Vickers Hardness Measurements Research Articles

Additive manufacturing of duplex stainless steel by DED-LB/M and PBF-LB/M – process-material-property relationships

Purpose Additive manufacturing (AM) of duplex stainless steels (DSS) is still challenging in terms of simultaneously generating structures with high build quality and adequate functional properties. This study aims to investigate comprehensive process-material-property relationships resulting from both laser-directed energy deposition (DED-LB/M) and laser powder bed fusion (PBF-LB/M) of DSS 1.4462 in as-built (AB) and subsequent heat-treated (HT) states. Design/methodology/approach Cuboid specimens made of DSS 1.4462 were generated using both AM processes. Porosity and microstructure analyses, magnetic-inductive ferrite and Vickers hardness measurements, tensile and Charpy impacts tests, fracture analysis, critical pitting corrosion temperature measurements and Huey tests were performed on specimens in the AB and HT states. Findings Correlations between the microstructural aspects and the resulting functional properties (mechanical properties and corrosion resistance) were demonstrated and compared. The mechanical properties of DED-LB/M specimens in both material conditions fulfilled the alloy specifications of 1.4462. Owing to the low ductility and toughness of PBF-LB/M specimens in the AB state, a post-process heat treatment was required to exceed the minimum alloy specification limits. Furthermore, the homogenization heat treatment significantly improved the corrosion resistance of DED- and PBF-processed 1.4462. Originality/value This study fulfills the need to investigate the complex relationships between process characteristics and the resulting material properties of additively manufactured DSS.

Effect of Pre-Deformation on Precipitation in Al–Zn–Mg–Cu Alloy

AbstractIn this work, strengthening effects and evolution of precipitates in a pre-deformed Al–Zn–Mg–Cu alloy during ageing were investigated using Vickers hardness measurements, tensile tests, and high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). It was found that all cold rolled conditions had higher mechanical strength than the non-deformed condition for all ageing times and that this effect increases at higher deformation ratios. It was also found that the non-deformed condition has a higher age hardening response than that of the cold rolled conditions. A homogeneous precipitate distribution was observed in the non-deformed condition, while the cold rolled conditions contained non-uniformly distributed precipitates due to the introduced dislocations. This led to larger precipitate sizes and a reduction in the precipitate number densities in the pre-deformed conditions. HAADF-STEM analysis revealed differences in the fraction of different precipitate types between the non-deformed and the cold rolled conditions. η', η2, and disordered η phase were observed in the non-deformed condition, while η', η2 and the newly identified Y phase were observed in the cold rolled conditions. The disordered η phase contained structural units of the η1 phase and was associated with reducing the lattice misfit between this phase and the Al matrix. Formation of the Y phase was related to an accelerated nucleation rate in the regions of high dislocation density. Graphical abstract

Investigation and Optimization of The Effect of Anhydrous Borax Mineral on The Vickers Hardness and Indentation Modulus Values of Iron Material

In this study, 5% and 10% by weight of anhydrous borax (AHB) was added to the iron (Fe) matrix material by powder metallurgy method and the effects of the additive ratio on the Vickers hardness (HV), Brinell hardness (HB) and Indentation modulus (EIT) values of the composites (Fe/AHB) were investigated. In the productions carried out using Taguchi experimental design method, AHB additive ratio, and sintering temperature parameters were selected as control parameters that were thought to affect the physical and/or mechanical properties of the Fe/AHB composite materials. The productions were carried out according to the Taguchi L4 orthogonal array, which was created depending on the control parameters and levels. Vickers hardness and indentation modulus measurements of pure iron and Fe/AHB composite materials were performed in accordance with BS EN ISO 14577-1 standard and Brinell hardness measurement was performed in accordance with TS EN ISO 6506-1 standard. According to the signal-to-noise ratio (S/N) analysis performed with the experimental data, it was determined that the 10% AHB additive ratio and 950oC sintering temperature optimized all the investigated properties of the Fe/AHB composite material. It was determined that the values for Vickers hardness, Brinell hardness and indentation modulus increased by 142.03%, 69.32% and 144.11%, respectively, in the levels where the properties of the composite material were optimized compared to pure Fe material. As a result of the qualitative examination of all samples after storage in a comfortable environment without daylight, it was also observed that the anhydrous borax additive delayed the corrosion time of pure iron material.

Effect of V and Mn addition on the HAZ softening and tensile properties of friction stir welded martensitic steel

This study explores the suppression of heat-affected zone (HAZ) softening in friction stir welding (FSW) joints formed above the A3 temperature of martensitic steels by leveraging short-time secondary hardening induced by vanadium (V) addition. The HAZ microstructure was examined using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and atom probe tomography (APT). Mechanical properties were evaluated through Vickers hardness (HV) measurements and tensile tests. Analysis of hardness distribution indicates effective HAZ softening suppression with V addition, attributed to the precipitation of fine and high-density V carbides within the HAZ. The inhibition of HAZ softening was correlated not only with V content but also with the A1 temperature of the steels, regulated by the manganese (Mn) content. However, at 1 mass% V content, intergranular brittle fracture occurred within the HAZ due to continuously distributed fine carbides and Mn segregation along the prior austenite boundary.

Evolution of fundamental mechanical properties with aliovalent Co/Cu partial substitution and preparation method for Y-123 system

This study investigates the effect of aliovalent Co/Cu replacement and preparation method on fundamental mechanical performance features of YBa2Cu3−xCoxO7−δ (Y-123) ceramic system depending on the crack propagation mechanism by Vickers hardness measurements (Hv) and mechanical investigation models for the first time. All the findings are verified by the scanning electron microscopy (SEM) examinations. Besides, the electron-dispersive X-ray (EDX) technique verifies the successful substitution mechanism. Besides, the Vickers hardness parameters improve systematically with the increment in the Co/Cu partial substitution (serving as a barrier) level due to formation of operable slip systems, ionic bond formations, and decrement of stress-amplified strain fields. Moreover, the Y-123 ceramic produced by solid-state reaction method and molecular weight of 0.20% presents the densest and smoothest surface morphology with the largest particle distributions and well-linked cobblestone-like grains. On the other hand, the Y-123 ceramic compounds produced by the sol–gel method are more sensitive and responsive to the indentation test loads. All the findings are wholly supported by the mechanical performance properties, including the shear modulus, resilience, and degree of granularity. Furthermore, the mechanical models indicate that every compound prepared exhibits the untypical reverse indentation size effect (RISE). Additionally, the modeling studies display that the induced cracking (IIC) approach is found to be the most appropriate method to examine true Vickers hardness parameters in the plateau limit regions. All in all, this comprehensive study reports efficiently exploiting the process–structure–property relationships in Y-123 ceramic material design for physical science and mechanical application fields using the aliovalent partial substitution and preparation condition.

Microstructural Investigations of Weld Deposits from Manganese Austenitic Alloy on X2CrNiMoN22-5-3 Duplex Stainless Steel

Duplex stainless steels are materials with high performance under mechanical stress and stress corrosion in chloride ion environments. Despite being used in many new applications such as components for offshore drilling platforms as well as in the chemical and petrochemical industry, the automotive industry, etc., they face issues of wear and hardness that limit current applications and prevent the creation of new use opportunities. To address these shortcomings, it is proposed to develop a hardfacing process by a special welding technique using a universal TIG source adapted for manual welding with a pulsed current, and a manganese austenitic alloy electrode as filler material. The opportunity to deposit layers of manganese austenitic steel through welding creates advantages related to the possibility of achieving high mechanical characteristics of this steel exclusively in the working area of the part, while the substrate material will not undergo significant changes in chemical composition. As a result of the high strain hardening rate, assisted mainly by mechanical twinning, manganese austenitic alloys having a face-centered cubic crystal lattice (f.c.c) and low stacking fault energy (SFE = 20–40 mJ/m2) at room temperature, exhibit high wear resistance and exceptional toughness. Following cold deformation, the hardness of the deposited metal increases to 465 HV5–490 HV5. The microstructural characteristics were investigated through optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), X-ray diffraction (XRD), and Vickers hardness measurements (HV). The obtained results highlighted the feasibility of forming hard coatings on duplex stainless steel substrates.

Cu–Mg dilute alloys- Assessment of strengthening, internal friction, and electrical conductivity

Overcoming the strength-conductivity trade-off has long been an issue for commercial copper alloys. However, a synergy between strength and electrical conductivity can be achieved by reasonable adjustment of the microstructure. It is known that the formation of Short-Range Order (SRO) in a solid solution can change the mechanical and electrical behavior of the materials. Currently, the prediction of SRO formation is widely based on computational techniques. In the present study, Miedema's thermodynamical approach is applied for the assessment of alloying elements' potential to form SRO in the copper lattice. According to this methodology, magnesium tends to form SRO with copper. The mechanical, electrical, and structural properties of the oxygen-free copper (Cu-OFC), Cu–Mg0.14 wt%, and Cu–Mg0.50 wt% strips fabricated by continuous extrusion forming process (Conform) have been investigated. According to the optical microscopy investigations, the average grain sizes of the Mg alloyed samples were observed to be lower compared to that of OFC. The Vickers hardness measurements were carried out and the hardness values for Cu-OFC, Cu–Mg0.14, and Cu–Mg0.50 samples were recorded as 56.3 HV, 76.05 HV, and 87.68 HV, and the yield strengths as 80, 150 and 260 MPa, respectively. A decrement in electrical conductivity was observed with the increasing Mg addition. Dynamic elastic modulus test measurements, which refer to internal friction, have been performed by impulse excitation technique to elucidate the presence of SRO in the dilute Cu–Mg systems. The anomalous “bump” formation in the temperature-elastic modulus profiles of the Cu–Mg samples was remarkable which has been attributed to the SRO formation.

Tailoring the structural, morphological, surface wettability and hardness features of Makrofol HS for surface applications: effect of DBD treatment

ABSTRACT In current research, Makrofol HS polymeric films have been utilized to evaluate the alterations in the surface properties under an atmospheric-pressure dielectric barrier discharge (DBD) plasma source. Upon DBD plasma exposure with various exposure durations ranging from 10 min to 120 min, the structural, surface wettability, surface free energy, surface roughness, and hardness features of Makrofol HS films have been studied and analyzed using different techniques. The FTIR spectra demonstrated that small changes in the band intensities correspond to the C-O-C as well as C=O bonds. Further, the changes in the absorption bands are correlated to the treatment time, leading to two critical processes, degradation, and crosslinking. The results of surface wettability displayed that the liquids' contact angle decreased from 84 ± 3o, 77 ± 3o and 62 ± 2o for water, glycerol, and dimethyl to 45 ± 1o, 42 ± 1o, and 36 ± 1o for untreated and treated samples at the highest treatment time, respectively. Also, the surface free energy significantly amended with increasing plasma exposure time. This modification in the treated surface indicates the increase in the polar groups on the treated surfaces, which then become hydrophilic surfaces. The samples' surface roughness parameters Ra, Rq, and Rz increased from 0.057 ± 0.003, 0.084 ± 0.004 and 0.366 ± 0.02 mm for untreated samples to 1.463 ± 0.073, 1.707 ± 0.085, and 6.839 ± 0.34 mm for treated samples at the highest treatment time, respectively. The Vickers hardness measurements showed an increase in the Vickers hardness from 12.31 ± 0.61 kgf/mm2 for the untreated sample to 44.89 ± 2.24 kgf/mm2 for the treated sample at the highest duration.

Mechanical Properties of Nano-Crystalline Glass-Carbomer Cements Used in Dentistry.

The main aim of this study was to assess the impact of the environment on the mechanical and tribological properties of glass-carbomer cements used in dentistry. The properties of the Glass Cements Polyalkene (GCP) Glass Fill material, belonging to glass-polyalkene cements, were tested after placing it in various environments: air, distilled water, artificial saliva simulating a neutral environment (pH = 7), and simulating inflammation (pH = 4). The research material included four samples and a two-year reference material. The analysis of volumetric consumption and the assessment of the impact of solubility on the stability of glass-carbomer cements were carried out using tribological measurements and Vickers hardness measurements. In addition, microstructural characterization of the materials was performed using scanning electron microscopy (SEM). It was observed that the lowest wear (0.04%), the most stable microstructure, and the lowest average hardness (21.52 HV 0.1) were exhibited by the material stored in artificial saliva simulating a neutral environment (pH = 7). The least stable microstructure and statistically the highest hardness (77.3 HV 0.1) was observed in the test sample, which was stored in air for two years and then in distilled water. The highest consumption (0.11%) was recorded in the case of cement placed in artificial saliva simulating inflammation (pH = 4). The results obtained in this study indicate specific trends in the influence of the environment in which the tested cement is located, such as air, distilled water, air/distilled water, artificial saliva simulating a neutral environment, and simulating inflammation, on its structure, hardness, and wear.

Impact of CAD/CAM Material Thickness and Translucency on the Polymerization of Dual-Cure Resin Cement in Endocrowns.

The objective of this study is to evaluate the impact of the thickness and translucency of various computer-aided design/computer-aided manufacturing (CAD/CAM) materials on the polymerization of dual-cure resin cement in endocrown restorations. Three commercially available CAD/CAM materials-lithium disilicate glass (e.max CAD), resin composite (CERASMART), and a polymer-infiltrated ceramic network (ENAMIC)-were cut into plates with five different thicknesses (1.5, 3.5, 5.5, 7.5, and 9.5 mm) in both high-translucency (HT) and low-translucency (LT) grades. Panavia V5, a commercial dual-cure resin cement, was polymerized through each plate by light irradiation. Post-polymerization treatment was performed by aging at 37 °C for 24 h under light-shielding conditions. The degree of conversion and Vickers hardness measurements were used to characterize the polymerization of the cement. The findings revealed a significant decrease in both the degree of conversion and Vickers hardness with increasing thickness across all CAD/CAM materials. Notably, while the differences in the degree of conversion and Vickers hardness between the HT and LT grades of each material were significant immediately after photoirradiation, these differences became smaller after post-polymerization treatment. Significant differences were observed between samples with a 1.5 mm thickness (conventional crowns) and those with a 5.5 mm or greater thickness (endocrowns), even after post-polymerization treatment. These results suggest that dual-cure resin cement in endocrown restorations undergoes insufficient polymerization.

Effect of Molybdenum on the Mechanical and Corrosion Properties of Ti-xMo-2Fe Beta Alloys

Titanium alloys are currently used in offshore industries. The titanium alloys used in offshore plants need to have excellent corrosion resistance and mechanical properties because offshore plants are exposed to harsh corrosive environments. At this time, the Ti-6Al-4V ELI alloy is mainly used in offshore plants because it has excellent mechanical properties and corrosion resistance. However, Ti-6Al-4V ELI alloy has the disadvantage of poor formability. To improve this, studies on metastable beta-Titanium alloys with a BCC structure are being actively conducted. In this study, a metastable beta-titanium alloy was fabricated using Mo, which is inexpensive and improves corrosion resistance, and Fe, which improves strength, among the titanium beta stabilizer elements. After the Ti-6Al-4V ELI and Ti-xMo-2Fe alloys solution treatments, electrochemical corrosion experiments were conducted to analyze corrosion characteristics, and mechanical properties were also analyzed through compression tests at room temperature and Vickers hardness measurement. Corrosion properties and the mechanical properties of Ti-xMo-2Fe alloy were considered in connect experiments such as microstructure analysis and hardness measurement. It was confirmed that the corrosion resistance of the Ti-xMo-2Fe alloy was better than that of the Ti-6Al-4V ELI alloy, and it was confirmed that the compressive strength and elongation rate of Ti-xMo-2Fe with its BCC structure get higher than Ti-6Al-4V ELI alloy.

A brief study of electrical and biological properties of BNT6BT/ZnO-HA Composite

The discovery of the piezoelectric properties of natural bone and their influence on bone growth within scaffolds has spurred researchers to investigate a range of bio-piezoelectric composite materials. By exploring these materials, researchers aim to better understand how piezoelectricity can be harnessed to promote bone growth and tissue regeneration, potentially leading to new breakthroughs in the field of regenerative medicine. In this study, the piezoelectric material, Bi0.5Na0.5TiO3-0.6BaTiO3/nano ZnO (BNT6BT/ZnO) and the biological hydroxyapatite (HA) were separately synthesized using the sol-gel method. The composite samples consisting of BNT6BT/ZnO and HA were fabricated using isostatic cold pressing. The composition and phase structure were studied using the X-ray diffraction (XRD) analysis, and the scanning electron microscopy (SEM) was used to study the microstructure and morphology. The presence of different phases and the distribution of elements were examined using EDAX elemental analysis and its corresponding maps. Among the composite samples the one containing 10 wt% HA (BNT6BT/ZnO-10HA) possessed the best dielectric properties. The Vickers hardness measurements showed that the addition of HA to the piezoelectric phase BNT6BT/ZnO results in higher hardness values, which expects to increase the fracture toughness of HA due to the higher elastic modulus to hardness ratio (E/H) of composite samples compared to pure HA. The in vitro bioactivity of the samples was tested in simulated body fluid (SBF) solution and the cell culture analysis was performed to examine the biocompatibility of the samples. Accordingly, apatite was deposited on the surface of the samples and all of the composite samples were bioactive. Furthermore, the BNT6BT/ZnO-10HA sample containing the largest amount of deposit showed the highest optical density (OD) in the MTT test.

Lightweight Segmentation Neural Networks for Measuring Vickers Hardness

Lightweight Segmentation Neural Networks for Measuring Vickers Hardness

Effect of Carburization on the Microstructure and Laser Weldability of 316L Stainless Steel

This study aims to investigate the influence of the carburizing layer on the microstructure of laser-welded joints in 316L stainless steel, aiming to enhance the properties of stainless steel components through the incorporation of carburization. Through a comprehensive experimental approach, including nanoindentation and Vickers hardness measurements, the microstructural analysis of the laser-welded specimens was conducted. The nanoindentation results reveal a significant increase in hardness, with the carburizing layer exhibiting a remarkable 215% improvement compared to the base material. In order to effectively harness the wear resistance for various applications, the examination of macroscopic characteristics in laser-welded joints reveals the necessity of regulating heat input and minimizing defects to attain welds of superior quality. Additionally, the phase transformation behavior of stainless steel during welding was found to be altered due to dilution in the fusion zone and the presence of high carbon content in the heat-affected zone of the carburizing layer. Overall, this research provides valuable insights into the microstructural changes induced by carburization and its implications for the welding performance and mechanical properties of stainless steel.

Gamma prime formation in nickel-based superalloy IN738LC manufactured by laser powder bed fusion

Complex components for high-temperature gas turbine applications require materials that offer a combination of excellent high-temperature strength and oxidation resistance. Nickel-based superalloys with high gamma prime (γ´) volume fractions are particularly suited for these applications, especially combined with additive manufacturing for intricate geometries. Despite the complex thermal history that these materials experience during laser powder bed fusion (LPBF) processing, γ´formation is suppressed when manufacturing IN738LC, which has a medium equilibrium γ´content of about 40–50 vol%. This study follows γ´formation in LPBF IN738LC during subsequent annealing treatments at temperatures ranging from 745 °C to 865 °C, creating an experimentally determined TTT (temperature-time-transformation) diagram. This diagram is largely based on scanning electron microscopy (SEM) imaging supported by Vickers hardness measurements and scanning transmission electron microscopy (STEM) bright field imaging. Atom probe tomography (APT) of the as-built material indicated nm-sized regions depleted in Cr and enriched in Ni, Al, and Ti, but show no characteristic superlattice patterns in TEM diffraction. APT and TEM diffraction analysis of material annealed at 850 °C for 3 min confirmed the presence of the γ´phase but indicated that γ´had formed through spinodal decomposition instead of precipitation.

Kinetics of Intermetallic Phase Precipitation in Manual Metal Arc Welded Duplex Stainless Steels.

The article presents the influence of heat treatment on the kinetics of transformations in lean duplex LDX2101 steel and a weld made of standard duplex 2209 material, which was welded by manual metal arc welding. Changes in the microstructure, hardness, and magnetic phase content were analyzed after heat treatment was conducted at a temperature of 800 °C for a period ranging from 15 to 1440 min. Light and scanning microscopy, Vickers hardness measurements, and magnetic phase content measurements using a ferritoscope were used for the research. In the LDX2101 steel, the presence of δ-ferrite and γ austenite was identified and additional Cr2N nitrides were observed in the heat-affected zone. After heat treatment, the decomposition of δ ferrite into γ2 austenite and Cr2N nitrides was observed in both areas. In the case of weld made by the coated electrode in 2209 grade, a ferritic-austenitic microstructure with allotriomorphic austenite (γA), Widmanstätten austenite (γW), and idiomorphic austenite (γI) and δ-ferrite area with "bee swarms" of fine precipitations of chromium nitrides Cr2N and non-metallic inclusions (NMIs) of slag, formed during the welding process, are observed in the as-welded state. After heat treatment, the presence of the χ phase (after 15 min of annealing) and the σ phase (after 120 min of annealing) was additionally identified. The kinetics of intermetallic phase evolution in welds made from 2209 material were presented. The obtained results of hardness measurements and metallographic tests were correlated, which allowed for a quick check of the precipitation processes on the used element.

The mosaic tesserae in the industrial Byzantine wine press, Yavne, Israel: A natural unusually hard chalk or a chemically transformed chalk?

Many of the surfaces of a large industrial scale wine press from the Byzantine period in Yavne, Israel, are covered in mosaic tesserae. These surfaces are part of the grape presses, storage pools, fermentation pools and also the walkways between these structures. The calcitic tesserae resemble limestone in color, texture and fracture properties. We were therefore surprised to discover that they are more disordered at the atomic level than consolidated limestone and in fact they are as disordered as porous and friable chalk. In addition SEM examination of fracture surfaces reveals abundant nannofossils, mostly coccoliths and foraminifera; properties that are also reminiscent of chalk. The nanofossil identifications shows that the tesserae are from the Middle Eocene, and this includes the chalky Maresha Formation that outcrops about 15kms from the site. SEM examination of polished surfaces shows that the larger pores of tesserae are lined with euhedral calcite crystals. Vickers hardness measurements show that the tesserae are much harder than chalk, and are comparable to limestone. There are two scenarios for explaining these seemingly contradictory observations. One scenario is that a chalky limestone geological formation with all these properties exists somewhere in the Mediterranean region and is the source of the raw material for the tesserae. The second scenario is that the Byzantine constructors of the wine press transformed a chalk into a harder and more consolidated material. Chalk transformation processes akin to plaster formation can be excluded based on the analyses of the stable carbon isotopic compositions of the tesserae, as well as their 14C concentrations. A chemical transformation using a weak acid that would only affect the calcite in the vicinity of the accessible pores, and leave the bulk of the chalk and its microfossils in a good state of preservation, is conceivable. In fact a by-product of producing wine is vinegar and the acetic acid of the vinegar could conceivably have been used for this purpose. If indeed a chemical transformation of soft chalk into a hard durable material was used, this would represent a “lost” technology that might even be useful in present times.

Influence of Mo Content on the Precipitation Behavior of 13Ni Maraging Ultra-High Strength Steels

This study offers valuable insights into the precipitation behavior of 13Ni maraging steels, emphasizing the role of molybdenum content in their microstructure, strengthening, and precipitate evolution. Precipitate morphology and crystallography were examined using a combination of high-resolution transmission electron microscopy and selected area electron diffraction. Strengthening mechanisms were assessed through Vickers hardness measurements. All the examined samples exhibited a lath martensite microstructure and displayed an increasing hardness over the aging time. The molybdenum content not only influenced the presence of retained austenite in the initial microstructure but also affected the type of precipitates formed during the early aging stages. Initially, Ni3Mo precipitates were formed, succeeded by the formation of more stable Fe2(Mo,Ti) Laves precipitates. The ultra-high strength of 13Ni maraging steels arises from the combination of the precipitate type and size distribution. The base composition of 13Ni maraging steels achieved a peak hardness of 798 HV1 through the precipitation of Laves Fe2(Mo,Ti) phases ranging from 3 to 14 nm in diameter.

PRODUCTION AND CHARACTERIZATION OF 2024 ALUMINUM ALLOYS

This study aims to give theoretical information about the production and characterization of mechanical properties of 2024 aluminum alloys. AA2024 alloy; It consists of components such as aluminum, copper, magnesium and manganese, and the production of the alloy is usually carried out by different methods such as casting, rolling, extrusion and powder metallurgy. The choice between production methods should be made by considering the purpose and properties of the alloy. While the casting method is used for the production of large-sized parts, the rolling method is suitable for the production of thin sheets and strips, and the extrusion method is suitable for the production of profiles and pipes of various shapes. The powder metallurgy method, on the other hand, is carried out by shaping the powdered components of the alloy with a special pressing process and then sintering at high temperature. Alloys produced by this method exhibit high strength properties with their high density and homogeneous microstructures. The mechanical properties of AA2024 alloy are generally determined using various characterization methods such as tensile test, hardness measurement and fatigue life tests. The tensile test is used to determine the tensile strength, tensile elongation ratio and elastic tension properties of the alloy. The hardness measurement is used to determine the surface hardness of the alloy. Surface hardness can be performed using Brinell, Vickers and Rockwell hardness measurement methods. The fatigue life test is used to determine the fatigue strength of the alloy. In this test, the fatigue life of the specimen under repetitive loads is determined. The mechanical properties of AA2024 alloy may vary depending on production methods, alloy components, temperature and environmental conditions. Therefore, the mechanical properties of the alloy must be optimized for a particular application. 2024 aluminum alloys produced by powder metallurgy method are expected to exhibit high density, homogeneous microstructure and high strength properties as a result of hardness, tensile and fatigue tests.

Effect of Cr and Y on the microstructure and mechanical properties of Fe-Cr-Al alloys during corrosion-aging in superheated steam at 500 °C

The α-α’ phase separation of Fe-Cr-Al alloys during long-term service at 475–500 °C may lead to the increase of strength and hardness and the decrease of ductility, which will limit the application of Fe-Cr-Al alloys as accident tolerant fuel (ATF) cladding material. The mechanical behavior and microstructure evolution of Fe-12Cr-5Al, Fe-12Cr-5Al-0.01Y, Fe-20Cr-5Al and Fe-20Cr-5Al-0.02Y (wt%) alloys in 500 °C superheated steam for 2000 h have been investigated by tensile test, Vickers hardness measurement, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), three-dimensional atom probe (3DAP) and thermodynamic calculations. Results show that increasing the Cr content may refine the grain and improve tensile strength of the alloy, while adding trace Y has negligible effect on the grain size and tensile strength of the alloy; the corrosion-aging hardening of 20CrY and 20Cr alloys is attributed to the α-α’ phase separation, which is closely related to the high content of Cr in the alloy. The addition of trace Y promotes the nucleation and growth of α’ phase in alloys with the content of 20%Cr during the corrosion-aging process but has insignificant influence on the mechanical properties of the alloy.