Stress-relieved Conditions Research Articles

Parameter development and characterization of laser powder directed energy deposition of Nb – Alloy C103 for thin wall geometries

This work focuses on the parameter development and microstructural characterization of Nb-based alloy C103 for thin wall structures produced via laser powder – directed energy deposition (LP – DED). Laser power and scanning speeds were varied as part of a design of experiments to identify adequate print parameters. Combinations were evaluated for relative density, porosity, and geometrical accuracy. A combination of a laser power of 1420 W and scanning speed of 14 mm/s resulted in a relative density >99%, exhibited a consistent weld bead profile and was used for further microstructural evaluation. A mix of optical and scanning electron microscopy (SEM) revealed small, slightly elongated grains along the edges and large epitaxial grains in the central region along the Build – Transverse view. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis revealed Hf rich columnar cells in the center that transition into an evenly spaced cellular structure towards the edges of the built sample. Electron backscatter diffraction (EBSD) scans show a sharp [001] texture when looking at the cross section of the sample along the build direction. The Build – Scan view revealed a zig – zag pattern that follows the back – and – forth deposition strategy that was used. Finally, microhardness measurements were taken in the as – built (AB) and stress relieved (SR) conditions to baseline preliminary mechanical properties. The AB condition exhibited a large amount of scatter in the data and averages up to 11% larger than the SR condition. The reduction in scatter upon applying the SR cycle are indicative of a large concertation of dislocations present in the AB condition.

Fretting wear behavior on LPBF processed AlSi10Mg alloy for different heat treatment conditions

To widen the industrial application of additively manufactured (AM) parts, the study of fretting wear behavior is essential, as it ensures the safety and reliability that drive innovation in design and materials. This study explores the fretting wear behavior of the as-built and heat-treated state of AlSi10Mg alloy fabricated, viz., laser powder bed fusion (LPBF). Initially, the as-built and T5, T6, and stress-relieved (SR) heat-treated samples were examined using scanning electron microscopy (SEM) to gain insights into the microstructural changes. The as-built samples exhibited a higher hardness level (135 HV) primarily due to the presence of very fine microstructure of the α-Al cellular matrix with embedded Si. The α-Al cellular structure dissolved with various heat treatments, and Si particles coarsened. The hardness decreased to 85, 79, and 67 HV for the T5, T6, and SR conditions, respectively. Subsequently, fretting tests were conducted on the samples, applying various normal loads of 10, 50, and 100 N. Further, the samples were characterized by the coefficient of friction (COF), worn surface morphology, and wear volume loss. The investigation showed that the as-built material showed less wear volume loss under all loading conditions than the heat-treated conditions. Furthermore, the T5 heat treated sample had a lower wear volume when compared to the T6 and SR heat-treated samples. The heat-treated sample exhibits compressive stress, whereas the LPBF processed, the as-built sample shows tensile stress.

CORROSION EVALUATION OF LPBF-MANUFACTURED DUPLEX STAINLESS STEEL

In this study, the effect of as built and heat-treated additively manufactured 2507 super duplex stainless steel (SDSS) on electrochemical corrosion performance was examined. The corrosion was studied by Tafel polarization and electrochemical impedance spectroscopy (EIS) methods in a 3.5% NaCl solution. For this purpose, the as-built and heat-treated printed samples (solution annealed and stress-relieved) were examined by LOM/SEM and X-ray diffraction to evaluate the phase changes of steel at different processing stages. The correlation between corrosion resistance, structure, and heat treatment was assessed. As a result of the very fast cooling rate of the LPBF process, SDSS reveals ferrite as the major phase in the printed samples. To enhance the corrosion resistance of LPBF-produced duplex stainless steel, it's crucial to balance its two-phase structure and minimize residual stresses. The ferrite grains are elongated in the build direction, with some austenite precipitation along the grain boundaries or as Widmanstatten laths. The stress-relieved and as-printed SDSS exhibits reduced corrosion characteristics by around 20% compared to the solution-annealed SDSS, according to anodic polarization curves. Based on EIS results, the solution-annealed SDSS revealed an almost double increase in corrosion resistance (based on charge transfer resistance values) compared to the as-printed and stress-relieved conditions.

An experimental investigation of selective laser melting parameters effects on ferromagnetic properties of pure iron in both the as-built and annealed conditions

In this study, the effect of selective laser melting (SLM) parameters on the magnetic properties of pure iron has been experimentally extracted both in the as-built (A-Built) and stress-relieved (H-Treat) conditions, and the optimum levels of the parameters have been determined for optimum magnetic properties. The SLM process parameters include laser power, scanning speed, and hatch spacing, and the design of experiments was done by the Taguchi method. After manufacturing and preparing the specimens, their hysteresis curves were measured using vibrating-sample magnetometer (VSM), and the magnetic properties of the SLMed pure iron were calculated. Signal-to-noise analysis was used to determine the optimal levels of parameters for achieving the best magnetic properties. For samples’ permeability and coercivity, the best possible regression equations were extracted, and SOBOL sensitivity analysis was used to determine the most contributing input variable to the outputs. The results indicate that the laser power parameter has the most significant impact on the magnetic properties of the produced parts. Two of samples were annealed at 820 °C for 1 h, and then magnetic properties were remeasured. Although there was not a significant change in permeability, and magnetization saturation of the samples, coercive force has decreased approximately 60 %. This reduction in annealing is desirable for some AC electrical devices.

A Comparative Investigation of Duplex and Super Duplex Stainless Steels Processed through Laser Powder Bed Fusion

The aim of this paper was to compare duplex (DSS) and super duplex stainless steel processed by laser powder bed fusion (LPBF) based on the process parameters and microstructure–nanomechanical property relationships. Each alloy was investigated with respect to its feedstock powder characteristics. Optimum process parameters including scanning speed, laser power, beam diameter, laser energy density, and layer thickness were defined for each alloy, and near-fully dense parts (>99.9%) were produced. Microstructural analysis was performed via optical (OM), scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The samples were subjected to stress relief and high-temperature annealing. EBSD revealed the crystallographic orientation and quantified the phases in the as-built and annealed sample conditions. The as-built samples revealed a fully ferritic microstructure with a small amount of grain boundary austenite in the SDSS microstructure. High-temperature solution annealing resulted in the desired duplex microstructure for both alloys. There were no secondary phases present in the microstructure after both heat treatments. Nanoindentation generated nanomechanical (modulus) mapping grids and quantified the nanomechanical (both hardness and modulus) response; plasticity and stress relief were also assessed in all three conditions (as-built, stress-relieved, and annealed) in both DSS and SDSS. Austenite formation in the annealed condition contributed to lower hardness levels (~4.3–4.8 Gpa) and higher plastic deformation compared to the as-built (~5.7–6.3 Gpa) and stress-relieved conditions (~4.8–5.8 Gpa) for both alloys. SDSS featured a ~60% austenite volume fraction in its annealed and quenched microstructure, attributed to its higher nickel and nitrogen contents compared to DSS, which exhibited a ~30% austenite volume fraction.

Effect of high temperature annealing on the microstructure evolution and hardness behavior of the Inconel 625 superalloy additively manufactured by laser powder bed fusion

Additive manufacturing of Inconel 625 components attracts great interest due to its ability to produce parts with complex geometries that are needed for high-temperature applications in the aerospace, energy, automotive and chemical industries. To take full advantage of the potential of additive manufacturing, an in-depth understanding of the effects of prolonged high-temperature annealing on microstructure and hardness evolution is needed. Previous research in this field has mainly focused on a limited range of temperature and time. This study aims to determine the effect of prolonged high-temperature annealing on the evolution of intermetallic phases and carbides, as well as changes in the dislocation substructure of Inconel 625 superalloy additively manufactured by laser powder bed fusion subjected to stress relief annealing and subsequent isothermal annealing at a temperature up to 800 °C for 5–500 h. The microstructure development is correlated with hardness behaviour. It is determined that the microstructure evolution proceeds in four stages with temperature and time increase. In the initial stress-relieved condition, a cellular microstructure with nano-sized precipitates of the Laves phase and NbC carbides at the cell walls occurs, and hardness is equal to 300 HV10. In the 1st stage of the microstructure evolution, the γ'' phase particles precipitate on the cell walls, which results in hardening up to 383 HV10 in the specimen annealed at 700 °C for 5 h. The 2nd stage involves the precipitation of the γ'' phase both on the cell walls and inside the cells, as well as the formation of dislocation networks, which contribute to the softening effect and hardness drop to 319 HV10. In the 3rd stage, at temperature 700 and 800 °C, the δ phase, M23C6 carbides, and the Laves phase precipitate and grow, and the subgrain boundaries are formed. The hardness is in the range of 340–350 HV10 and is higher than in the 2nd stage. In the 4th stage, as the annealing time is increased at a temperature of 800 °C, the δ phase and M23C6 carbides coagulate, and the Laves phase particles spheroidize or partially dissolve. Very intense precipitation and growth of the hard δ phase particles provide an increase in hardness to 402 HV10. As a result of systematic studies, the various strengthening and softening mechanisms acting during high-temperature annealing are determined.Graphical abstract

The effect of thermal history on the additively manufactured AlSi10Mg alloy response to ion irradiation

Aluminum alloys, mainly from the 5xxx and 6xxx families, are used extensively in research reactors due to their suitable properties. However, alloys common in nuclear applications are not yet suitable for Additive Manufacturing (AM). The alloy AlSi10Mg has good engineering properties and is the most used and investigated AM Al-alloy. In this work, stress relieved (SR) samples of AM AlSi10Mg have been compared to samples that underwent a subsequent heat treatment at 500°C (SHT), producing two distinctly different microstructures. The SHT samples contain larger grains with a cleaner matrix and coarser silicon particles compared to the SR samples. Samples with the two microstructures were irradiated using silicon ions up to damage of ∼20 dpa at a depth of about 1 µm. To compare the response of both conditions to irradiation, properties were measured using nano-indentation and transient grating spectroscopy (TGS). Microstructure was characterized using TEM. Results show that the SHT condition is much more sensitive to irradiation, compared to SR. Irradiation caused thermal diffusivity to decrease by ∼5% in the SR condition and by more than 50% in the SHT condition. Hardness increased by 12 and 24% in the SR and SHT conditions, respectively. Also, the void number density was significantly larger in the SHT condition. No change was observed in young's modulus. The lower sensitivity of the SR condition is attributed to a higher sink density present in the initial microstructure, resulting in overall less irradiation damage retained in the material after irradiation. The explanation offered for the major drop in thermal diffusivity observed only in the SHT condition is the large size of the silicon particles, which increases their instability during irradiation, causing them to partly dissolve and release atomic silicon into the matrix around them. These silicon atoms are effective electron and phonon scatter centers. The findings of this work show that the pre-irradiated microstructure of AM AlSi10Mg has a crucial role in the material's performance in nuclear reactor core conditions. Careful thought and care need to be implemented to the heat treatment applied to an as-built part.

Ageing response and strengthening mechanisms in a new Al-Mn-Ni-Cu-Zr alloy designed for laser powder bed fusion

Aluminum alloys designed for laser powder bed fusion (L-PBF) often show a bimodal grain structure and a strong out-of-equilibrium character with heterogeneities developing at scales ranging from the melt pool, i.e. several hundred microns, down to sub-nanometer. When subjected to post-fabrication heat treatments, microstructural evolutions arise at all scales. Herein are established the relationships between microstructure and mechanical properties at room temperature of a novel Al-4Mn-3Ni-2Cu-1Zr alloy, designed for L-PBF and subjected to direct ageing. On the basis of a multiscale microstructural study using scanning-electron microscopy (SEM), automated orientation mapping in the transmission-electron microscope (TEM-ACOM), atom probe tomography (APT), and synchrotron small-angle X-ray scattering (SAXS), we discuss and weigh the role of multiple strengthening mechanisms to the high strength of the material. In the stress-relieved conditions (300 °C/4 h), the yield strength is about 320 MPa and solid solution strengthening accounts for nearly two third of the yield strength (∼200 MPa) thanks to a very high content of Mn retained in solid solution (> 1.5 at.%) and, to a lesser extent, grain boundary strengthening. After ageing at 400 °C/1 h, the yield strength reaches 410 MPa. The additional contribution is brought by precipitation strengthening by L12-ordered Al3Zr, and to a lesser extent, Mn-rich precipitates. The composite effect due to the large fraction of relatively fine (< 1 μm) intermetallic particles (∼20%) is highlighted and cannot be neglected. This work provides guidelines to further optimize the mechanical properties and thermal stability of Al-alloys designed for L-PBF.

Characterisation of the Tensile and Metallurgical Properties of Laser Powder Bed Fusion-Produced Ti-6Al-4V ELI in the Duplex Annealed and Dry Electropolished Conditions

Metal additive manufacturing is becoming a popular manufacturing process in industries requiring geometrically complex components, part consolidation, and reductions in material waste. Metals manufactured via additive manufacturing processes such as laser powder bed fusion typically exhibit process-induced defects, material inhomogeneities, and anisotropy in terms of mechanical properties. Post-processing techniques such as heat treatments and surface finishing have been touted as approaches for improving these materials. Although various post-processing techniques have been proposed, the optimal post-processing route remains an active area of research. This research investigates Ti-6Al-4V ELI produced using laser powder bed fusion and post-processed via different routes. The materials in the stress-relieved and duplex annealed material conditions as well as dry electropolished and machined surface conditions were characterised. The duplex annealed Ti-6Al-4V ELI material showed improvements in ductility but at reduced strength when compared with the material in the stress-relieved condition. The microstructure of the duplex annealed material shows little evidence of process-induced defects and features and consists primarily of elongated and acicular α in a lamellar structure with intergranular β and exhibits uniform microhardness throughout the material. A reduced surface roughness due to surface finishing resulted in an improved reduction in area. This research highlights the effects of post-processing treatments and their ability to improve the properties of laser powder bed fusion-produced Ti-6Al-4V ELI.

Fatigue response of a cast Al-Cu-Mg-Ag-TiB2 (A205) alloy: Stress relieved and aged

The purpose of this study is to assess the influence of heat treatment on the fatigue behavior of cast A205 alloy (i.e., Al-Cu-Mg-Ag-TiB2 nanocomposite). To do so, A205 samples were heat-treated and divided into two categories (i) stress-relieved (SR) and (ii) T7 stabilizing over-aged. This research delves further into the microstructure, mechanical properties, and fatigue performance of A205 alloy in SR and T7 heat-treated (i.e., T7 aged) conditions. After production and post-heat treatments, the samples underwent force-controlled fatigue experiments, tensile and depth-sensing indentation testing, and advanced microstructural characterizations (using electron backscattered diffraction and transmission electron microscopy). Microstructural characterization revealed exceptionally equiaxed, texture-free microstructure with uniform grain distribution and the existence of Al2Cu precipitates and TiB2 particles. The T7 heat treatment did not change grain size significantly (grain size: 46.4 ± 13.5 µm for SR and 48.5 ± 13.7 µm for T7 material). The T7 heat treatment was found to be very effective in improving the fatigue resistance of A205. The higher fatigue resistance of cast T7 material is attributed to the accelerated precipitation of Al2Cu along with different habit planes. The results of this study offer a critical understanding for choosing the optimum heat treatment parameters to control the fatigue behavior of cast A205, which is crucial considering their applications in the aerospace industry.

The Corrosion Behaviour of Additively Manufactured AlSi10Mg Parts Compared to Traditional Al Alloys

Additive manufacturing of metal parts in the motorsport industry is becoming a decisive technology for producing lightweight and rigid parts, with increasing applications as the costs decrease. Among the available metal alloys, AlSi10Mg is one of the most widely used. In this paper, the corrosion resistance of additively manufactured AlSi10Mg is compared with that of other traditionally manufactured aluminium alloys widespread in the automotive industry. Several potentially corrosive agents, typical of vehicle applications, were used: salty water, motor oil, suspension oil, cooling fluid and gasoline. Corrosion tests were conducted at both room temperature and 90 °C. The effects of heat and surface treatments were evaluated separately. The samples were visually inspected and weighed to evaluate the corrosion rate with the aid of SEM and EDS analysis. Additively manufactured AlSi10Mg generally showed better corrosion resistance in the stress-relieved condition as compared to the T6-treated state, with slightly better results for the polished samples. Motor oil, suspension oil, cooling fluid and gasoline did not significantly corrode the specimens, except for the T6-treated AlSi10Mg samples at 90 °C. However, the corrosion rate was always higher than traditionally manufactured aluminium alloys tested for comparison.

The effect of heat treatment on fatigue response of laser powder bed fused Al-Cu-Mg-Ag-TiB2 (A20X) alloy

The paper aims at assessing the effect of heat treatment on the fatigue behavior of a novel laser-powder bed fused (L-PBF) Al-Cu-Mg-Ag-TiB2 composite, otherwise known as A20X alloy. Heat treatments, (i) stress relieving, and (ii) T7 over-aging and stabilizing, were performed on L-PBF A20X materials, followed by advanced microstructural characterizations, mechanical property measurements (utilizing tensile and depth-sensing indentation testing), and force-controlled fatigue testing. Microstructural assessments revealed the ultra-fine and fine equiaxed grain structure of the L-PBF stress-relieved and aged A20X materials. Mechanical properties (yield stress, ultimate strength, and nano-hardness quantities) of the aged material were recorded as higher than the stress-relieved counter materials. By the same token, the aged material showed better low-cycle and high-cycle fatigue performance and higher fatigue strength relative to the stress-relieved conditions. Based on detailed fractography assessments, the life-limiting fatigue failures of the studied materials (stress relived and T7 aged) were primarily governed by sub-surface L-PBF-induced volumetric defects such as pores and/or lack of fusion. The findings of this study present useful information on the role/mechanism of inevitable process-induced interior defects on fatigue behavior of the Al-Cu-Mg-Ag-TiB2 composites and the effect of post-processing (i.e., aging in this research) on fatigue behavior, which is of great significance for the high-demanding and critical applications of lightweight high-strength L-PBF Al-Cu-Mg-Ag-TiB2 composites in the space and aviation sectors.

Experimental determination of cyclically stabilized material properties of the Mo-based alloy MHC in stress-relieved condition from room temperature to 1400 °C

The aim of the current study was the determination of the time-dependent visco-plastic material behavior of the molybdenum alloy MHC (Molybdenum-Hafnium-Carbon) in stress-relieved condition with cyclic strain-controlled low cycle fatigue experiments at room temperature, 800 °C and 1400 °C. To ensure high data quality, a servohydraulic testing machine modified with a vacuum chamber was utilized to avoid material oxidation. The long-time strain-controlled experiments were conducted with a laser extensometer with high accuracy up to the highest applied test temperature of 1400 °C. The determined data were appropriate to generate cyclic stress-strain curves, strain-Wöhler curves, and their descriptive parameters. Furthermore, the strain rate dependency of the cyclic stress response and the stress relaxation behavior of the cyclically stabilized material were also investigated at the mentioned temperatures. The current study indicates that MHC in stress-relieved condition has a softening ability during cyclic loading, especially at 800 °C and 1400 °C. The strain rate sensitivity of the stress amplitude for the case of cyclic stabilization shows similar behavior as described in the literature for the case of monotonously increasing loading conditions, with a minimum at 800 °C. An interesting effect was identified in relaxation tests with loading at different strain rates. A kind of rebound effect was observed at the highest utilized strain rate of 10−2 s−1, which disappears with decreasing strain rate. Elastic strain proportions can be converted into plastic strain proportions during the application of the slow strain rate.

Influences of Surface, Heat Treatment, and Print Orientation on the Anisotropy of the Mechanical Properties and the Impact Strength of Ti 6Al 4V Processed by Laser Powder Bed Fusion

The scope of this work is to provide an overview of the influences of process parameters, print orientation, and post-process treatments of Ti6AlV4 processed by laser powder bed fusion on its microstructure and physical and mechanical properties and their anisotropic behavior. To avoid the influence of changes in powder quality and ensure comparability, experiments were carried out using a single batch of virgin powder. First, characterization of the density and surface roughness was performed to optimize the process parameters utilizing design of experiment. Tensile, notched bar impact and compression test specimens were built in three different orientations: vertically, horizontally, and inclined at 45° to the build plate. Later, the influence of the staircase effect and the possible course of anisotropy from vertical to horizontal were investigated. Subsequently, heat treatments for stress relief, furnace annealing, and hot isostatic pressing were performed. In addition to as-built samples, mechanical machining and a two-step electrochemical polishing surface treatment were applied to investigate the influence of the surface roughness. With parameter optimization, a relative density of 99.8% was achieved, and surface roughness was improved over default parameters, reducing Ra by up to 7 µm. Electrochemical polishing is a viable way to decrease the surface roughness. An Ra value of 1 µm and an Rz value of 4 µm can be achieved for 45° downskin surfaces with as-built surface roughness values of Ra 24 µm and Rz 117 µm. As-built and stress-relieved conditions show little anisotropy in their yield and tensile strength (max 2.7%), but there is a strong influence of the build orientation on necking, and brittle fracture behavior is shown due to the martensitic microstructure (up to 70%). Heat treatment can increase the ductility and further decrease the strength anisotropy with both furnace annealing and hot isostatic pressing delivering similar results for tensile properties, while angled samples exhibit behavior that is closer to vertical than horizontal, indicating a non-linear change in break behavior. Electrochemical polishing increases fracture necking, and its isotropy drastically increases from 4% to over 30% compared with as-built parts, which is close to the level of the machined specimen.

Quantitative Microstructural Characterization of Precipitates and Oxide Inclusions in Inconel 625 Superalloy Additively Manufactured by L-PBF Method

In this study, we perform quantitative characterization of precipitates and oxide inclusions in Inconel 625 additively manufactured by the laser powder-bed fusion (L-PBF) process. The application of different microscopy techniques allowed us to characterize the microstructure at micro- and nano-scale in the as-built and stress-relieved condition and correlate the features of grains and cellular substructure with parameters of particles along the planes parallel and perpendicular to the build direction. The optimized imaging conditions and image analysis procedure allowed easily distinguishing precipitates and oxide inclusions and performing their quantitative analysis. The results showed that intercellular areas are the preferential sites of precipitation of the Laves phase and NbC carbides with diameters in the range of 10 to 440 nm. Moreover, aluminum oxide inclusions with diameters in the range of 30 to 300 nm are randomly distributed. Regardless of the processing conditions of the examined samples, the influence of the stress-relief annealing on the secondary phases was not observed. In both the as-built and stress-relieved samples, the size of precipitates is in submicrometer scale. The analysis provided detailed information about the parameters of particles depending on the orientation versus the build direction. It was demonstrated that despite the tendency for columnar grain morphology and the anisotropy of the cellular substructure, the particle distribution is almost uniform throughout the volume of the additively manufactured L-PBF Inconel 625.Graphical

Low Cycle Fatigue Performance of Additively Processed and Heat-Treated Ti-6Al-7Nb Alloy for Biomedical Applications

In biomedical engineering, laser powder bed fusion is an advanced manufacturing technology, which enables, for example, the production of patient-customized implants with complex geometries. Ti-6Al-7Nb shows promising improvements, especially regarding biocompatibility, compared with other titanium alloys. The biocompatible features are investigated employing cytocompatibility and antibacterial examinations on Al2O3-blasted and untreated surfaces. The mechanical properties of additively manufactured Ti-6Al-7Nb are evaluated in as-built and heat-treated conditions. Recrystallization annealing (925 °C for 4 h), β annealing (1050 °C for 2 h), as well as stress relieving (600 °C for 4 h) are applied. For microstructural investigation, scanning and transmission electron microscopy are performed. The different microstructures and the mechanical properties are compared. Mechanical behavior is determined based on quasi-static tensile tests and strain-controlled low cycle fatigue tests with total strain amplitudes εA of 0.35%, 0.5%, and 0.8%. The as-built and stress-relieved conditions meet the mechanical demands for the tensile properties of the international standard ISO 5832-11. Based on the Coffin–Manson–Basquin relation, fatigue strength and ductility coefficients, as well as exponents, are determined to examine fatigue life for the different conditions. The stress-relieved condition exhibits, overall, the best properties regarding monotonic tensile and cyclic fatigue behavior.

Laser powder bed fused Inconel 718 in stress-relieved and solution heat-treated conditions

Inconel 718 superalloy cylindrical rods were fabricated using the laser powder bed fusion (L-PBF) technology in the vertical orientation. The rods were stress-relieved at 980 °C for 15 min before cutting them from the build plate. The microstructure in this condition exhibited a significant amount of undesirable needle-like δ-phase precipitates and a small amount of interdendritic Laves phase that is finer in size. Differential Scanning Calorimetry (DSC) was used to determine the temperatures for solid-state phase transformations and appropriate temperature for solution-treatment. Solution-treatment was performed at 1065 °C for 1 h, followed by air cooling. The microstructures were characterized with specific reference to δ-phase and Nb segregation. Solution-treatment at 1065 °C was found to result in a significant elimination of micro-segregation (mainly Nb), complete dissolution of δ phase, considerable Laves dissolution, and partly undissolved carbide particles (few nm in size). Solution-treatment did not produce a significant change in the grain morphology (columnar dendritic) on a plane parallel to the build direction but more recrystallized and equiaxed grains were formed on a plane perpendicular to the build direction. The hardness of the solution-treated sample is comparable with wrought 718 alloys but lesser (115 HV) than in the stress-relieved condition attributing to the annihilation of dislocation tangles.

Effect of T6 treatment on additively-manufactured AlSi10Mg sliding against ceramic and steel

In this study, the tribological properties of an AlSi10Mg alloy that was fabricated using laser powder bed fusion, an additive manufacturing technique, was investigated in both the as-built (but stress-relieved) and T6-treated condition. The stress-relieved condition consists of elongated Al grains and a dendritically-arranged nano-crystalline Si-phase. T6 treatment, a conventional heat treatment for cast AlSi10Mg alloys, caused this Si phase to dissolve, re-precipitate and coarsen, which resulted in a loss of hardness, toughness and strength. Dry sliding wear tests were conducted against both a bearing stainless steel and a much harder SiC, and with the sliding direction either perpendicular or parallel to the building direction. In almost all conditions it was found that the T6 treatment either had no statistically significant effect on the wear rate or was detrimental.

Investigation of the Microstructure and Compressibility of Biodegradable Fe-Mn-Cu/W/Co Nanostructured Alloy Powders Synthesized by Mechanical Alloying.

In this research work, the nanostructured Fe-Mn (BM0), Fe-Mn-Cu (BM1), Fe-Mn-W (BM2), and Fe-Mn-Co (BM3) biodegradable alloys were successfully synthesized using mechanical alloying. The microstructure of the synthesized alloys was examined using XRD, SEM equipped with EDS, and HRTEM techniques. The results obtained based on these techniques confirmed the development of nanostructured BM0, BM1, BM2, and BM3 alloys and homogenous solid solutions with an even elemental dispersion. The compressibility of the synthesized alloys was investigated experimentally and empirically in the as-milled conditions and after applying a stress relief treatment (150 °C for 1 h). The load applied for compaction experiments ranged from 25–1100 MPa with a rate of 1 mm/min. According to the experimentation performed in the current study, the relative density of the as-milled BM0, BM1, BM2, and BM3 alloys was 72.90% and 71.64%, 72.32%, and 72.03%, respectively. After applying the stress relief treatment, the density was observed to increase to 75.23%, 77.10%, 72.65%, and 72.86% for BM0-S, BM1-S, BM2-S and BM3-S samples, respectively. A number of compaction models were tested to identify the optimum models for predicting the compressibility behavior of nanostructured Fe-Mn, Fe-Mn-Cu, Fe-Mn-W, and Fe-Mn-Co alloys in the as-milled and stress-relieved conditions.

ATI 3-2.5

Abstract ATI 3-2.5 is a Titanium-3Aluminum-2.5Vanadium alloy that has higher strength than unalloyed titanium and is much more amenable to cold working than Ti-6Al-4V. This near-alpha, alpha-beta alloy is generally used in the annealed or cold-worked and stress-relieved conditions. This datasheet provides information on composition, physical properties, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: Ti-166. Producer or source: ATI.