, the effect of anisotropy on the mechanical performance of the DED processed component was studied in detail. The ultimate tensile strength (UTS) of the horizontal tensile sample with a main fiber texture of <111> // tensile direction (TD) went up to 1 GPa while maintaining a superb failure elongation of 36%. The vertical tensile sample, with a dominant <001> // TD texture, failed at an UTS of 750 MPa with an enhanced failure elongation of 52%. Microstructural analysis of the deformed samples showed that the horizontal samples were mainly deformed via the formation of mechanical twins, whereas the twining activity was less profound in the vertical samples. Single crystal micro-pillar compression testing revealed that the deformation mechanism complies well with the Schmid’s factor. In addition, a higher critical resolved shear stress for twining compared to slip was also confirmed in the micro-pillar compression testing.

Inelastic mechanical behaviour of an additively manufactured titanium alloy: a statistical continuum mechanics theory perspective

Statistical continuum mechanics theory was used to simulate the inelastic stress of polycrystalline materials using two-point statistics. For the experimental part, the Electron beam melting (EBM) technique (Arcam EBM Q10 additive machine) was used to fabricate cylindrical rods of Ti-6Al-4V both in horizontal and vertical directions. Electron backscatter diffraction (EBSD) technique was employed to achieve statistically reliable orientation maps of vertically and horizontally printed samples. In this study, high strain rate compression tests at six different strain rates were performed, and the stress–strain curves were generated. This work is amongst the first attempts to model the microstructure of additively manufactured hexagonal alloys under compressive loadings using the statistical continuum mechanics theory. The model is capable of simulating reasonably large microstructures (statistically representative) with a practical computational cost and accuracy, unlike numerical models that require a high computational cost. It should be noted that in additive manufacturing, due to large grains and high anisotropy, microstructures used in the simulations should be large enough to include sufficient information from the material’s structure. Therefore, using finite element models would be very challenging here. On the other hand, the statistical continuum mechanics theory uses the statistical representation of the material’s characteristics for solving the governing equations with Green’s function that enables this methodology to use more microstructure characteristic information without having a noticeable change to the computational cost. The proposed model in this study uses different microstructure characteristics such as crystal grain orientation, total slip systems, active slip systems, gain morphology, and chemical phases that are obtained from EBSD images for simulating the inelastic mechanical behavior of polycrystalline materials. Although this model simulates polycrystalline materials by considering various crystal and grain information, unlike numerical methods, it doesn’t simulate the grain interactions well and we cannot study local deformation and crack nucleation sites. This model works very well for simulating the overall behavior of material instead of each individual grain and failure analysis. This model has shown a good combination of computational cost and accuracy in which the error between the simulated and experimental strength for vertical and horizontal samples was 6.21% and 8.07%, respectively.

Experimental characteristics of 316L stainless steel thin wall processed in wire-based arc additive manufacturing process

Wire arc additive manufacturing (WAAM) is an innovative technology for the fabrication of larger metal parts with complex geometry. It has a higher deposition rate, low wastage, production efficiency, and close tolerance. In this work, 316L stainless steel parts were manufactured by cold metal transfer-based WAAM process, and the effects of microstructure and mechanical properties were investigated. Microstructure studies reveal the formation of columnar and equiaxed grain morphologies with the development of epitaxial growth along the building direction. The radiographic test confirms various defects such as pores and cracks associated with the 316L deposited part. However, the microhardness studies show a uniform distribution of hardness values. The average value of microhardness of the as-deposited part was 220 HV. Tensile studies show the horizontal samples were ultimate tensile stress (UTS): 576 MPa, yield stress (YS): 302 MPa, and elongation (EL): 35% in comparison with the vertical samples were UTS: 469 MPa, YS: 295 MPa and EL: 39% and the sample exhibits the anisotropy properties. Further, the fracture surface of the tensile sample exhibits a ductile fracture with enough dimples, voids, and plastic deformation. The result shows that fabricated WAAM stainless steel 316L parts exhibit the finer microstructure and improved mechanical properties, which is extremely better than 316L stainless steel casting, forging, and wrought counterparts.