Search

A homogenized, supersaturated AlZnMgZr alloy was processed via severe plastic deformation (SPD) using a high-pressure torsion (HPT) technique for different revolutions at room temperature to obtain an ultrafine-grained (UFG) microstructure. The microstructure and mechanical properties of the UFG samples were then studied using transmission electron microscopy (TEM), differential scanning calorimetry (DSC), and tensile and hardness measurements. The main purpose was to study the effect of shear strain on the evolution of the microstructure of the investigated alloy. We found a very interesting evolution of the decomposed microstructure in a wide range of shear strains imposed by HPT. While the global properties, such as the average grain size (~200 nm) and hardness (~2200 MPa) appeared unchanged, the local microstructure was continuously transformed. After 1 turn of HPT, the decomposed UFG structure contained relatively large precipitates inside grains. In the sample processed by five turns in HPT, the segregation of Zn atoms into grain boundaries (GBs) was also observed. After 10 turns, more Zn atoms were segregated into GBs and only smaller-sized precipitates were observed inside grains. The intensive solute segregations into GBs may significantly affect the ductility of the material, leading to its ultralow-temperature superplasticity. Our findings pave the way for achieving advanced microstructural and mechanical properties in nanostructured metals and alloys by engineering their precipitation and segregation by means of applying different HPT regimes. [ABSTRACT FROM AUTHOR]

The introduction of high-entropy alloys, notable for their increased hardness and thermal stability, gave impetus to the study of their properties in coatings. High-entropy metal coatings are characterized by high hardness, ranging from 7 to 19 GPa. The general laws governing the influence of various parameters on the mechanical properties of high-entropy metal coatings were analyzed. Single-layer metal, nitride, oxide, and carbide coatings and multilayer nitride coatings from high-entropy alloys produced by different deposition techniques were examined. The phase composition, structure, hardness, elastic modulus, and friction coefficient of the coatings were determined. The mechanical properties of high-entropy coatings, along with those of cast alloys, depend on the lattice parameter. With increase in the lattice parameter in bcc metal coatings, the elastic modulus and hardness decrease. The increased hardness of vacuum high-entropy coatings contributes to decrease in their friction coefficient compared to the cast state. The influence of pressure in the sputtering chamber and the voltage applied to the substrate on properties of the nitride coatings was established. The capabilities of producing thick (up to 80 μm) coatings combining metal and nitride interlayers from high-entropy alloys and determining their properties were shown. For the high-entropy carbide in the TiZrNbVTaHf system, the influence of the lattice parameter on hardness was revealed. The lowest friction coefficient (0.05) was observed in high-entropy oxide coatings. The high-entropy coatings showed high hardness. A hardness level of 19 GPa was reached for a metal coating based on the TiZrNbTaHfCr alloy, 63 GPa for a nitride coating based on the TiZrNbVHf alloy, and 48 GPa for a carbide coating based on the TiZrNbVHfTa alloy. The analysis showed that nitride coatings were the hardest, while the lowest friction coefficient was possessed by oxide coatings. [ABSTRACT FROM AUTHOR]

Additive manufacturing processes play a disruptive role in several industrial sectors. Among them, wire arc additive manufacturing (WAAM) is a very promising process for the production of large-scale steel components and structures. As a common characteristic of innovative technologies, this process requires additional research and experimental work in order to understand how its thermal cycles will modify the mechanical and metallurgical properties of the manufactured components. Considering the lack of literature on the properties of WAAM components from specific steel alloys, the present work proposes a benchmark evaluation of five different steel filler metals based on their mechanical properties and operational parameters when applied for additive manufacturing. The mechanical properties, such as the tensile strength, yield strength, elongation, Charpy impact toughness, and hardness, were evaluated together with operational parameters such as cost, printability, spatter, and fume formation during manufacturing, defect-free printing, and heat input. These were analyzed in order to obtain a full evaluation and comparison of the five filler metals. The experimentally determined results of every above-mentioned aspect were higher or similar to the values found in the literature for generic steel filler metals used in additive manufacturing. This means that a designer or welding engineer can select the WAAM steel filler metal for further testing based on the welding wire datasheet. Besides that, a comparison was performed between blocks manufactured by WAAM with some frequently used base metals, in plate format, confirming its applicability. [ABSTRACT FROM AUTHOR]

Under industrial conditions, melt for the production of cast products from wear-resistant steels is produced mainly by modifying iron-carbon-based alloys with ferrotungsten. Ferrotungsten production is a material-intensive and energy-consuming process that does not allow the direct use of ore concentrates as a modifier due to their complex chemical composition. The growth of the global consumption of wear-resistant steels and products from them necessitates search for and development of alternative methods to produce such alloys. The aluminothermic remelting of mixtures consisting of scale, reducing agent, and tungsten-containing component is aimed at solving the problems of processing man-made formations to produce metal products in the form of wear-resistant steel castings. Scheelite concentrate is used in the experimental process, which makes it possible to reduce the processing chain of tungsten use to one stage. The results of studies of the aluminothermal process of producing castings from thermite compositions are presented. The pattern of influence of the content of reducing agent and scheelite concentrate on the physical and mechanical properties of the metal is experimentally established. [ABSTRACT FROM AUTHOR]

Quenching is a swift way of returning metal back to ambient temperature in order to acquire a certain property. Although it is often used to enhance the hardness of metals and their microstructure, it equally causes a serious variation in the mechanical and physical properties of the metals. This research focuses on quenching media's effect on the microstructure and mechanical properties of a 150mm x 80mm x 8mm welded mild steel plate through microscopic examination, metallography mounting, surface grinding, and surface polishing. Microstructural analysis with hardness and impact test was carried out on the steel plate using water, air, and oil as the quenching media. The results of the test show the Vickers Pyramid Number (HV) for water, oil, and air to be 284.2, 270.9, and 262.2 HV for the base metal, heat affected zone (HAZ), and weld metal (WM), respectively. The amount of energy absorbed by the three specimens during fracture is 23.12, 25.27, and 26.83 J, respectively. The test further indicates that the water-quenched media exhibited mostly martensitic structures and held back austenite with many structures of cementite while the oil and air media exhibited martensite phase and refined grains structures individually. It is therefore concluded that air is more suitable to cool the weld metal for damping applications in engineering. [ABSTRACT FROM AUTHOR]

Objective: medium and low alloy steel have good mechanical properties and are widely used in the manufacture of key parts such as high-speed rail, automobiles, and aircrafts. Hardness is an important physical property of metal materials, which directly affects the mechanical properties of metal materials as key components. Therefore, the detection of hardness is of great significance. The traditional hardness testing method is to apply force to the sample to produce indentation and then determine the hardness of the sample by the depth of the indentation. Due to the existence of indentation in this method, the sample will be destroyed, so it can only be used for the random inspection of sample hardness parameters, which cannot meet the reality of the hardness testing of the key parts of the equipment in a running state. Therefore, it is necessary to explore a non-destructive testing method for the hardness of low and medium alloy steel based on LIBS testing technology. Method: based on laser-introduced breakdown spectroscopy (LIBS) technology and combined with chemometrics, this study took the medium-and-low alloy steel as the research object to monitor the quality of train wheels. Firstly, LIBS spectra of 12 standard steel samples with different hardness characteristics were acquired and compared. Secondly, the original spectrum was preprocessed using methods such as smoothing correction, multiplicative scatter correction, AsLS, and AirPLS to select the optimal preprocessing method. It was found that the model established by means of multiplicative scatter correction (MSC) combined with baseline estimation and de-noising using sparsity (BEADS) showed the best performance, in which the cross-validation of correlation coefficient (Rcv) was 0.9909 and the standard deviation of cross-validation (RMSECV) was 14.6935. To simplify the calculation and improve model accuracy, the uninformative variable elimination (UVE), competitive adaptive reweighted sampling (CARS), and successive projections algorithm (SPA) were used to select the effective spectral bands and create the partial least squares and partial minimum support vector machine (SVM) models, respectively. The results showed that the CARS-LS-SVM model obtained more accurate prediction results than the CARS-PLS model, whose Rp and RMSEP values were 0.9966 and 9.4800, respectively. Conclusion: it is concluded that the wavelength selection can not only eliminate the interference information, and simplify the modeling and calculation process of LIBS spectral data but also improve the accuracy of the detection model, thus making it feasible to rapidly detect steel hardness. The results show that it is feasible to predict the hardness of the medium-and-low alloy steel using LIBS combined with the LS-SVM model, which can be further used as a technical method to detect the quality of steel and the performance of the key components for the quality supervision of steel. [ABSTRACT FROM AUTHOR]

Ultra-high-strength steel significantly contributes to lightweight design. However, it is essential that excellent mechanical properties are maintained after the applied welding process in terms of structural integrity, strength and ductility. This study investigates the microstructural and mechanical properties of metal active gas-welded X-joints of 20-mm-thick S1100 thermomechanically rolled plates with undermatched alform 960 L-MC filler metal. Welding was carried out fully automated in order to obtain uniform properties of the welds for different heat inputs in flat (PA) and vertical up (PF) positions. The mechanical properties of weldments were characterized by hardness, impact and tensile tests and complemented by microstructural analysis using optical and scanning electron microscopy. Different heat inputs due to altered welding positions caused changes in prior austenite grain size and orientation in the weld metal (WM) microstructure which is presented and discussed in detail. The microstructures of the WM consist of ferrite, while the heat-affected zone (HAZ), which was exposed to several thermal cycles, is dominated by bainite and martensite-austenite (M/A) constituents. While in the HAZ the top layer shows fresh martensite of high hardness, the HAZ of filler and root passes was tempered showing lower hardness values. Transverse tensile tests always failed in the weld metal not fulfilling base materials strength requirements. Although the weld metal microstructure consisted of acicular ferrite in PA and PF position, PF weld has lower toughness. [ABSTRACT FROM AUTHOR]

Unevenness of wearing of working surfaces of parts, operating under friction, is a common cause for beginning of renovation and replacement times. One of the methods to avoid this problem is formation of surfaces of a variable composition and properties by arc surfacing. The work presents comparative analysis of the hardness and structure of the metal, deposited with pre-application of titanium and boron carbides on the processed surfaces. These materials were selected, proceeding from their impact on the deposited metal mechanical properties. The hardness, structure and composition of the deposited metal were studied. Hardness dependence on the heat input and material consumption in individual zones of the bead cross-section was analyzed. Regularities were established between accumulation in the formed beads of material pre-applied on the processed surface and the significance of structural transformations. A similar influence of both the carbides on the deposited metal structure was found. Bead metal hardness is 1.5 times higher at B4 C application, than in the case of using TiC. X-Ray spectral microanalysis revealed the influence of free carbon, formed as a result of compound decomposition, on the structural transformation in the deposited metal. It was found that the largest accumulations of bainite are characteristic for zones with the highest carbon content. It was determined that pre-application of carbides, using the most common surfacing materials, allows producing deposited metal, matching by its properties the metal deposited with PP-Np-152 wire. [ABSTRACT FROM AUTHOR]

Uneven wearing of working surfaces of parts, operating under friction, is a common cause for beginning of renovation and replacement times. One of the methods to avoid this problem is formation of surfaces of a variable composition and properties by arc surfacing. The work presents comparative analysis of the hardness and structure of the metal, deposited with pre-application of titanium and boron carbides on the processed surfaces. These materials were selected, proceeding from their impact on the deposited metal mechanical properties. The hardness, structure and composition of the deposited metal were studied. Hardness dependence on the heat input and material consumption in individual zones of the bead cross-section was analyzed. Regularities were established between accumulation in the formed beads of material pre-applied on the processed surface and the significance of structural transformations. A similar influence of both the carbides on the deposited metal structure was found. Bead metal hardness is 1.5 times higher at B4C application, than when TiC is used. X-Ray spectral microanalysis revealed the influence of free carbon, formed as a result of compound decomposition, on structural transformation in the deposited metal. It was found that the largest accumulations of bainite are characteristic for zones with the highest carbon content. It was determined that pre-application of carbides, using the most common surfacing materials, allows producing deposited metal, matching by its properties the metal deposited with PP-Np-152 wire. [ABSTRACT FROM AUTHOR]

Copyright of Steel Pipe is the property of Steel Pipe Magazine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aluminium and its alloys have an excellent mechanical property in that metal matrix composite has a promising role in the field of automobile and aviation. This work aims to investigate the hardness and impact strength of aluminium Al2024, Al6061 and Al7075 alloy reinforced with a weight fraction of fine greenish silicon carbide 7% and chopped E-glass fiber 3%. The metal matrix composite plates were welded by using the friction stir welding process at 550, 850 and 1150 rpm with a feed rate of 40, 80, 120 mm/min. Hardness specimens are prepared as per ASTM-E-92 and investigated the hardness of welded and unwelded (base metals and composite metal) in nugget zone, HAZ and TMAZ with the help of Vickers hardness test machine. Impact strength specimens are prepared as per ASTM-E-23. The results were compared with welded and unwelded aluminium specimens. [ABSTRACT FROM AUTHOR]

The present work examines the effects of pack‐boronizing treatment on the surface characteristics of modified industrial cold‐work tool steel intended for polymer crushing. Particular attention is paid to optimizing the process parameters to improve the tool surface properties and thus achieve a satisfactory tool life. To this end, a series of samples were subjected to boronizing treatment within the temperature range from 800 °C to 1000 °C for soaking periods of 2 h, 4 h, 6 h and 8 h. The structural and mechanical properties of the modified metal surface were analyzed using optical and scanning electron microscopy, x‐ray diffraction, microhardness testing and pin‐on‐disk tribotesting. The adhesion quality of the boride layer‐substrate was carried out using the adhesion test Daimler Benz Rockwell‐C. The corrosion properties were determined by the electrochemical polarization method. Experimental results showed that the optimum temperature‐temporal conditions of 900 °C/4 h that are the intermediate processing parameters led to a better compromise between the intended properties, in terms of resistance to wear and corrosion, as well as adhesion quality. [ABSTRACT FROM AUTHOR]

The structural and mechanical analyses were performed on an aluminum alloy (AlSi10Mg) fabricated using a laser powder bed fusion process where the laser power and the scan speed were varied. An x-ray diffraction analysis was performed on the specimens and Mg2Si clusters were detected. A heat-affected zone and fine and coarse grain regions were observed using optical microscopy and a field emission scanning electron microscope. By increasing the laser power at a fixed scan speed, the microstructure becomes finer, which was further confirmed by measuring the size of grains. By increasing the scan speed at a fixed laser power, the microstructure was found to be coarser. Relative density, microhardness, and surface roughness tests were performed on specimens to study the mechanical properties. An increase in laser power improved the relative density and microhardness wherein the surface roughness reduced. An increase in scan speed resulted in a decrease in relative density and microhardness of the samples, which increased the surface roughness. [ABSTRACT FROM AUTHOR]

This paper deals with the experimental investigation of effect of reinforcement Fly ash and Zirconium on mechanical properties and tribological properties of aluminium metal matrix composites samples, processed by stir casting method. Three sets of composites were prepared with fixed percentage of 1% of fly ash and 5% Zirconium by weight fraction. The evaluated properties of the samples were tensile strength, hardness and microstructure, in the presence of Zirconium 5% and fly ash 1% with aluminium 6061, aluminium 7075, and aluminium 8011. It was observed that the hardness was increased and correspondingly, the increase in tensile strength was also observed, and wear rate decreases with the hybrid metal matrix composites in comparison with base metal. Aluminium alloy constitutes a very important engineering material, and is widely employed in the aircraft and aerospace industry for the manufacturing of different parts and components. It is due to its high strength to density ratio that it is a sought after metal matrix composite. [ABSTRACT FROM AUTHOR]

Glass laminate aluminum reinforced epoxy (GLARE) mixes a layer of aluminum with fiber-reinforced epoxy to constitute a hybrid composite. During this investigation, plain E-glass fiber/epoxy specimen in addition to hybrid composite laminated epoxy specimens reinforced with both E-glass fiber and wire meshes of aluminum were produced. Tensile, bending, and hardness tests were performed to investigate how inserting Al wire meshes through thickness of the specimen in place of glass fiber layers affected the material mechanical characteristics. The characteristics of the generated hybrid laminates represented by strength and ductility were greatly influenced by varying the position and orienting direction of the aluminum wire mesh ply. Inclusion of Al wire mesh in the outer layers significantly causes deterioration in material tensile and bending strengths. The tensile strain as well as bending strain, on the other hand, were improved as a result of incorporating Al wire meshes by 51.3 percent and 153.4 percent, respectively. [ABSTRACT FROM AUTHOR]

The Fe/Ni-based coatings fabricated by high power diode laser (HPDL) cladding (expressed as laser clad layers) were used as the renovated or modified layers formed on a 4Cr5MoSiV1 steel substrate. The laser clad layers with high strength ceramic particles were prepared on the steel by means of an industrial set up so as to improve the mechanical and tribological properties of the metal substrate. The microstructure and phase constituents, as well as microhardness and wear properties of the laser clad layers were analysed in detail. The carbides or ceramic phases were dispersed within grains for Fe/Ni based clad layer. Especially, the two kinds of Ni/Fe based clad layers containing WC particles present excellent properties combined with a high hardness and a good dry friction wear and impact abrasive wear resistance, greatly prolonging the service life of metal components. These laser clad layers were widely used in electric power industry, such as steam turbines, hydroturbine, boiler tube, valve body in power station. In addition, the laser clad layers have been used for the metal component in the coal and mining industries. [ABSTRACT FROM AUTHOR]

This article aimed to analyze the effect of the thermal oxidation in the corrosion resistance and the hardness properties of TiO2 nanostructures obtained by the anodizing process in the HF/H3PO4 solution. TiO2 nanostructures on Ti6Al4V obtained by anodizing processes were subjected to thermal oxidation (TO) treatments over a temperature range from 500 ºC to 620 ºC for 2 hours. Surface morphology was evaluated by using scanning electron microscopy; the hardness properties of TiO2 nanostructures were obtained by Nanoindentation measurements using a Berkovich probe with a tip radius of 150 mm. The corrosion behavior of the samples was studied using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that TiO2 nanostructures, modified by thermal oxidation, increased the surface properties of hardness and corrosion resistance, compared to the substrate, maintaining its mixed or tubular structure. On the other hand, a transformation of nanotubes to nanopores after 600ºC was evidenced, generating significant changes in the mechanical properties of these structures. [ABSTRACT FROM AUTHOR]

Transition metal carbides (TMC) exhibit a range of exceptional features. However, the poor oxidation resistance of TMC derivatives generally limits their industrial applications at medium-high temperatures. The problem statement relates how the elastic properties of TMC can be enhanced through nitrogen addition and how our approach can fill the gap of earlier computational works, which biasedly assumed TMCN crystals remain unchanged in cubic form. Genetic algorithm aided crystal structure screening and ab initio computations of the structural, electronic and mechanical properties of TMC-TMN and TMC-N 2 alloys containing different N contents have been performed. The calculations produced an experimentally verified Zr 2 CN phase and four previously unreported metallic compounds, namely the Zr 4 C 3 N (I4/mmm), Zr 6 C 4 N 2 (Immm), Zr 4 CN 3 (Pm 3 ‾ m) and Zr 2 C 2 N 4 (Amm2). Phase stabilities of HfC x N 1- x and HfC-N 2 were also evaluated, with the latter anomalously showing semiconducting behavior. Ground-state properties such as lattice constants and simulated XRD were analyzed and compared with experimental literature wherever possible. The predicted formation energies and lattice dynamics investigation indicate that all studied alloys are energetically and dynamically stable even at 0 K in the whole concentration range. Analyses of the calculated elastic parameters and relevant moduli show that these phases have sufficient mechanical stability, superior melting temperature, improved Vickers hardness ~30 GPa compared to their carbides and fracture toughness of ~4.0 MPa m1/2, which is comparable to most transition metal borides. Particularly, elastic moduli and fracture toughness of Zr–C–N are increasing monotonically with N-content. Further check on density of states, metallicity, Bader charge and electron localization function (ELF) demonstrate the presence of strong covalent with mild ionic and metallic bonds in all studied structures. [ABSTRACT FROM AUTHOR]

Copyright of Journal of University of Anbar for Pure Science is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Materials & Technologies / Materiali in Tehnologije is the property of Institute of Metals & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Transparent alumina was fabricated from untreated commercial powder by high-pressure spark plasma sintering (HPSPS) at temperatures of 1000, 1050 and 1100 °C under pressures of 250-800 MPa. It was established that transparency strongly depends on the HPSPS parameters. At all temperatures, there was a certain point when increasing the pressure led to decreasing transparency. At 1100 °C, relatively high pressure led to excessive grain growth, as well as the formation of creep-induced porosity at the center of the samples. Hardness values decreased with pressure due to grain growth, correlated with the Hall-Petch relationship. The optimal combination of optical and mechanical properties (68% in-line transmittance at a wavelength of 640 nm and a hardness value of about 2300 HV2) was achieved after sintering at 1050 °C under 600 MPa. [ABSTRACT FROM AUTHOR]

In the present study, dissimilar weld joint was prepared using the P91 and P92 steel plate of 8-mm thickness, using the multi-pass gas tungsten arc (GTA) welding with filler (weld 1) and autogenous tungsten inert gas welding (A-TIG) process (weld 2). Evolution of δ-ferrite patches was studied in weld zone and heat affected zone (HAZ) for both weld 1 and weld 2. Effect of varying post weld heat treatment (PWHT) duration was also studied on δ-ferrite patches and mechanical properties of the dissimilar weld joint. PWHT was carried out at 760°C. For weld 2, weld zone showed poor impact toughness and higher peak hardness as compared to weld 1. After the PWHT, a considerable reduction in hardness was obtained for both weld 1 and weld 2,while impact toughness of weld zone showed a continuous increment with PWHT duration. For weldments characterisation, optical microscope, scanning electron microscope (SEM) and microhardness tester were utilised. [ABSTRACT FROM AUTHOR]

Abstract The mechanical parameters such as elastic moduli E and shear moduli G of second phases are critical inputs for modeling and optimizing mechanical properties of aluminum alloys. However, some of these mechanical parameters are lacking because these micron or even nano scale phases are hard to be tested. The aim of this paper is to present an efficient approach to test the mechanical properties of second phases in aluminum alloys accurately. The α-AlFeSi, β-AlFeSi and Mg 2 Si particles at the millimeter scale were prepared by directional solidification with the aid of calculation of phase diagrams (CALPHAD). Such a large size can effectively reduce the impact of particle penetration into matrix in nanoindentation and Vickers hardness experiments. The elastic moduli of α-AlFeSi, β-AlFeSi and Mg 2 Si were determined as 183.81 ± 8.64 GPa, 174.13 ± 6.81 GPa and 116.38 ± 4.06 GPa, respectively, and their Vickers hardness values were 883 ± 64, 765 ± 21 and 475 ± 22 HV, respectively. Besides, the continuous uniform plastic deformation (without pop-in phenomenon in load-displacement curve) of Mg 2 Si was observed and is attributed to the anti fluorite structure of Mg 2 Si. Further, by Vickers hardness and electron backscatter diffraction (EBSD) it was found that the hexagonal α-AlFeSi had greater hardness anisotropy than the near-tetragonal β-AlFeSi. Overall, the hardness values of α-AlFeSi particles in < u 0 u ¯ w > direction were higher than others, the hardness values of β-AlFeSi particles near <001> were lower than others. Highlights • Millimeter scale α-AlFeSi, β-AlFeSi and Mg 2 Si particles were prepared. • Mechanical properties of α-AlFeSi, β-AlFeSi and Mg 2 Si were determined. • Mg 2 Si shows continuous uniform plastic deformation under the nanoindentation. • The anisotropy of α-AlFeSi and β-AlFeSi were investigated. [ABSTRACT FROM AUTHOR]

Abstract A multiscale investigation of the microstructures and mechanical properties of Inconel 718 fabricated by selective laser melting (SLM) was performed on the as-SLM and heat-treated (HT) samples at various build locations. The microstructures were characterized by optical microscopy, high-resolution scanning electron microscopy, and electron backscatter diffraction over a wide range of length-scales. The as-SLM samples exhibited unique multi-scale microstructure features, including a few hundred-micrometer melt pools and columnar cube-textured grains, micrometer-sized dendritic and cellular sub-grain structures from chemical segregation and precipitates. Upon heat treatment, recrystallization occurred in the sample, replacing the unique SLM microstructures with homogenized grains, annealing twins, and nano-scale precipitates. Dry sliding wear tests, Vickers hardness tests, and force modulation microscopy in the atomic force microscopy were conducted to characterize the mechanical properties of the SLM parts. It was found that the wear resistance of the as-SLM sample was sensitive to the grain-level structures, exhibiting a relatively large spatial variation (∼11%) at different build locations. In contrast, the Vickers hardness barely changed (<1%) with locations. Heat treatment reduced the wear rate from 7.2 × 10−4 to 5.83 × 10−4 mm3/Nm and enhanced the hardness from 320 to 458 HV, resulting from the precipitation of nanoscale strengthening phases resolved from force modulation microscopy. Finally, the correlations of the mechanical properties with the hierarchical SLM microstructures were discussed, implying the importance of multi-scale conditions on tuning the SLM part performance. Highlights • IN 718 fabricated by SLM shows hierarchical and heterogeneous microstructure. • Hardness is not sensitive to heterogeneity, barely changed with locations. • Wear resistance exhibits large spatial variation due to SLM grain structure. • Chemical segregation in the grain leads to nanoscale mechanical fluctuation. [ABSTRACT FROM AUTHOR]

Cold work tool steels are used for punching, cutting, forming, cold forging, cold extrusion, cold rolling, etc. Those steels have higher hard phases like carbides and plate martensite compared to other steel alloys, but the everlasting challenge is the enough strength to toughness relation, without immediate fracture. Carbides provide the wear resistance, acting as hard precipitates inside the structure of steels. Variation in size and fraction of carbides, depending on manufacturing route, alloy content, hot working and heat treatment, will give the tool steel the desired mechanical properties. However, conventional cast tooling is the major production route used, which could be followed by a process called electro slag refining where not only the nonmetallic inclusion content is lowered but also the texture of steel is modified. Conventional casting of tool and die steels has a lower production cost per unit than the conventional processing routes. The disadvantage though is a more heterogeneous material, due to segregation of primary or leduburitic carbide net cells. Experimental trials were made to control the distribution and morphology of primary carbides in the matrix of martensite by spheroidizing them through molten metal treatment by using FeSiMgRe ferroalloy additions and heat treatment processes. Types and distributions of different carbides in the matrix of cast D2-steel were detected using X-ray diffraction and SEM/EDX units. Series of carbides like (FeCr)7C3, (FeCr)3C and (FeCr)4C were detected. In all cases, the optimum tempering conditions were found to be (300 °C, 5 h, air cooling), which in turn insured hardness of about 59–63HRC for cast AISI-D2 steel. The fracture index for that hard matrix was Kic = 70–60 MPa √m, and impact energy = 54–35 J was achieved. [ABSTRACT FROM AUTHOR]

Abstract Zirconium carbide (ZrC x) is an important structural material. Its high strength and hardness makes it suitable for application in hard materials and non-oxide type new ceramics. Hence, several researches have been carried out with the aim of understanding its mechanical properties. In this paper, the mechanical properties of ZrC x (0.45 ≤ x ≤ 0.72) were investigated considering the grain size effect. The bending strength as a function of grain size obeyed the Hall–Petch relation. The composition dependence of the strength linearly decreased with decreasing carbon content, followed by saturation at x = 0.6, corresponding to the lowest x value of the ZrC x single phase region. The Young's modulus and hardness monotonically decreased with decreasing carbon content, independently of grain size. The annealing of ZrC 0.45 at 1273 K for 18 ks led to the formation of Zr precipitates, which showed an orientation relationship with the ZrC matrix of (0001) Zr //(111) ZrC. These precipitations formed compressive residual stress in the ZrC phase, resulting in an 80% increase in the bending strength after annealing. Graphical abstract fx1 Highlights • Effect of composition and grain size on mechanical properties of ZrC x investigated. • Bending strength obeyed the Hall–Petch relation. • Young's modulus and hardness were independent of grain size. • Young's modulus and hardness monotonically decreased with decreasing carbon content. • Annealing of ZrC 0.45 formed coherent Zr precipitates, improving bending strength. [ABSTRACT FROM AUTHOR]

The mechanical properties, corrosion resistance and microstructure of the spray-formed 7075 alloy after one-stage aging treatments were studied by using a tensile tester, hardness tester, slow strain rate test, electrical test, intergranular corrosion test, electrochemical corrosion test, scanning electron microscope and transmission electron microscope. The results show that the strength and hardness of the alloy have double peaks with the one-stage aging treatments. With aging at 120 °C for 24 h (first peak), abundant tiny η′ phases and η phases precipitate in the matrix. The tensile strength of the alloy increases to 760 MPa, and the elongation is 4.8%. After aging at 120 °C for 132 h (second peak), blocky η phases appear. The tensile strength and elongation of the alloy are 757 MPa and 5.9%, respectively. The grain boundary precipitates dissociate, and the precipitate-free zones are widened. The corrosion resistance of the alloy increases. [ABSTRACT FROM AUTHOR]

Abstract TiAlSiCN coatings were deposited by radio frequency reactive magnetron co-sputtering. In the coatings, the Si content is tuned by using targets with different Si additions. The structures and mechanical properties of the TiAlSiCN coatings were strongly depended on the Si content. The Si ~3 at.% sample exhibits the highest hardness of 38 GPa among the coatings prepared in this work. The nanocomposite microstructure containing B1-TiN nanocrystals with C:N ≈ 1:1 and combined C, SiN x and SiC x amorphous phases is attributed to the enhanced hardness. Highlights • Mechanical properties and structure of TiAlSiCN are sensitive to Si addition. • TiAlSiCN coating with small Si addition shows a high hardness of 3650 HV. • Nanocomposite structure is obtained in TiAlSiCN coatings. [ABSTRACT FROM AUTHOR]

Abstract The synergistic effects of the initial microstructure and the intercritical annealing time on the microstructure and tensile properties of low carbon steel were studied. It was found that by refining the pre-intercritical annealing microstructure, the resulting duplex DP microstructure becomes finer, which results in the enhancement of the tensile properties and work-hardening behavior. Based on the hardness measurements, three stages were identified for intercritical annealing: initial rise or fall, reaching a plateau, and final fall to a low value. The pre-intercritical annealing microstructure did not show any pronounced effects on these stages, with the exception of the short-lived initial stage. It was shown that the DP steel obtained right after reaching the abovementioned plateau can exhibit improved mechanical properties and work-hardening behavior. During the third stage, the enrichment of manganese in austenite and the concurrent grain growth were found to be the main factors taking part in the change of hardness and tensile strength and reappearance of the yield-point elongation. The impact of the microstructural features (austenite and ferrite) on the grain growth behavior during intercritical annealing and the effect of the grain size on the Lüders strain were also discussed. [ABSTRACT FROM AUTHOR]

Owing to heterogeneous nucleation at the melt‐crucible interface, it is difficult to access the dynamic and physical properties of supercooled liquids of poor glass formers when using a conventional melting technique. To avoid the interface nucleation, we apply a containerless aerodynamic levitation laser‐melting technique to measure the viscosity, density, and surface tension of a poor glass‐forming system, ie, the mixed alkaline‐earth aluminate melts. The temperature and composition (Ca/Sr) dependence of thermal‐physical properties are investigated on both thermodynamically stable and metastable supercooled melts. In addition, the levitation laser‐melting technique is used to quench the melts to glasses, and then the mixed alkaline‐earth effects are investigated on Vickers micro‐hardness and glass transition temperatures. By comparing the chosen silicate and aluminate series, we have identified weaker mixed alkaline‐earth effects in aluminate series than those in silicate series, and this difference could be attributed to the different structural roles of alkaline‐earth elements in two glass series. [ABSTRACT FROM AUTHOR]

Abstract The mechanical of the tricalcium phosphate matrix sintered with different amounts of the magnesium oxide have been investigated. The tricalcium phosphate - magnesium oxide composites were characterized by using the mechanical properties such as rupture strength, Vickers hardness and elastic modulus. The effects of the sintering process on the structural changes of the composites were investigated. At 1300 °C, the highest performance was obtained for the tricalcium phosphate containing 5 wt% MgO. The maximum mechanical strength and Young's modulus of the composites reached 9 MPa and 38 GPa, respectively. The result can be explained by the formation of both, liquid phase, which helps to fill the pores in the microstructure, and a new phase relative to the calcium magnesium phosphate. At 1400 °C and beyond 5 wt% MgO, the performances of the composites are hindered by the intragranular porosity formation and by the exaggerated grain growth. The addition of the magnesium oxide to the tricalcium phosphate matrix promotes the reduction of the wear rate and the friction coefficient. The composites performances are close to the enamel. Highlights • We measure the mechanical and tribological properties of bioceramics. • We characterize the effect of MgO on the performances of the tricalcium phosphate. • MgO increases the performances of the tricalcium phosphate. [ABSTRACT FROM AUTHOR]

Abstract Twelve different equiatomic five-metal carbides of group IVB, VB, and VIB refractory transition metals are synthesized via high-energy ball milling and spark plasma sintering. Implementation of a newly developed ab initio entropy descriptor aids in selection of candidate compositions for synthesis of high entropy and entropy stabilized carbides. Phase formation and composition uniformity are analyzed via XRD, EDS, S/TEM-EDS, and EXAFS. Nine of the twelve candidates form true single-phase materials with the rocksalt (B1) structure when sintered at 2473 K and can therefore be investigated as high entropy carbides (HECs). The composition (V 0.2 Nb 0.2 Ta 0.2 Mo 0.2 W 0.2)C is presented as a likely candidate for further investigation as an entropy stabilized carbide. Seven of the carbides are examined for mechanical properties via nanoindentation. The HECs show significantly enhanced hardness when compared to a rule of mixtures average of the constituent binary carbides and to the highest hardness of the binary constituents. The mechanical properties are correlated to the electronic structure of the solid solutions, offering a future route to tunability of the mechanical properties of carbide ceramics via exploration of a new complex composition space. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Abstract This study investigated the effect of oxygen doping on the crystalline structure, microstructure, and selected mechanical properties (Vickers microhardness, Young's modulus and internal friction) of Ti-15Zr-xMo (x = 5, 7.5, 10, 15 and 20 wt%) alloys for use as biomaterials. The monitoring of oxygen pressure along with the doping treatment indicated that the interstitial element was successfully absorbed into the samples. Results showed that oxygen content slightly altered the α"/β phase proportion and β phase crystalline parameter without abruptly changing their microstructure. Moreover, the selected mechanical properties suffered variations in a non-linear manner. Oxygen content was found to be suitable to produce small variations in the microstructure and in the selected properties of biomedical Ti alloys, keeping the main composition unchanged. Highlights • Interstitial oxygen atoms were inserted into the samples by doping treatment. • Crystalline structure and microstructure slightly changed with the oxygen content. • Selected mechanical properties were altered by the oxygen in a non-linear way. • Oxygen changed the mechanical properties remaining the main composition unchanged. [ABSTRACT FROM AUTHOR]

Abstract Aluminium matrix hybrid composites (AMHCs) containing 30 wt % Y 2 W 3 O 12 - (0, 5, 10, 15 wt %) AlN and 30 wt % AlN - (0, 5, 10, 15 wt %) Y 2 W 3 O 12 , defined as Y 2 W 3 O 12 and AlN rich composites, respectively, were prepared by high energy ball milling followed by compaction, sintering and forging. The hardness, compressive strength, coefficient of thermal expansion (CTE), thermal conductivity and thermal stability of all the composites were evaluated. A high compressive strength (500–520 MPa) along with a low CTE (12–14 × 10−6 K−1) is achievable in such hybrid composites by adjusting the amount of individual reinforcement. The thermal cycling experiments suggest that the composites are thermally stable. The thermal conductivity of the Y 2 W 3 O 12 rich composites increases with an addition of AlN, whereas it decreases in the AlN rich composites with an addition of Y 2 W 3 O 12. Highlights • Aluminium matrix hybrid composite (AMHC) containing AlN and Y 2 W 3 O 12 were synthesized by powder metallurgy route. • Mechanical properties of AHMC improved with an addition of the AlN. • Coefficient of thermal expansion decreased with an addition of the Y 2 W 3 O 12. • Thermal cycling suggested thermal stability of AHMC. • Experimental CTE value was good agreement with the value predicted by Kerner's Model. [ABSTRACT FROM AUTHOR]

Abstract The overlapping friction taper plug welding (FTPW) process influences the overlapped welds and bonding quality of the friction stitch weld, therefore, flaws, microstructure and hardness evolutions were observed with the progress of overlapping FTPW process in a simulated wet condition to study the forming mechanism of underwater friction stitch welding. DH36 plugs were used to repair the arc welded DH36 joint. Six burn-off distances (namely consumptions) of plug were chosen to observe the intermediate status of flaws, microstructure and hardness. With the increase in burn-off distance, bonding was firstly formed at the bottom, then at the sidewall and finally at the rounded corner. In the overlapping FTPW process, the microstructure was coarse lath martensite and hardness up to 410 HV 10 in the center of stir zone while acicular ferrite and grain boundary ferrite with hardness from 290 to 320 HV 10 was observed at the rounded corner of stir zone; fine lath martensite was observed and hardness was about 370 HV 10 in the forged zone in upper part of the overlapping friction taper plug weld; the overlapped friction taper plug welds were tempered and the hardness was reduced with a minimum about 250 HV 10. The overlapping FTPW process study shows increase in heat input at the location of flaws at the beginning of the process, improving material flow at the location of flaws, and good plug material selection will promote the weld quality in underwater friction stitch welding. [ABSTRACT FROM AUTHOR]

Abstract In this study, the effect of processing parameters in directed energy deposition (DED) additive manufacturing (AM) on the microstructure and mechanical properties of Ti-6Al-4V was evaluated. A commercial DED system was used to deposit square patches of Ti-6Al-4V onto a substrate with the same nominal composition, with varying conditions to represent those that may be found in actual repair applications. A design of experiments was used to study the effect of substrate thickness, interlayer dwell time (time between deposition of subsequent layers), initial substrate temperature, hatch pattern, and number of deposited layers on the microstructure, porosity, and hardness of the deposition. Varying these processing parameters elucidates how each independently, or all collectively, impact the resulting microstructure and properties of Ti-6Al-4V deposits. As internal pores, or defects, significantly affect the properties of additively manufactured components, this study aimed to identify and quantify those defects in DED. The results from the current study show that with decreasing substrate thickness, the depth of the heat affected zone increased by an average of 400 μm. The density of the part was affected by the number of deposited layers and the initial substrate temperature, increasing with increasing the number of deposited layers, but decreasing with higher initial substrate temperatures. Lastly, the hardness increased with increasing substrate thickness, but was not impacted significantly by the other parameters studied. [ABSTRACT FROM AUTHOR]

The microstructures, phase composition, and mechanical properties of the CoCrFeNi2Al1-xWx (x: molar ratio, x=0,0.1,0.2, and 0.3) high entropy alloys were investigated. Only BCC phase and FCC phase were found in CoCrFeNi2Al1-xWx alloys. Thereinto, the CoCrFeNi2Al alloy was comprised of the primary phase with BCC structure and the eutectic structures with BCC and FCC phases. The CoCrFeNi2Al0.9W0.1, CoCrFeNi2Al0.8W0.2, and CoCrFeNi2Al0.7W0.3 alloys were comprised of the primary phase with FCC structure and the eutectic structures with BCC and FCC phases. The main effect of Al element on CoCrFeNi2Al1-xWx alloys was tailoring the proportion of BCC phase and FCC phase, while W element played a greater role than Al element in the solid solution strengthening effect. Hence, the mechanical properties of AlCoCrFeNi2 alloy can be tailored by adjusting the concentration of Al and W elements to obtain a wider range of applications. [ABSTRACT FROM AUTHOR]

Abstract The case hardening process (carburizing followed by quenching to room temperature) is one of the heat treatments routinely conducted in various industrial sectors. Depending on the parameters applied during the post-carburizing stage, different microstructural constituents may develop in the interior (core) section of a case-hardened component which substantially influence the overall mechanical properties. In the present work, the effects of different heat treatments following the carburizing stage on the core microstructure evolution, the resulting toughness and hardness properties were investigated. The heat treatments were carried out employing Navy C-ring specimens, the core of which were used for microstructural investigations and fabrication of mini-Charpy specimens. Besides, nanoindentation tests were also carried out in the same region to examine the local hardness of different constituents. Furthermore, the microstructural evolutions were also studied utilizing multi-phase field modeling. Based on the obtained results, it can be shown that the increase in fractions of bainite and retained austenite is in direct correlation with the impact toughness improvement, however, the increase in fraction of ferrite and martensite acts inversely. Moreover, despite the differences in fractions of constituents, the level of overall hardness is similar in all the developed microstructures. Additionally, the nanoindentation results revealed that the formation of large fraction of bainitic ferrite leads to high level of scattering in nanohardness of martensite. Phase field simulations show that this is attributed to the degree of carbon partitioning into the adjacent austenitic area where depending on the local morphology and size can be quite different. [ABSTRACT FROM AUTHOR]

Abstract The presence of small-scale precipitation is known to contribute to the high hardness and yield strength due to their hardening effect, which is widely applied in various engineering materials. The long period stacking ordered (LPSO) structure phases as well as stacking faults (SFs) are expected to play an important role in tuning the mechanical properties of Mg alloy. However, we found that the hardness and strength could not benefit from the lamellar LPSO structures and SFs precipitated in the matrix. Using transmission electron microscopy(TEM), high resolution transmission electron microscopy (HRTEM) and so on, we directly illustrate that the weak hardening effect is corresponding to the limited resistance of these basal precipitates in blocking the basal dislocation slip and the weaker solution strengthening of the matrix as the result of that much solute atoms have get into the precipitations. This finding demonstrates that the shape of the precipitations and their orientation relation to the glide planes of dislocation as well as the distribution of solute atoms are considerable factors to the strengthening effect. [ABSTRACT FROM AUTHOR]

Highlights • Hardness of the films increases with increasing compressive macrostress. • Films with high ratio H/E∗ ≥ 0.10 exhibit an enhanced resistance to cracking. • Films sputtered at a high energy E bi > 3 MJ/cm3 dense, voids-free microstructure. Abstract The article reports on the influence of a compressive macrostress σ in the Ti(Al,V)N films on their mechanical properties, structure, microstructure, and resistance to cracking. The macrostress σ is controlled by the energy E bi delivered into the growing film by bombarding ions. The Ti(Al,V)N films were sputtered by a dual magnetron with closed magnetic field. It is shown that (1) the compressive macrostress (σ < 0) increases the hardness H of the film and the ratio H/E∗, (2) the films exhibits a dense, voids-free, non-columnar microstructure in the case when the energy E bi ≥ 3 MJ/cm3, (3) the enhanced resistance to cracking of the films is controlled by its mechanical properties, microstructure and macrostress σ; here E∗ is the effective Young's modulus. [ABSTRACT FROM AUTHOR]

Abstract The vitreous enamel coatings present very interesting properties for several industrial applications due to the glassy nature of the matter. Their chemical resistance and corrosion protection properties result very high due to the glassy nature of deposits. A good wear behavior is also requested in some applications. The use of composite layer obtained by the addition of hard particles to enamel could be a possible solution to increase the deposits hardness. In literature, there are some work about the chemical nature of the added particles, but the influence of the dimension and quantity of these particles are not well studied. The aim of this work is the study of composite enamel layers deposited on low carbon steel substrate with addition of Al 2 O 3 particles characterized by macro and micro dimensions with different concentration (5, 10 and 20 wt.%). After the microstructure characterization, the abrasion resistance behavior is evaluated by Taber Test following ASTM C501 for 1500 cycles. Mass loss, gloss and roughness changes are collected. The protection properties change is evaluated by Electrochemical Impedance Spectroscopy measurements. The addition of micro dimension particles produces the best behavior. On the contrary, the presence of macro dimension particles reduces the abrasion resistance, probably caused by the increase of porosity level during firing treatment. Finally, the corrosion protection properties are evaluated by Kesternich test (aggressive fog with the presence of SO 2), simulating an industrial environment. In this case the presence of the micro- particles shows a limited resistance. Probably the presence of the particles produces an increase of surface roughness and a presence of higher quantity of particles in surface, which favor the start of enamel degradation with a loss of protection properties. Increasing the quantity of particles, a reduction of chemical resistance is observed. Highlights • Enamel coatings present high corrosion protection properties. • Corundum particles could improve abrasion resistance. • The particle dimension and concentration are a crucial aspect. • Kesternich test simulates an aggressive environment. • Taber test evaluates the coatings' resistance. [ABSTRACT FROM AUTHOR]

Abstract Ti-5553 and related alloys are known as important structural alloys in the aircraft industry. In this work, the effect of double aging heat-treatments on the phase transformations and mechanical behavior of an Nb-modified Ti-5553 alloy (Ti-12Nb-5Al-5V-3Cr-0.5Fe wt%) was investigated by X-ray diffraction, scanning, and transmission electron microscopy. Results show the phase transformation sequence is altered with the time spent at the first aging stage. After 3 h at 350 °C, isothermal ω-phase is extensively formed throughout the β-matrix, while after 8 h, α-phase embryos were detected. The first stages of α-phase formation in the modified alloy seem to be influenced both by the presence of ω particles and low-angle grain boundaries. Microstructures resultant of the first stages of aging change the response to the second stage, performed at 525 °C and 600 °C, for 2 h. The final microstructure obtained for the modified alloy (Ti-12Nb) after the second stage of aging diverge from the original Ti-5553 alloy subjected to the same heat-treatment. Finally, tensile and compression tests indicate Ti-12Nb is a viable substitute for Ti-5553, with comparable strength and slightly lower ductility after double aging. Graphical abstract fx1 [ABSTRACT FROM AUTHOR]

Abstract Cu–Cr alloys have been widely used in industrial applications owing to their good combination of mechanical properties and electrical conductivity. However, the comprehensive performance of the alloy needs to be further improved to meet the harsh working environment. Hence, in this study, a new type of Cu–Cr alloy with Co and Si additions together with cryogenic rolling (CR) was designed and investigated. Microstructure analysis confirms that the Cr 15 Co 9 Si 6 and Co 2 Si phases are formed with Co and Si additions into the Cu–Cr alloy. For the more, partial Cr 15 Co 9 Si 6 phase decomposes during heat treatment process, and the Co 2 Si and Cr precipitates are precipitated from matrix during aging process. The improvement of tensile properties of the Cu–1Cr–1Co–0.6Si alloy is mainly attributed to the precipitation strengthening and grain boundary strengthening, and is also benefited from dislocation density strengthening, twin boundary strengthening, and solid solution strengthening. The electrical conductivity of the Cu–1Cr–1Co–0.6Si alloy decreases dramatically mainly due to the increase of impurity scattering caused by surplus Si atoms. CR deformation is helpful for more solute atoms precipitated from the supersaturated solid solution during aging process, and thus the electrical conductivity of the Cu–1Cr–1Co–0.6Si alloy increases with increasing deformation amount. After homogenizing treatment at 900 °C for 2 h, hot rolling by 60% at 900 °C, solution treating at 990 °C for 4 h, cold rolling by 90%, and aging at 440 °C for 1 h, the hardness, yield strength (YS), ultimate tensile strength (UTS), and electrical conductivity of the Cu–1Cr–1Co–0.6Si alloy are 214.6 HV, 663.7 MPa, 745.9 MPa and 41.6%IACS, respectively, which exhibit good mechanical properties with a proper electrical conductivity. These results provide a feasible route for developing high performance Cu–Cr alloys. [ABSTRACT FROM AUTHOR]

Abstract An autogenous gas tungsten arc welded P92 weld joint was subjected to two different post weld heat treatment (PWHT). One PWHT involved tempering of the as-welded sample at 760 °C for 2 h (referred to as PWDT) followed by natural air cooling. The other PWHT involved normalizing (re-austenitizing) the as-welded sample at 1040 °C for 40 min followed by PWDT (referred as PWNT). The cross-section of the as-welded sample exhibited a higher degree of microstructural heterogeneity. Both the PWDT and PWNT heat treatment procedures reduced the heterogeneity gradient along the weld cross section. The heat affected zone (HAZ) of the as-welded and PWDT samples showed Charpy toughness values of 3 ± 4 J and 64 ± 6 J, respectively, which were lower than that of the base metal (72 ± 5 J). The PWNT treated sample exhibited a HAZ Charpy toughness value of 83 ± 4 J which was higher than that of the base metal. The brittle mode of the fracture with river patterns was observed for the as-welded and PWDT treated sample while a ductile mode of fracture with fine and shallow dimples was observed for the PWNT condition. The PWNT treatment resulted in dissolution of the ferrite patches and formation of a uniform microstructure along the weld cross section. The PWNT treated samples exhibited the lowest yield strength to tensile strength ratio supporting the enhanced ductility as a result of this re-austenizing heat treatment. The as-welded and PWDT treated weld joints showed the presence of detrimental δ ferrite phase in the weld fusion zone and the coarse grained heat affected zone. The PWNT completely removed the δ ferrite patches from the microstructure whereas the PWDT treatment merely reduced the range of the hardness of the δ ferrite from 179 to 301 HV (as welded) to 204–228 HV. [ABSTRACT FROM AUTHOR]

Abstract Embrittlement of the 2205DSS base metal occurred at 500 °C, 700 °C, and 800 °C as the “475 °C embrittlement” and precipitation of the σ phase. The high-hardness quenched martensite in the as-welded welding seam became low-hardness tempered martensite at 500 °C and 600 °C. It contributed to the improved toughness of the welded specimen at 500 °C and 600 °C. The toughness of the welded specimen decreased at 700 °C and 800 °C because of the generation of high-hardness normalized martensite. A carbon-depleted layer and carbon-rich layer formed on the welding seam-Q235 interface following post-weld heat treatment because of the diffusion of carbon atoms. A carbon-depleted layer and carbon-rich layer formed at 600 °C, 700 °C, and 800 °C. The thickest carbon-depleted layer was obtained at 700 °C, as the fastest diffusion of carbon atoms occurred in the Q235 BM. The ferrite grain of the carbon-depleted layer also rapidly coarsened owing to the lack of a hindering effect from Fe 3 C on the grain boundary migration. The optimal post-weld heat treatment temperature was determined to be 600 °C. [ABSTRACT FROM AUTHOR]

High-entropy alloys (HEAs) have become a research hotspot in recent years. The nature of the multi-principal elements, high mixing entropy, and mutual interactions between elements render this novel material outstanding mechanical and functional properties, in which most research efforts are focused on mechanical properties. There are many aspects that can influence the mechanical behavior, such as constituent elements and fabrication methods. This paper will mainly summarize and discuss the effects of constituent elements and fabrication techniques on the mechanical properties of HEAs, by reviewing relevant papers, to have a better understanding of the variation ranges resulting from the above two factors and the reasons for the properties changes. Future directions are provided at the end of this article. [ABSTRACT FROM AUTHOR]

The aging kinetics, the mechanical properties, and the structure of cast alloy IMV7-1 of the Mg - Y - Gd - Zr system alloyed additionally with dysprosium are studied. It is shown that yttrium and gadolinium may be replaced partially with dysprosium without changes in the aging kinetics and lowering the hardening and the level of the mechanical properties of alloy IMV7-1. [ABSTRACT FROM AUTHOR]

Steel bearings have plenty of usages in manufacturing different kinds of ball bearings, bearings and cold rolling rollers. Heat treatment has an important role in the properties of this group of steels. Therefore, in current research the effect of tempering temperature on the microstructure, hardness, impact energy and wear resistance in forged steel containing Chrome, Manganese and Molybdenum will be studied. For this purpose, the samples were tempered after austenitizing at 900°C and quenching in the oil at 6 temperatures of 150, 250, 350, 450, 550 and 650 °C for an hour. Then microstructural studies and mechanical properties of the samples including hardness, impact energy and wear resistance were surveyed on the samples. The results showed that the hardness was gradually decreased (impact energy gradually increased) at the temperature range of 150 - 250 °C and at temperature range of 350 - 650°C, the hardness would decrease and the impact energy would increase. Also, the wear resistance would decrease with an increase in the tempering temperature. The result should be justified considering the softening of the structure and the reduction in martensite tetragonality which stems from an increase in the tempering temperature. The study of the wear surface of the samples indicated that the dominant wear mechanism was adhesive wear in which with an increase the tempering temperature due to a reduction in the hardness of the samples, more sever adhesive wear was observed. [ABSTRACT FROM AUTHOR]