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Pyrometallurgical remnants, including slags and technical ceramics, offer crucial insights into Early Medieval ironworking. Iron held substantial economic significance during this era and its processing is particularly evident in settlement agglomerations and proto-urban sites across Northern and East Central Europe. Despite its importance, large-scale ironworking remains inadequately explored within broader socio-economic contexts. Our study examines around 300 kg of pyrotechnical waste from the northern suburbium of the Mikulčice-Valy settlement agglomeration (Czech Republic) using macroscopic and metallographic (SEM-EDS, WD-XRF) methods. The findings reveal specialised blacksmithing characterised by intensity and diversity contributing to a better understanding of the operational dynamics and installations in craft-production workshops. We propose that blacksmiths capitalised on the proto-urban environment, satisfying a high demand for diverse iron commodities of a dense population actively engaged in household, agricultural and artisanal work. While elites facilitated access to raw materials and maintained relative peace, direct control over iron production and distribution among the elites appears limited, apart from valuables like weapons. This study sheds light on the complex interplay between ironworkers and political-economic structures, offering new perspectives on the mechanisms driving Early Medieval iron economies. [ABSTRACT FROM AUTHOR]

One of the most frequent causes of coal fired power plant shutdown is boiler tube leak. Superheaters are crucial components of boilers operating under high temperatures and pressures. Understanding the superheater potential damages is essential to define the rectification action needed to keep and elevate overall power plant productivity. This paper highlights the analysis of platen superheater tube failure in a 2x150 MW coal-fired power plant in South Sumatera. Various test including chemical composition, hardness, tensile, metallography, SEM fracture surface examination, and XRD compound analysis were conducted for investigation purposed. The failure was initiated by the plugging of the tube elbow due to deposits and ashes adhering to the tube's interior. This obstruction prevented saturated steam flow inside the tube, leading to overheating and a subsequent drop in mechanical strength. Overheating was confirmed by the presence of spheroid particles in the ferrite matrix. Prolonged overheating resulted in the formation of microvoids, leading to creep failure and crack formation in the tube. The improvements made by adding refractory material give positive results. The platen superheater tubes which previously exceeded temperature limits, currently operate within normal range temperatures, reduced spray water consumption 6-10 tons/day, and significantly increased boiler efficiency from 83.19% to 83.54%. [ABSTRACT FROM AUTHOR]

The microstructure and mechanical characteristics of the AZ61 magnesium alloy with varying RE (RE) content during the extrusion-forging process were thoroughly examined using metallography, SEM, EDS, and XRD. Findings indicate that as the RE content increases, the β-Mg17Al12 phase is significantly diminished, primarily resulting in a microstructure composed of Al4Ce and Al8Mn4Ce phases or Al3Nd and Al4Ce phases, along with a minor presence of Al4La phase, which appears in black granular or agglomerated forms along the extrusion axis. Following die forging, the RE phases in the AZ61+xRE Mg alloy's microstructure experienced secondary fragmentation due to triaxial compressive stress, leading to a drum-shaped or S-shaped distribution of the fractured RE material, without any spheroidization or new phase formation occurring during deformation, while the β-Mg17Al12 phase was entirely dissolved in the matrix. Post die forging, the mechanical properties of the AZ61+xRE magnesium alloy showed significant enhancement, with the AEZ641 alloy exhibiting the highest increases in tensile strength and yield strength, at 8.5 and 26.2%, respectively. Nonetheless, the elongation of all four alloys decreased markedly, by 42 to 52%, and hardness increased by 3.5 to 7.1%. As RE content rose, the yield strength, tensile strength, elongation, and hardness of the as-forged AEZ611 alloy reached values of 220 MPa, 302.3 MPa, 11.25%, and 65.8 HRE, respectively, showcasing the best overall mechanical properties at room temperature. During the transition from extrusion to die forging, the macrofracture exhibited distinct necking, while the microfracture revealed numerous pits, with a significant presence of second phase or RE particles located at the pits' bottoms. The fracture mechanism was identified as a mixed fracture with characteristics of toughness. [ABSTRACT FROM AUTHOR]

This article presents researches conducted on samples obtained by micro alloying aluminum alloys with germanium oxide. Experiments were carried out on aluminum-magnesium, aluminum-copper and aluminum-manganese aluminum alloys, and the hardness and microstructure of the samples obtained by casting were studied. The samples were melted in the open air in a resistance furnace and poured into sand-clay molds. Germanium oxide was added to the charge in a rolled state using a special aluminum coating. Depending on the weight of the charge and the oxide's germanium concentration, between 0.1 and 0.3 percent of germanium oxide was added to aluminum alloys. An optical metallographic microscope was used for microscopic analysis of cast samples. Studies have shown that the germanium addition significantly destroys the microstructure of an aluminum alloy with intermetallic granules. Moreover, the hardness of the researched samples was studied. The authors outlined their recommendations and conclusions at the end of the article. [ABSTRACT FROM AUTHOR]

This study explores the microstructural characterization of pearlite phase transformation in high-strength low-alloy API X60 steel, which is used in pipelines. Understanding the formation, phase percentages, and morphology of the pearlitic phase is crucial since it affects the mechanical properties of the considered steel. In this research, a phase-field model, particularly the Cahn-Hilliard approach, was used in order to simulate the formation and morphology of the pearlite phase in response to different heat treatments. Both double- and triple-well potentials were considered for comprehensively studying pearlite's morphology in the simulations. The simulation results were then compared with experimental outcomes obtained by metallography and field-emission scanning electron microscopy analyses. Considering the doublewell potential can help simulate only two phases, ferrite and cementite, which is less compatible with the experiment results than the triple-well potential, which gives the possibility of simulating a three-phase microstructure, ferrite, cementite, and austenite, and a better match with experimental data. The study revealed that as the cooling rate increases, the interlamellar spacing and layer thickness decrease. Additionally, the difference between experimental and simulation results using triple-well potential was approximately ~10%. Therefore, triple-well potential formulation predictions have better agreements with experimental results for the development circumstance of pearlitic structures. [ABSTRACT FROM AUTHOR]

The works in the field of radiation materials science of target materials of neutron sources based on the subcritical assemblies controlled by linear accelerators of electrons or protons, so-called accelerator driven systems (ADS), are reviewed. Now, electronuclear ADS systems are the prototype of safe nuclear reactors of the 5th generation. In connection with the physical start-up of the neutron source facility of the National Scientific Centre 'Kharkiv Institute of Physics and Technology' of the N.A.S. of Ukraine (NSC 'KhIPT' NASU), the target of which is fabricated from powdered tungsten covered with tantalum, the issues of preparation technology, construction, and physical and mechanical properties of W-Ta materials of targets in non-irradiated and irradiated states are considered. The nuclear-physical processes of radiation damage to the target during co-irradiation of it with both neutrons of a subcritical assembly and high-energy e- and g-beams are analyzed. The target resources of ADS systems are estimated. As noted, the difficulty of predicting the 'survivability' of the W-Ta target also relates to the fact that, except for the works carried out at the NSC 'KhIPT' NASU in 70-90th of the last century, there are no experimental works in the world on the radiation damage of reactor materials by high-energy electrons with an energy of 100 MeV and above. [ABSTRACT FROM AUTHOR]

The microstructure and phase composition of Ti–6Al–4V alloy specimens produced by wire electron-beam additive manufacturing (EBAM) technology and selective laser melting (SLM) method after exposure to an electron beam, simulating electron-beam welding, have been investigated by X-ray diffraction analysis, optical metallography, and transmission electron microscopy. In the electron beam exposure zone of SLM specimens, in contrast to EBAM specimens, it was observed that the transverse dimensions of anisotropic primary β grains and α/α′ phase plates increased and inside α/α′ phase plates, submicrocrystalline α phase grains and nanocrystalline α′′ phase were formed. The different character of microstructure and, accordingly, microhardness changes in the weld zone and heat-affected zone in comparison with the base metal is caused by the different cooling rate of the melt bath in the weld zones of EBAM and SLM specimens. In the SLM specimen, the cooling rate of the melt bath is less than that observed in the EBAM specimen. This discrepancy can be attributed to the fact that due to the finer needle-like α′ martensitic structure, the thermal conductivity in the base metal of the SLM sample is less than that in the base metal of the EBAM sample. [ABSTRACT FROM AUTHOR]

Finds of early medieval Schlingen-type swords are mostly concentrated in present-day southern Germany, where they are known from a number of graves dating to the end of the late Merovingian period. On the contrary, these swords are completely absent in contexts of the early Carolingian and Great Moravian periods. This paper presents a new find of Schlingen-type sword from Vlčí Pole in the northeastern part of Central Bohemia and its archaeometric analysis. We consider the sword from Vlčí Pole to be the only unambiguous find of a fully preserved long-bladed weapon of the late 7th to 8th century in Bohemia. As it is one of the few late Merovingian swords to have been examined using X-ray computed tomography and metallography, it also contributes to a general understanding of phenomena such as the development of the use of pattern-welded marks and blades with cutting edges of hardened steel.

The upcoming energy transition requires not only renewable energy sources but also novel electricity storage systems such as batteries. Despite Li-ion batteries being the main storage systems, other batteries have been proposed to fulfil the requirements on safety, costs, and resource availability. Moving away from lithium, materials such as sodium, magnesium, zinc, and calcium are being considered. Water-based electrolytes are known for their improved safety, environmentally friendliness, and affordability. The key, however, is how to utilize the negative metal electrode, as using water-based electrolytes with these metals becomes an issue with respect to oxidation and/or dendrite formation. This work studied magnesium, where we aimed to determine if it can be electrochemically deposited in aqueous solutions with alginate-based additives to protect the magnesium. In order to do so, atomic force microscopy was used to research the morphological structure of magnesium deposition at the local scale by using a probe—the tip of a cantilever—as the active electrode, during charging and discharging. The second goal of using the AFM probe technology for magnesium deposition and stripping was an extension of our previous study in which we investigated, for lithium, whether it is possible to measure ion current and perform nonfaradaic impedance measurements at the local scale. The work presented here shows that this is possible in a relatively simple way because, with magnesium, no dendrite formation occurs, which hinders the stripping process. [ABSTRACT FROM AUTHOR]

Hastinapur is one of the prominent painted grey ware archaeological sites in the Ganga Valley. In the present communication, we report the results of the metallurgical analysis of the excavated slag samples from the site. The existence of a large number of iron objects for this site can be dated between c. 6th century BCE and c. 16th century CE, with early iron from the 8th century BCE. The morphological, microstructural and elemental studies of the excavated slag indicate a high amount of carbon in iron, indicating crucible carburization activities at this site. In addition, the presence of niobium, cobalt, etc. in the slag indicates the usage of non-traditional iron ores in the primary ironmaking stage. [ABSTRACT FROM AUTHOR]

An in-depth understanding of the fracture behavior and mechanism of metallic shells under internal explosive loading can help develop material designs for warheads and regulate the quantity and mass distribution of the fragments formed. This study investigated the fragmentation performance of a new high-carbon silicon-manganese (HCSiMn) steel cylindrical shell through fragment recovery experiments. Compared with the conventional 45Cr steel shell, the number of small mass fragments produced by the HCSiMn steel shell was significantly increased with a scale parameter of 0.57 g fitted by the Weibull distribution model. The fragmentation process of the HCSiMn shell exhibited more brittle tensile fracture characteristics, with the microcrack damage zone on the outer surface being the direct cause of its high fragmentation. On the one hand, the doping of alloy elements resulted in grain refinement by forming metallographic structure of tempered sorbite, so that microscopic intergranular fracture reduces the characteristic mass of the fragments; on the other hand, the distribution of alloy carbides can exert a "pinning" effect on the substrate grains, causing more initial cracks to form and propagate along the brittle carbides, further improving the shell fragmentation. Although the killing power radius for light armored vehicles was slightly reduced by about 6%, the dense killing radius of HCSiMn steel projectile against personnel can be significantly increased by about 26% based on theoretical assessment. These results provided an experimental basis for high fragmentation warhead design, and to some extent, revealed the correlation mechanism between metallographic structure and shell fragmentation. [ABSTRACT FROM AUTHOR]

This study presents a microstructural investigation of the printing parameters of an AlSi7Mg0.6 alloy produced by powder bed fusion (PBF) using laser beam melting (LB/M) technology. The investigation focused on the effects of laser power, exposure velocity, and hatching distance on the microhardness, porosity, and microstructure of the produced alloy. The microstructure was characterized in the plane of printing on a confocal microscope. The results showed that the printing parameters significantly affected the microstructure, whereas the energy density had a major effect. Decreasing the laser power and decreasing the hatching distance resulted in increased porosity and the increased participation of non-melted particles. A mathematical model was created to determine the porosity of a 3D-printed material based on three printing parameters. Microhardness was not affected by the printing parameters. The statistical model created based on the porosity investigation allowed for the illustration of the technological window and showed certain ranges of parameter values at which the porosity of the produced samples was at a possible low level. [ABSTRACT FROM AUTHOR]

The foundation of materials science and engineering is the establishment of process–microstructure–property links, which in turn form the basis for materials and process development and optimization. At the heart of this is the characterization and quantification of the material's microstructure. To date, microstructure quantification has traditionally involved a human deciding what to measure and included labor-intensive manual evaluation. Recent advancements in artificial intelligence (AI) and machine learning (ML) offer exciting new approaches to microstructural quantification, especially classification and semantic segmentation. This promises many benefits, most notably objective, reproducible, and automated analysis, but also quantification of complex microstructures that has not been possible with prior approaches. This review provides an overview of ML applications for microstructure analysis, using complex steel microstructures as examples. Special emphasis is placed on the quantity, quality, and variance of training data, as well as where the ground truth needed for ML comes from, which is usually not sufficiently discussed in the literature. In this context, correlative microscopy plays a key role, as it enables a comprehensive and scale-bridging characterization of complex microstructures, which is necessary to provide an objective and well-founded ground truth and ultimately to implement ML-based approaches. [ABSTRACT FROM AUTHOR]

2219-T87 is a precipitation hardenable aluminum-copper alloy which sees wide use in structural aerospace components. Thick panels of this alloy are joined via self-reacting friction welding (SRFSW); however, this thermomechanical process can result in significant loss of the alloy's strengthening precipitates and large residual stresses which are detrimental to mechanical behavior and performance. High-resolution maps of the residual strain and stress states along the normal, transverse, and longitudinal directions of 2219-T87 SRFSW were obtained using neutron diffraction measurements. Residual stress had the highest tensile value in the heat-affected zone (HAZ) and the largest compressive stress in the base metal region of the normal and transverse directions. Line profile residual stress distributions displayed an "M"-shaped distribution in each direction with the longitudinal direction being the most pronounced while 2D residual stresses displayed an hourglass-shaped pattern. Average maximal longitudinal residual stress values ranged from 60.6 to 85.6% of yield. Microhardness testing across the transverse weld section produced a "V"-shaped curve with slight hardness recovery in the stir zone. Maximal and minimal microhardness values were observed in the base metal (154 HV) and thermomechanically affected zone (82 HV), respectively. Microstructural evolution was recorded using optical microscopy and showed decreasing grain size from the HAZ to the stir zone. [ABSTRACT FROM AUTHOR]

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An experimental metallographic method for determining strain distribution in a cold formed workpiece is presented in this paper. The method, based on the dependence of recrystallized grain size on prior deformation, was applied to a bulk formed element made of low carbon steel. Strain distribution was obtained by the calibration curve which gives the relation between recrystallized grain size and prior deformation. To determine strain values, the average grain size was measured in the longitudinal cross-section of the formed element. To accurately differentiate deformation zones, additional observation of carbides and nonmetallic inclusions morphology was utilized, also. The grain size and strain noticeably differ through the cross-section. It is observed that in the middle part, material flows freely through the die opening without significant deformation. From this zone, strain increases gradually, reaching the highest value at the contact surface of the die slope, while the top part flows radially having intermediate values of strain.

Cast (real) damascus steel (so-called “wootz”) is an ancient tool/weapon material. Due to relatively high carbon amounts, the wootz is hard to forge (or other hot-forming shaping). In some cases, the forging of wootz is impossible. During forging, cracks are often created that lead to absolutely disintegration of bulk material. In this paper is given one relationship between wootz microstructure and the forging impossibility.

This publication presents the chemical compositions of carbon reducers used in the production of ferroalloys, with particular emphasis on the content of Al, Ca, Mg, Mn, Cr, Ti, P, or S in their mineral substances. A certain amount of these elements is transferred to the produced alloys, creating inclusions and precipitations in the metal structure. Most of them are undesirable and adversely affect the final effect of the production process. The work includes sample images of the microstructure of alloys, the chemical compositions of the samples at the test point, and diffragrams. On the basis of the obtained metallographic data, technological observations are made, especially of the crushing process and the amount of grain fractions obtained. [ABSTRACT FROM AUTHOR]

The purpose of this study is to use statistical methods, namely active experimental regression analysis, to forecast the size of the intergranular sintering bridge by mathematically modeling the sintering process as it is applied to the CuSn12 alloy powder. A first-order linear design method was used to characterize the correlation between the intergranular sintering bridge and the sintering parameters (temperature and sintering time). Using the free casting of the powder into graphite shapes, nine experiments were scheduled. Following sintering, the intergranular sintering bridge was evaluated metallographically using image analysis software. In order to optimize the sintering process, a regression equation has been established by mathematical modeling that predicts the size of the intergranular bridge with sintering parameters (temperature and time) with a high probability (>95%), within the experimental limits. [ABSTRACT FROM AUTHOR]

In this study, a decorative electric heater was manufactured to reduce carbon emissions related to residential and office heating, and this heater was metallographically evaluated. In addition, the heating performance of the manufactured plate was investigated by examining its heat transfer capacity by natural convection. For this purpose, the surface of the tempered glass plate was coated with graphene by spraying to improve its electrical and heat conduction properties. Copper strips were attached to both sides of the plate to allow for an electric current. The plate was connected to mains electricity, and its change in surface temperature over time was measured. Using the measured temperature values, the heat transfer rate by natural convection on the plate surface was calculated. As a result of the calculations, it was determined that the graphene-coated tempered glass plate reached a heating performance of 40 watts after 2400 s of electrical energy supply. This value can be increased by increasing the heat transfer surface area. This study, taking advantage of the excellent thermophysical properties of graphene, will contribute to other studies conducted in this field. [ABSTRACT FROM AUTHOR]

The fire at Notre-Dame de Paris led to the discovery of several series of previously unknown iron armatures, which were systematically recorded. Amongst them, several iron staples from the top of the eaves walls, lead crest reinforcements and a sample of the tie rods used in the choir in the 19th century were analysed by metallography and tensile tests in order to determine their nature and mechanical characteristics. These results can be put into perspective with previous studies on such monuments. The chemical analysis with SEM-EDS of the slag inclusions contained in the matrix of these ferrous alloys makes it possible to determine the technical processes used for their production throughout the construction and restoration of the building, highlighting several differences depending on the typologies of the iron armatures. This information is complemented by a series of radiocarbon dates currently being carried out to better understand the periods of use of these ferrous reinforcements. When compared with those of other materials, these dates could be used to recalibrate the phasing of the building. [ABSTRACT FROM AUTHOR]

This article used Mn-Mo-Cr-B low-carbon bainitic steel as the experimental material. The continuous cooling transformation curve of the steel during continuous cooling was determined using a Gleeble-1500D thermal simulation test machine, and a corresponding phase transformation model for bainitic steel during continuous cooling was established. The influence of different cooling rates and final cooling temperatures on the microstructure and mechanical properties of the steel was investigated. Employing metallography, SEM, and EBSD techniques, the microstructure, crystallographic orientation, and grain boundary angle distribution of the low-carbon bainitic steel were explored, and their relationship with the steel's strength and toughness was studied. The research findings reveal that varying cooling rates and final cooling temperatures impact the phase transformation process and microstructure of the steel, consequently affecting its mechanical properties indirectly. With increasing cooling rate, the diffusion and fineness of martensite increase, and the quantity of lath bainite grows while the laths become finer. Elevated final cooling temperatures lead to larger martensiticaustenitic (MA) islands and reduced lath bainite quantity, causing the laths to become wider. Through analysis of the substructure of bainitic steel, it was determined that the bainite organization in the tested steel comprises primary austenite grains, lath packet, and lath block in succession. Lath packets are composed of lath blocks with different orientations, where lath size predominantly controls strength. Finer lath size corresponds to higher strength, and the influence of substructure on toughness is comparatively minor. [ABSTRACT FROM AUTHOR]

In this article, mechanical performance testing of 45# carbon steel samples with Ni/Co alloy plasma cladding was conducted through a combination of experiments and numerical simulations. The thickness of the coating of the Ni and Co base has two types of working conditions: 1mm and 0.5mm thick. The differences of the mechanical properties under different cladding thickness of the samples were experimental tested by metallographic analysis, hardness testing, abrasion resistance testing and impact resistance, by which the samples preparation has been confirmed to be essentially qualified. Then, in order to examine the improvement effect of plasma cladding technology on the sand shovel mechanical properties, the two materials were used to simulate the sand collection process of straight blade and bent blade. By analyzing mechanical representation such as stress, strain and fatigue damage, it is found that with the cladding thickness and the shovel shape difference, the force performance of the shovel is relatively different. Therefore, these factors should be comprehensively considered when selecting an appropriate cladding thickness and shovel curve to enhance the performance of the sand shovel during the sand collection process. [ABSTRACT FROM AUTHOR]

The early medieval sword from Košice-Krásna is one of the most well-preserved examples of weaponry from the region of modernday Slovakia. Discovered in 1971 during dredging activities along the river Hornád, this sword has been the subject of several studies, yet lacked comprehensive material-technological analysis until now. The sword, attributed to Petersen's type T2, features intricate inlay decoration and high-quality blade, indicating its high craftsmanship. This study revisits the sword's archaeological context, provides a detailed metallographic analysis, and explores its typological and chronological features. The findings suggest that the sword was constructed using advanced blacksmithing techniques, involving a complex assembly of different steel types to optimize its functional properties. Additionally, the contextual analysis implies that the sword's deposition in the river may reflect ritual practices rather than merely accidental loss. This research contributes to the broader understanding of early medieval metallurgy and the cultural significance of weapon depositions in riverine environments. [ABSTRACT FROM AUTHOR]

Multiple GH4169 samples were prepared with the regulation of the forming process of selective laser melting(SLM), particularly in laser power and scanning speed. The microstructure including defect morphology and distribution was observed by using metallography. The sample porosity was acquired using X-ray computed tomography(XCT), and the three-dimensional characteristics of defect were also statistically studied. The correlation of forming process and defect characteristics was finally analyzed. The results show that when the optimized energy input density is 59.1 J/mm3, the forming samples share common features of overlapping melting trace with a tidy morphology, randomly distributed pores with sizes of less than 30 -m and the density is as high as 99.9998%. Within a narrow window of forming process(220-300 W, 700-1300 mm/s), the scanning speed takes more responsibility for the sample density, and its high value tends to form extremely irregular lack of fusions(LOFs) that distribute in the overlap of melting trace. As deviating from the optimized process, the number of defects has increased, and some defect sizes are also greater than 30 ^m. The shapes of pores and LOFs respectively formed by high laser power or high scanning speed are closely related to their own sizes, that is, the larger the size, the more irregular the shape, which produces more detrimental effects than regular pores. [ABSTRACT FROM AUTHOR]

Automated Ytterbium (Yb) single pass fiber laser beam welding of High Strength Low Alloy (HSLA) steel is an expensive process, so it's a need for machining process for butt joint preparation (CNC Milling and Grinding Machining) to make it less expensive to get the same material strength after constant varying joint gap. This study aims to optimize input parameters (fixed (Power and Speed), variable (Butt Joint Gap, and Focal Length)) with respect to output parameters (Distortion, Ultimate Tensile Strength (UTS), Residual Stresses (RS)) for a 4.5 mm thick 30CrMnSiA steel. Experiments and statistical modelling (using Design of Experiment) has been performed on 0-0.5 mm butt joint gap with 0.1 mm incremental size and without filler wire. The results showed that less percentage error in distortion, UTS and RS, which are 8.19 %, 2.38 % and 6.08 % respectively. In addition, 0.2-0.4 mm joint gaps show better tensile properties and almost equal to 95 % of base material (BM), by failure appearing on the BM (aside weld) due to annealed material condition. Micro-hardness measured at the fusion zone (max. 617 HV) was almost 3 times that of the base metal (max. 208 HV). Metallography study shows that fusion zone is consisted of martensite structure due to high cooling rate during laser beam welding process, so it has more strength as compared to other two zones (Heat affected zone (HAZ) and base material). Moreover, fractured tensile sample fractography study shows the ductile behavior of failure due to presence of dimples and voids. [ABSTRACT FROM AUTHOR]

Magnesium matrix composites were developed as a form of material selection that can save fuel use due to excess magnesium, which has very low specific gravity and still has good mechanical properties. In this study, a magnesium matrix composite with nano-Al2O3 reinforcement was successfully fabricated using the stir casting method. When compared with magnesium monolithic, the addition of nano-Al2O3 particles of 0.05, 0.10, 0.15, 0.20, and 0.25 %Vf in magnesium composite casting was investigated to improve the mechanical properties of Mg/nano-Al2O3 composites. Magnesium composites with 0.20% Vf reinforcement were found to be the best composition of impact price, wear rate, density, and porosity. This is because the more reinforcement given, the more mechanical properties increase, but the agglomeration tendency of nano-Al2O3 particles is higher so that at a composition of 0.25 %Vf, there is a mechanism anomaly because the reinforcement carried out is less homogeneous. In addition to the number of amplifiers, the improvement of mechanical properties is influenced by the fabrication process, i.e. stir casting. This study uses chemical characterization of OES, EDS, and XRD, hard damage, impact, wear, density and porosity testing, and metallographic observations using OM and SEM. [ABSTRACT FROM AUTHOR]

An experimental metallographic method for determining strain distribution in a cold formed workpiece is presented in this paper. The method, based on the dependence of recrystallized grain size on prior deformation, was applied to a bulk formed element made of low carbon steel. Strain distribution was obtained by the calibration curve which gives the relation between recrystallized grain size and prior deformation. To determine strain values, the average grain size was measured in the longitudinal cross-section of the formed element. To accurately differentiate deformation zones, additional observation of carbides and nonmetallic inclusions morphology was utilized, also. The grain size and strain noticeably differ through the cross-section. It is observed that in the middle part, material flows freely through the die opening without significant deformation. From this zone, strain increases gradually, reaching the highest value at the contact surface of the die slope, while the top part flows radially having intermediate values of strain. [ABSTRACT FROM AUTHOR]

Vértesszőlős was a populated area during the broad period of the Bronze Age. Artefacts from different cultures, and among them many bronze objects were found. Most are ornaments, but tools and weapons have also been unearthed. Jewellery and dress ornaments are found in many areas, and the examination provides an opportunity to compare regions, ages, and customs. Several stud ornaments and sporadic stud fragments were found during the excavation. Making studs requires careful elaboration and production. In general, it was stated that they were made of an alloy with a low and average tin content (3.5 -6 w% tin), which is malleable and easy to deform plastically. The morphology of the inclusions also suggests a high degree of plastic deformation. Due to the thin bronze material, the objects are subjected to solid corrosion effects, necessitating a detailed microstructural examination to examine the other constituents. The spiral beads require similarly careful elaboration, two of which were selected for parallel examination. A similar test protocol had to be used to determine the effect of corrosion. A slightly higher tin content and a more minor total deformation were found. The objects are also compared for inclusions and other impurities.

In Roman times, according to sources, mining and metallurgy were organized and managed centrally. The area of Pannonia was supplied with iron ore from the Majdan Mountains from the early Iron Age onward, which was then largely processed according to needs by local blacksmiths. Particularly interesting questions are raised by the square column bars found at several sites in Southern Transdanubia. Similar finds were found in 1880 near Hrvatska Dubica in Croatia. Aleksandar Durman hypothesized Syrian influences in the production of iron bars, defined as Roman and about 20 cm long, forged to a weight of 11–15 libra, or 3.6–4.91 kg, based on finds found in the vicinity of the aforementioned site. In Pannonia, square column-shaped iron bars are known near the Danube (Intercisa – Dunaújváros) and the Kapos Valley (Dombóvár, Regöly), but they are heavier than the finds from Croatia, weighing 5.4–10 kg. Iron metallurgy is highly technology- and raw material-dependent, and is traditional in every detail, even from compulsion to ensure quality. Therefore, metallographic examinations play a particularly important role in research. A recent analysis of Pannonian square-bar bars shows that several pieces of bloom were forged during their production. Their microstructure is heterogeneous, typically ferrite-perlitic in which ferrite is found with Widmanstätten morphology. All indications are that the raw material blocks provided a standard good quality raw material for the production of different tools, weapons, etc.

Abstract Excavations at the Chalcolithic site Fazael in the central Jordan Valley uncovered a large number of metal items, many of them polymetallic copper alloys cast in the lost wax technique. Metallography and SEM–EDS analysis on a subset of the assemblage confirm previous notions of the lost wax metallurgy in the Chalcolithic Southern Levant but extend them significantly in three aspects: The Fazael metal assemblage is slightly depleted in its arsenic content compared to metal assemblages from other sites, silt-sized quartz inclusions in unalloyed and polymetallic copper items, and the presence of unalloyed copper inclusions. These latter provide the earliest direct evidence for mixing of different metal types in West Asia, potentially alloying or recycling.

This article presents a comparative analysis of the crucial physical properties of electrically conductive components made of pure copper, produced by various additive manufacturing technologies such as binder jetting (BJ) and direct metal laser sintering (DMLS). The comparison concerned the assessment of critical parameters important from the application point of view, such as: electrical conductivity, hardness, yield point, microstructure and the occurrence of internal material defects. Same-sized components made in a conventional casting and subtractive method (machining) were used as a reference material. Comprehensive tests and the comparison of a wide range of parameters allowed us to determine that among the selected methods, printing using the DMLS technique allowed for obtaining arcing contact with mechanical and electrical parameters very similar to the reference element. Therefore, the obtained results showed the possibility of using the copper elements made by additive manufacturing for the switching and protection devices used in electrification and energy distribution industrial sectors.

Archaeological research at Hoeke, a Late Medieval outer harbour of Bruges (Belgium), has revealed large quantities of iron slags, fuel and other remains of iron working. Archaeometrical study has provided an enhanced insight into the historic iron working process, a craft activity which had up till now remained completely unknown in one of the largest economic hubs of medieval Europe. Several petrological, mineralogical and geochemical analytical methods have been applied for this purpose. The metallographic analysis was performed using reflected light optical microscopy, while the mineralogical composition of the slags was characterized X-ray Diffraction (XRD) Spectrometry. Macroscopic identification of plano-convex bottom slag and hammerscales, combined with the geochemical data pointed out that the examined slag is indicating smithing activity, while no traces for iron ore melting were discovered. [ABSTRACT FROM AUTHOR]

In the present incident, one of the rollers of grinding mill in cement plant failed during operation, exhibiting longitudinal cracking over inner surface. Deposition welding was carried out just before the incident to match the worn-out profile of the roller. Investigation revealed that the subsurface of the cracked region contained discontinuities like blow holes (≤1.0 mm) and fine cracks (0.2–2.0 mm length). Chemical analysis of the alloy showed low nickel (0.5 wt.%) and high tungsten (~1.0 wt.%) concentration. The deviation in composition reduced the ductility of the component. Microstructure of the alloy consisted of complex carbides (50–200 μm) embedded in martensite–austenite matrix. Under cyclic loading, the fatigue crack was initiated from subsurface containing discontinuities and bulky carbides. Low toughness (~2 J) and high residual tensile stress (~170 Mpa) of the material facilitated crack propagation through thickness direction. Final failure of the component occurred due to overload. [ABSTRACT FROM AUTHOR]

Friction stir welding has found wide application in aircraft and rocket engineering, primarily due to the possibility of obtaining welded joints with a strength close to the strength of the base material. One of the most promising methods of such welding is spot friction stir welding that can serve as an alternative to electric contact spot welding and rivet joints. For the introduction of spot friction stir welding into the production of critical products, it is necessary to consider issues related to nondestructive quality control of welded joints obtained by this welding method. The purpose of this work is to substantiate the applicability of the ultrasonic echo method to quality control of welded joints obtained by spot friction stir welding. The relevance of the work is confirmed by the fact that to date there is no sufficiently complete information about the results of experimental studies aimed at analyzing the characteristics of welded joints obtained by spot friction stir welding. The authors of the article propose to use the ultrasonic echo method. The testing was carried out using an ultrasonic flaw detector with a dual-element piezoelectric transducer on samples prepared using spot friction stir welding. As a result of ultrasonic testing, defects such as lack of penetration and sloting were found in three samples; this was confirmed by metallographic studies. Samples with no defects were subjected to mechanical tests, as a result of which it was found that the strength of the resulting welded joints is comparable to the strength of the base metal in the samples. Metallographic studies carried out on the samples after mechanical tests also confirmed the lack of defects in the welded joints. Thus, we show the relationship between the results of ultrasonic testing, metallographic studies, and mechanical tests, which allows us to substantiate the applicability of the ultrasonic echo method to quality control of welded joints obtained by spot friction stir welding. [ABSTRACT FROM AUTHOR]

Although the recycling of materials such as copper and glass is widely known and generally well understood within archaeological contexts, far less is known about the recycling of iron. Iron recycling is more complex than that of other metals for two reasons. First, normal manufacturing processes, which include forging several components to make a composite object, offer the opportunity to include recycled iron. Second, the material itself is more complex than Cu alloys. The alloys of Fe, depending primarily on C content, are very different in terms of properties and can be interconverted by (normally) removing C such as decarburizing cast iron to make wrought iron. Thus, recycling practices are potentially intimately combined with such processes. These factors, combined with the poor preservation of archaeological iron and the consequent reluctance to carry out extensive studies (which often require destructive analysis via metallography), mean that there are no clear criteria for identifying recycled iron. However, limited historical documentation suggests, at least indirectly, that such recycling was common. This paper is neither comprehensive nor definitive, but merely intends to promote discussion and awareness of iron recycling by hypothesizing several possible mechanisms and providing a few illustrative archaeological examples. [ABSTRACT FROM AUTHOR]

The microstructure and tribological properties of the modified surface of 12Kh2N4A (its equivalent is E3310) and 38Kh2MYuA (its equivalent is A290C1M) structural alloy steels after laser treatment (LT) are studied using an ytterbium continuous-wave fiber laser. The laser surface treatment is carried out in air at a laser power of 75 and 100 W and a laser beam scanning velocity varying in the range of 2 to 14 mm/s. The micro- and macrostructures of the steels are examined using metallography and durometry; the structure of the laser-affected areas (LAZ) and steel constituents are determined. The scanning velocity at a laser power of 100 W is shown to have the most significant effect on the LAZ dimensions. The maximum depth of the LAZ during LT without surface melting in the studied modes is 310 μm for 12Kh2N4A steel and 170 μm for 38Kh2MYuA steel. According to the hardening mode, the microhardness in the LAZ increases from 1.36 to 1.97 times for 12Kh2N4A steel and by 2.0–2.6 times for 38Kh2MYuA steel. The tribotests performed using a pin-on-disk configuration show that the reduction of linear wear and wear rate in the 12Kh2N4A and 38Kh2MYuA steels at a hardened layer depth of ~100 μm is 26.6 and 43.9%, respectively. [ABSTRACT FROM AUTHOR]