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Severe abrasive wear of drill pipe and casing often occurs in exploration drilling operations. To achieve the surface enhancement of the drilling components in terms of abrasive wear resistance, various flux-cored wires (FCWs) containing multiple alloying elements were developed, and the Fe-based hardfacing layers were developed by metal active-gas (MAG) welding process. The macro morphology, microstructure, and phase composition of the alloys were characterized by using OM, SEM, XRD, and EDS methods, while the wear resistance performance was measured by using an abrasion tester. The results showed that the hardfacing layer prepared by Fe-Cr-C FCW is hypoeutectic that mainly consisted of austenite matrix and (Fe,Cr)7C3-type carbides. On this basis, a higher C content in combination with Nb, Ti, and B additives resulted in the microstructure comprised of martensite-based matrix and the precipitations of (Nb,Ti)C and Fe2B hard phases. With the removal of Cr, the further addition of Nb, Ti, and B, the hard phases change from particles to bulk and lath shapes. The hard phases with higher microhardness values than the matrix contributed to an improved Rockwell hardness and a highly decreased wear weight loss of hardfacing layer. Accordingly, the wear mechanism changed from severe plastic fracture to micro-cutting going with a slight brittle micro-peeling. The interlaced distribution of (Nb,Ti)C and Fe2B provided a stable skeleton that enables an further enhanced abrasive wear resistance.

The effect of the axial static magnetic field (ASMF) on cleanliness and microstructure in magnetically controlled electroslag remelted GCr15 bearing steel ingots was investigated experimentally. The results show that a magnetically controlled spin-vibration induced by the interaction of the ASMFs and the remelting current exists at the consumable electrode tip, resulting in thinner liquid melt film and smaller droplets. With the increase in magnetic flux density, the optimization effect of ASMFs on electroslag remelting process increases and reaches the peak with a 40 mT ASMF, then decreases. The cleanliness of the ingots was improved, and the count of inclusions larger than 5 μm was reduced. The microstructure of the ingots processed with a 40 mT ASMF was significantly refined. The depth of the metallic molten pool was reduced from 45.2 to 17.5 mm with the application of 40 mT ASMF. The tensile strength, impact toughness, and Rockwell hardness of the ingots obtained under the 40 mT ASMF were significantly improved. The mechanisms of the spin-vibration occurring at the electrode tip end were interpreted in detail to elucidate the effect of ASMFs.

The present study evaluates the process activation energy or thermal diffusion activation energy (TDAE) to understand the aging kinetics or transformation kinetics. AA7075–5 Vol.% of SiCp composite were fabricated through stir casting technique. Differential scanning calorimetry (DSC) was carried out at different heating rates to understand the precipitation sequence and evaluate the process activation energy or thermal diffusion activation energy (TDAE) of composite. Rockwell hardness tests investigated the aging behavior of AA7075–5 Vol.% of SiCp composite. Results show incorporation of SiCp in the matrix does not affect the sequences of formation and dissolution of precipitate but affects the kinetics of precipitation growth. The formation of precipitation in the alloy and composite requires an access amount of vacancies; an increase in dislocation density may result in heterogeneous nucleation of precipitation and create free path for the kinetically faster atomic transportation of precipitates. Hence, incorporation of SiC particles in the composite would offer a lot of nucleation sites for precipitate, resulting in lower activation energy to form precipitates and takes less time to reach the maximum hardness. In contrast, the addition of a lesser volume fraction of SiCp also showing accelerated aging phenomena in the composite during the aging process. The hardness profile shows hardness increases 3.86% compared to the base alloy AA7075. High-resolution transmission electron microscope (HRTEM) micrograph of peak age (T6) condition divulges that enormous fine and plate-like ή (MgZn2) precipitates are uniformly distributed in the composite.

In order to effectively improve the environmental problems caused by steel slag stacking, the air-quenching process of molten steel slag was carried out, and the properties of the air-quenched steel slag (AQSS) has been investigated by various characterization methods. The results show that the main phases of AQSS were Ca2SiO4, RO phase (solid solution formed by MgO, FeO, and MnO) and Ca2Fe2O5. The AQSS met the technical requirements of a sandblasting abrasive. In addition, the Rockwell hardness of the AQSS with particle size of 1.0–3.0 mm exceeded 50.00 HRC. The particle size of 1–2.5 mm was particularly adapted to use as a sandblasting abrasive. It is clear that AQSS can be used as a sandblasting abrasive by analyzing and comparing the particle size and hardness of the AQSS and commonly used sandblasting abrasives.

Hand tooling represents a sizable cost in many industries, which is often exacerbated by premature tool failures. Prevention of these failures is a cost-saving strategy that can be applied to industrial as well as personal projects. The present study employs an integrated theoretical, experimental, and computational approach to investigate the failure of a socket drive adapter of unknown material after being subjected to unknown torsional loading. The failure surface was first compared against a torsion-tested chromium-vanadium adapter using scanning electron microscopy, and it was determined that a torsional overstress caused ductile shearing around the periphery of the adapter, until the smaller cross-sectional area allowed a smaller, non-torsional load to induce a final tensile failure. Results obtained from optical emission spectroscopy and Rockwell hardness test indicated that the failed adapter was likely made from AISI 1025 or a similar grade mild steel, which had been extensively cold worked and/or heat treated during the production process to improve its strength. Finite element analysis was then used to confirm the validity of theoretical calculations for maximum stress at the failure location. The approximate failure load was finally estimated via a strength-hardness correlation, with a conservative estimate for allowable torque of as little as 10.6 N m. The method presented in this paper shows that the load applied on hand tools in everyday use can be too high and can cause failure. The quality of the hand tools plays a key role in determining the amount of load that the hand tools can withstand.

The main objective of this work is the fabrication of functionally graded aluminum ceramic composite (FGACC) using centrifugal casting and to study its physical and mechanical properties. LM6 aluminum alloy and silicon nitride (Si3N4) are mixed to form FGACC. This enables the material to have the best of both materials. Si3N4 is varied in size of 30 and 3 µm and volume fraction of 8% and 12%. Centrifugal casting was carried out based on L4 orthogonal array. The gradual change in the distribution of reinforcement of the casted FGACC is ensured using optical microscope SEM and hardness. Image Analyser software was used analyze the volume fraction of phase and grain size for all FGACCs. It was observed that the Si3N4 concentration increases from the inner to the outer periphery of the casted ring. This is due to the radial forces generated from centrifugal casting to segregate a second discrete phase from the matrix of composite materials. Rockwell hardness values increased from the inner to the outer region ensuring the gradual increase in Si3N4. Hardness increased by 30 and 22% in outer for 3 and 30 µm. Archimedes principle was used to find the density based on which the porosity was calculated. Porosity values were 1.8% in the outer region and 2.97% in the inner region. SEM images were also used to characterize the FGACC. ANOVA was done to find the most influencing parameter on hardness. R2 value for the outer region was 99.24%, indicating that the developed model is accurate and fits very well with experimental values.

In this work, nanocellulose (NC) was prepared by a new route consisting of dissolution of cellulose in phosphoric acid followed by regeneration in water. To facilitate the dissolution, the cellulose was pre-treated with aqueous solution of urea. Although the regenerated cellulose from water had been in nanoscale, its size could be further reduced through ball milling. The composition, structure, and morphology of the materials from different preparation stages were studied by infrared spectroscopy (FTIR), X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. NC was then incorporated into the HDPE based wood-plastic composites (WPCs) in a skillful way to guarantee its good dispersion. The influence of addition content of NC on the mechanical and thermal properties of WPCs was investigated comprehensively. WPCs incorporated with NC exhibited an obvious increase in impact strength compared with those without NC. In addition, the Rockwell hardness, Vicat softening temperature and thermal stability of WPCs incorporated with NC were also correspondingly improved. The effect of ball milling on the size of nanocellulose was also investigated. The application results showed that the NC prepared without ball milling was more efficient in enhancing the toughness of WPCs.

In this research, the nitride titanium layer was deposited on AISI 316L stainless steel and the adhesion of the optimum layer had been evaluated. The electrophoretic deposition process was carried out with optimum composition and under the variation of diverse voltages of 20, 25, and 30 V and time of deposition of 3, 5, 7, and 10 min. Sintering at 1200°C within 2 and 4 h was applied on the achieved nitride titanium coatings to improve adhesion of the layer. The obtained layers were characterized by X-ray diffractometry and scanning electron microscopy. Results show that the sample achieved at 25 V within 5 min has uniform layer on the surface of the substrate. Adhesion strength was evaluated by performing Rockwell C hardness test according to VDI 3198 guideline on the optimum sample with uniform layer and the crack propagation was studied by using SEM. Results show that although there is a ductile feature of the layer in macroscale, it has brittle feature in microscale and acceptable adhesion strength of as-sintered sample.

In the present work, the microstructure and mechanical properties of microwave welded Al6061-6%Graphite-SiC hybrid metal matrix composites (MMC) were investigated. The microwave welding was carried out using the principle of microwave hybrid heating and Al6061 powder as an interfacial material. The domestic microwave oven having the frequency of 2.45 GHz and 900 W power was used for the experiments. The charcoal powder as a susceptor was used during the welding process. The hybrid MMCs Al6061-6%Gr-SiC were developed through stir casting process with different weight percentage of SiC keeping graphite constant. The joints were characterized using x-ray diffraction, scanning electron microscope (SEM) equipped with energy-dispersive spectrum (EDS), Rockwell hardness tester and universal testing machine. The x-ray diffraction analysis showed the presence of harder aluminum carbide and aluminum oxide phases. The microstructural study revealed the good metallurgical bonding between the interfacial composites with absence of cracks. The elemental analysis of joint revealed the presence of aluminum, carbon and oxygen with other elements. The average ultimate tensile strength of the microwave joints was recorded as 135 MPa with 4.3% elongation. The average Rockwell hardness at the weld joint observed was 61.5 ± 5 HRB. The evaluation of mechanical properties of microwave welded composites indicated the increase in the tensile strength and hardness as the content of SiC reinforcement increased. The joint strength found to be 65.15% of parent composite, which is similar to the joint strength of welded aluminum-based composites by various techniques such as friction stir welding, laser beam welding, electron beam welding, etc. The present investigation has showed that the microwave energy can be used successfully, as an alternative method to weld the composites.

The paper presents investigations of the structure, phase composition and properties of the rail running after bulk steel hardening. Investigations are performed at a different depth by using modern techniques of material physics in extremely long operation conditions (gross weight of 1411 million tons). The Rockwell hardness measurements at a depth ranging from 2 to 10 mm, show a decrease in the hardness level from 37.1 to 35.8 HRC and in the microhardness – from 1481 to 1210 MPa, respectively. The multiple modifications of the rail running surface include the disintegration of lamellar perlite and the formation of the submicron size subgrain structure varying between 100 and 150 nm; the formation of 30–55 nm carbide phase nanoparticles on the grain boundaries and in the subgrain volume; the growth in microdistortions and the crystal lattice parameter of the α-Fe solid solution; the increase in the scalar dislocation density. Possible reasons of these changes are discussed herein.

In order to elucidate the relationship between red hardness/toughness and tungsten content, strong carbide-forming element tungsten was added to a 5 wt.% Cr medium carbon steel (Cr5) in melting. After normalization and forging, the vacuum gas-quenched experimental steels were tempered at 560 and 600 °C for 10-40 h, respectively. Rockwell hardness and un-notched impact energy were evaluated. It was revealed that the precipitation phases play a critical role in the mechanical properties of the steels. The tungsten element effectively improved the red hardness of the steel by 6.3-15.8% when tempering at 600 °C for 10-40 h, while the corresponding impact toughness holds at the same level, about 250J, as Cr5 steel. Through observations by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), mesoscales carbides were found with a structure of (Fe, Cr, W, Mo, V)6C. It was deduced that tungsten element acts a positive role in inhibiting the coarseness of secondary M6C-type carbides and impeding the formation of M23C6 and M7C3, and thus enhances the thermal stability of Cr5W steel at elevated temperature. Furthermore, the tempering stability prediction model was constructed to predict the red hardness of tungsten-containing Cr5W steel.

Silver has wide-ranging applications, such as industrial equipment, semiconductors, musical instruments, and silverware. Despite its diversified applications, publications on its strain-hardening characteristics are rare. In this work, tensile and hardness tests were performed for cold-rolled specimens at different levels of thickness reduction after full annealing. Up to the true strain of 1.7, strain-hardening characteristics and variations in Rockwell hardness were obtained for 99.9% pure silver. The consistency between the true stress–strain curve and the hardness data was confirmed through finite-element modeling and analysis of the hardness test procedure. Strain-hardened pure silver was verified to have yield strength comparable to sterling silver. For applications where both of purity and deformation resistance are important, strain hardened pure silver could be a practical candidate.

Aluminum-based metal matrix composites (MMC) are very popularly used in the aircraft, automotive, and armament industries because of their high young’s modulus, specific strength, and enhanced wear properties. In this research, Al6061/SiC composites are produced using the powder metallurgy technique by varying Wt.% SiC (0, 5, 10 and 15) and sintering duration (1, 2 and 3 h). The effect of SiC Wt.% and sintering durations on the composites properties are examined using a scanning electron microscope, Rockwell hardness test, and Charpy impact test. Both Wt.%SiC and sintering duration substantially impacted Al6061/SiC composites mechanical properties. The morphological study of 15Wt.%SiC composite sintered for 3 h confirms the absence of microcracks and SiC clusters with good interfacial bonding between Al6061/SiC. It is observed that long sintering duration stimulated thermally activated diffusion-controlled grain growth, which adversely affected the mechanical properties and rendered superior characteristics that are otherwise impossible. The hardness and toughness of composite increased from 73 to 81 HRB and 3.2 J to 5.2 J, respectively, under the best process conditions.

The effects of traditional heat treatment (quenching and then tempering) and deep cryogenic treatment on the microstructure and mechanical properties of a low-carbon high-alloy martensitic bearing steel were studied by Rockwell hardness test, X-ray diffractometry, scanning electron microscopy and transmission electron microscopy. The results show that the deep cryogenic treatment promotes the transformation of the retained austenite to martensite during cooling, which leads to the hardness of the sample after deep cryogenic treatment higher than that at the quenched state. Also, the carbon content in the martensite matrix after different treatments was calculated and the results indicated that deep cryogenic treatment can promote the segregation of carbon atoms in martensite to dislocations. The segregated carbon atoms act as and grow into nuclei for the formation of fine carbide particles during subsequent tempering. And this resulted in the fact that the hardness of the tempered experimental steel after deep cryogenic treatment is higher than that without deep cryogenic treatment.

In this study, the function of rare earth (RE) oxides added in boronizing agents was studied by analyzing not only the boronized titanium (Ti6Al4V) but also the agent materials at 900–1050 °C. XRD results showed that low-melting-point RE borates were formed in the boronizing processes. The existence of the RE borates probably provided a partially liquid boronizing environment for the titanium alloys. By scaling up the boronizing process for larger samples, not only borides but also carbides were formed on the samples indicating a borocarburizing process occurring. The boronized alloys showed excellent mechanical properties (Vickers hardness 1800HV0.1, Rockwell hardness 95–98 HR15Y up to 900 °C, tensile strength 941 MPa, fiction coefficient 0.15, friction bonding strength >300 N) and a good burner rig thermal shock performance (without spallation of surface oxide).

Calcium carbonate is widely used as a filler material in the production of polymer matrix composites and studies have shown that eggshell contains about 94% calcium carbonate. The effect of calcium carbonate from eggshell particles in polypropylene was studied in this work and the result compared with unreinforced polypropylene. Industrially synthesized calcium carbonate/eggshell particles were used as filler in polypropylene matrix with varying mass fractions from 5 to 20 wt. % at 5 wt. % increment. The produced samples were mechanically characterized for indentation hardness and uniaxial tensile properties using a Rockwell hardness tester and universal mechanical testing machine respectively. These properties were measured at different compositions to determine its compositional dependence. Microstructural analysis of the composites top and fracture surface was also carried out using scanning electron microscope to examine possible failure mode. The results were compared to measure the effect of reinforcement and the replacement criteria for the conventional calcium carbonate. The results obtained showed that calcium carbonate reinforced polypropylene has its highest tensile strength, elastic modulus and modulus of rupture at 5 wt. %, ductility and modulus of resilience at 10 wt. %, and hardness at 15 wt. %. The results also showed that granulated eggshell can provided appreciable improvement in the mechanical properties of polypropylene as obtainable in mineral calcium carbonate reinforced polypropylene.

Limited availability of natural or monolithic materials all over the globe faced huge challenges for superior quality material. In this context, the hybrid composite exhibits tremendous metallurgical, physical, mechanical, and tribological properties and also in the favor of economical and eco-friendly conditions which are declared as the boon for various manufacturing and constructional sectors. This paper deals with an innovative and latest classification of hybrid composites, widely used processing routes, the examination of different material properties, modes of the testing method, and modern optimization techniques. In the present article, a novel comparative analysis for the fabrication of HYBRIDMMCs through which various advanced organic and inorganic reinforcements and base materials with associated fabrication challenges and remedial outcomes are thoroughly discussed. Based on the rigorous literature review, stir-squeeze casting followed by powder metallurgy and infiltration technique is highly recommended for the better enhancement of surface morphology, density, porosity, mechanical properties (i.e. Rockwell hardness, Brinell hardness, Vickers hardness, tensile strength, and ultimate strength) and tribological properties (i.e. wear loss and coefficient of friction) of hybrid metal matrix composites.

The effect of austenitizing temperature on microstructure evolution and impact toughness of a newly developed Fe–3.0C–2.8Si–2.0Mn–0.9V–0.2Cr bainite ductile iron was investigated in this research. The ductile iron specimens were heat treated under different continuous cooling process, involving austenitizing between 900 and 980 °C and followed tempering at 200 °C. Optical microscopy, X-ray diffraction, scanning electron microscope and transmission electron microscope tests were conducted to investigate the microstructure evolution. Impact toughness and Rockwell hardness were measured. The results showed that the microstructure of the ductile iron mainly consisted of graphite, acicular bainite and retained austenite after continuous cooling process. The austenitizing temperature could change the volume fraction and size of bainite and retained austenite. There existed a C-area, where retained austenite accumulated near the graphite, except for specimen austenitized at 920 °C. The impact toughness of specimens increased first and then get worse with the increasing of austenitizing temperature. The impact toughness was related with the volume fraction of bainite and the morphology of retained austenite. The fracture mechanism of the bainite ductile iron belonged to cleavage fracture. Chunky graphite acted as the source of microcrack during the impact process. The bulky retained austenite behaved as a prior path for the microcrack propagation, while the bainite and thin filmy retained austenite limited its propagation.

Cold rollings of A1008 steel specimens are carried out in this study to analyze the influences of roll’s surface pattern and specimen’s reduction ratio on surface morphologies, optical properties, and mechanical properties of rolled samples. A 3D fractal formula, along with dedicated algorithms developed, is applied to solve the periodic (characteristics) lengths and fractal dimensions for roll and rolled surfaces along and perpendicular to the rolling directions. The correlation for every fractal parameter between roll and the rolled specimen is developed to be a function of roll’s surface pattern and reduction ratio first. The light tracking simulations were then carried out for rolled samples only. Rockwell hardness and tensile tests were conducted to evaluate the specimen’s hardness and Young’s modulus. A roll having a higher fractal dimension, or a longer periodic length, can result in a higher fractal dimension and a longer periodic length of the rolled specimen, respectively. A larger reduction ratio also results in the rolled surface with higher fractal dimensions and longer periodic lengths. Increasing the fractal dimensions of a rolled specimen can elevate the maximum illuminance and, conversely, lower the minimum illuminance, while an increase in periodic lengths can increase the minimum illuminance and decrease the maximum illuminance. A decrease in the fractal dimensions and/or increase in the periodic lengths of rolled surfaces in the two directions can raise the illuminance uniformity. For the specimens prepared with the same roll pattern, an increase in reduction ratio can bring an increment in illuminance uniformity and hardness of rolled samples. This study provides an efficient way to determine the roll pattern and reduction ratio that satisfies the specific demands in optical properties.

An attempt was made to synthesis ex-situ formed Al/SiC MMC and in-situ formed Al/TiB2 MMC using stir casting method with different weight percentage of the ceramic particulates such as 4 wt%, 6 wt% and 8 wt% respectively. Significant improvements of mechanical properties were observed when the addition of reinforcement particulates increased from 2 to 8 wt%. The tensile strength and Rockwell hardness of the ex-situ and in-situ formed composites were conducted as per the ASTM standard E08-16 and ASTM standard E18-15 respectively. The in-situ formed TiB2 MMC has superior mechanical properties such as 0.2% proof strength, tensile strength and hardness as compared to ex-situ SiC MMC as well as base metal. It is also concluded that the mechanical properties were increased with increase in wt% of reinforcement particles additions. The Optical Microscopy and Scanning Electron Microscopy were used to examine the size and uniformity of reinforcement particles whereas the Energy Dispersive X-ray analysis, X-ray diffractometer and Element Mapping analysis were used to confirm the presence of TiB2 particles.

The Standard Test Methods for Tension Testing of Metallic Materials (ASTM E8) mandates a specimen gauge reduction for obtaining the tensile properties of reinforcing steel bars. The standard outlines the specimen preparation requirements and methods to ensure that test results well represent the material properties. On the other hand, some codes differ regarding the approach to specimen preparation. They do not apply gauging, for both deformed and plain steel bars. Thus, the effect of specimen gauge reduction on the tensile properties of reinforcing steel bars was evaluated, and the interconnection of properties to the layer hardness was analysed. The experiment governed a range of deformed hot-rolled bar sizes, tested in tension using precision instruments. The Rockwell hardness test was implemented layerwise on the specimen’s cross section, and the hardness number (HRC) was measured as a function of the layer distance to the centre. A finite element model was constructed to study the stress concentrations induced by a constant indentation, simulating the HRCs, and to numerically construct the stress–strain relationship of ungauged steel bars based on the core properties and the section HRC relationship. Scanning electron microscopy readings were performed to visually and chemically justify the results. It was shown that the specimen gauge reduction significantly influenced the resulting stress–strain behaviour of the material, and the yield and ultimate strengths were reduced. It was also demonstrated that the hardness response is proportional to the distance to the specimen’s axes. The corresponding yield and ultimate strengths thus increased accordingly, from the inner to the outer layers of the bar. Testing a gauged specimen will therefore result in lower strength than that of an ungauged steel bar.

The pack boriding process of Fe-based powder compact was carried out at 850 to 1050°C for 3 to 10 h. The microstructure and the thickness of the boride layer were observed by VHX-6000 ultra-depth microscopic three-dimensional microscope. The surface hardness of the boride layer was measured by a Rockwell hardness tester, the phase composition of the boride layer was analyzed by X-ray diffractometer and the friction and wear properties of the sample were tested on the MMW-2 friction and wear tester. The worn surfaces of boride layer was observed by scanning electron microscope. The results show that the boride layer was mainly composed of Fe2B single phase, and its thickness was uniform and firmly bonded to the substrate. The thickness and hardness of the layer gradually increased with time and temperature. The binding force between the layer and the substrate would be decreased while the thickness of the layer was too thin or too thick. Boriding at 850, 900, and 950°C resulted with formation of Fe2B phase while FeB and Fe2B phases occurred at 1050°C. The thickness of the layer in a suitable range could improve the wear properties of the material.

The current paper investigates the mechanical behavior of Al-6063 hybrid composites reinforced with silicon carbide (SiC) and rare earth (RE) oxides. Hybrid composites containing wt% of SiC as 3, 6 and 9% and (CeO2 + La2O3) mixture as RE oxides as 1,2 and 3 wt% were fabricated using stir casting technique. The scanning electron microscopy (SEM), X-Ray diffraction (XRD), electron backscattered diffraction (EBSD) and energy dispersive spectroscopy (EDS) analysis were used to characterize the prepared samples of hybrid composites. The mechanical characterization including Rockwell hardness, Vicker’s microhardness, impact strength and tensile strength were tested as per ASM standards. The fractured samples of different hybrid composites were studied using SEM. The highest value of Rockwell hardness was observed as 69 HRB in composite sample with 6 wt% of SiC and 2 wt% of RE mixture. For the same sample, highest value of Vicker’s microhardness was found to be 114.24 HV. Furthermore, highest value of tensile strength and impact strength was observed to be 91 MPa and 56 J for the same sample. The obtained data were analyzed on Design Expert software Version 6.0.8 using two level factorial designs afterward. The regression equations obtained from the software is validated using diagnosis plots and the optimized values of reinforcements are obtained using desirability analysis.

The solidified microstructure and carbide precipitation behavior in an S390 high-speed steel processed by electron beam melting (EBM) have been fully characterized. The as-EBM microstructure consists of discontinuous network of very fine primary carbides dispersed in auto-tempered martensite matrix together with a limited amount of retained austenite. The carbide network consists of M2C/M6C and MC carbides. Both the columnar and near-equiaxed grain structures were found in as-EBM microstructure and the presence of inter-dendritic eutectic carbides assisted in revealing the dendritic solidification nature. The top-layer microstructure observation confirmed that the columnar dendritic structured grains were located adjacent to the micro-melt pool boundary, indicating an epitaxial growth with the average growth direction parallel to the maximum thermal gradient. At the center of the micro-melt pool, the near-equiaxed grains were developed by dendritic growth parallel to the beam traveling direction. The carbide decomposition was revealed by scanning transmission electron microscopy and confirmed by transmission Kikuchi diffraction. The MC carbides (rich in V followed by W) nucleated at the interface between M2C (W, Fe, Mo, and Co in the order of significance) and the matrix and then grew from the outside inward, but their nucleation might occur from the M2C carbide itself. The thermal effect induced by the adjacent scan lines seems to trigger a solid-state phase transformation of MC → M2C + γ-Fe. The elemental migration was theoretically calculated and compared with the experimental results. The high hardness of ~ 65 HRC and good transverse rupture strength of ~ 2500 MPa in as-EBM S390 means that EBM processing can be used to fabricate highly alloyed tool steels. With the help of the post-processing heat treatment, the best Rockwell hardness of 73.1±0.2 HRC and transverse rupture strength of 3012±34 MPa can be obtained.

A successful excavation of roadheaders depends on the cutting performance and the tool life of conical picks. Tool life is important in terms of wear rate which is affected by different rock parameters such as equivalent quartz content, mineral grain size, as well as cutting parameters on the cutterhead. In this study, analyses among wear rate, specific energy, advance rate, and cutter consumption were carried out. The wear mechanisms of two different models of conical picks were examined from different aspects depending on rock and machine parameters. Their relation with the mechanical and abrasivity properties of rocks and petrographic analyses were investigated. In addition, the metallurgic content and Rockwell hardness of conical picks were determined to describe the metal alloys and their effects on the wear of cutting tool. The results showed that the metallurgic content, pick positions, and other environmental conditions influence the wear mechanism. Finally, two different models were proposed to estimate the pick consumption in sandstone and siltstone rocks based on actual data obtained from coalfield.

Determination of mechanical properties in bulged specimens has its own challenges due to their nonhomogeneous geometry. In the present study, a set of empirical hardness-strength-hardening law correlations is proposed to estimate the flow behavior of the bulged specimens. To do so, comprehensive empirical strength-hardness correlations applicable for all aluminum alloys were developed by collecting datasets from 16 individual studies. These relationships were then compared with hardness/strength experimental data obtained from heat-treated AA6061 and AA7075 tubular specimens. Then, a set of empirical models was developed to calibrate the coefficients of the Holloman and Voce type hardening laws by utilizing the measured hardness and strength values. Finally, to assure the validity of the proposed model, Rockwell hardness test, conducted on the bulged AA6061 and AA7075, was simulated. To do so, the generated flow behavior of bulged specimens based on hardness measurement was used as input plastic flow data in Abaqus commercial FE software, and the indentation geometry on bulged Al specimens were then compared to the experiments. Comprehensive linear and second-degree polynomial relationships were regressed on compiled data for ultimate tensile and yield strengths, respectively. Reasonable agreement was achieved between hardness-strength relationships obtained for all Al alloys and processed AA6061 and AA7075 tubular samples, confirming that these relationships are applicable for any Al alloys regardless of product type and process design. Finally, although both Holloman and Voce type hardening laws gave reasonable estimation of flow behavior in Al tubular specimens particularly at high strain values, Voce model provided a better estimation in comparison to Holloman hardening law. The FE analysis of Rockwell hardness test confirmed that the proposed hardness-strength-hardening law relationship based on Voce type hardening rule was sufficiently accurate in predicting the flow curve in bulged 6061 and 7075 Al alloys.

The mechanical properties and microstructure of 7075 aluminum alloy during the two-stage aging process have been studied by means of Rockwell hardness test, tensile test, X-ray diffraction, scanning electron microscopy, transmission electron microscopy (TEM) and high-resolution TEM. The results illustrated that there existed double peaks for both the hardness and strength in 7075 aluminum alloy during the two-stage aging process. Furthermore, the aging time to reach the second peak was obviously shortened compared to single-stage aging process. At the first peak aging state, the strengthening effect of the alloy was dominated by high-density GP zones, but η′ phase (MgZn2) was mainly the strengthening phase at the second peak aging state.

In accordance with the requirement of manufacturing dies quickly and economically, a hybrid forming method of stamping dies for automobile panels is proposed. The method combines digital patternless casting and high-power laser cladding. An experimental study is conducted on the hybrid forming process and its trial production and application in the manufacturing of stamping dies for typical panels. Results prove that the laser cladding layer exceeds HRC60 (Rockwell hardness) and thus meets the production efficiency requirement of automobile dies. The rate of defects is well controlled. Compared with traditional technology, this technology has remarkable advantages and advancement.

Water-atomized powders of M3:2 high-speed steel (HSS) were blended with B4C and consolidated by cold press sintering. With the addition of B4C (~ 0.2 vol.%), satisfactory mechanical properties were achieved for HSS by sintering at a temperature as low as 1190 °C [e.g., 53.2 ± 0.2 in the Rockwell hardness (HRC) and 3074 ± 56 MPa in bending strength]. High relative density (98.5%) and good strength were attributed to the mechanism described as follows: First, the atoms of boron and carbon escaped after the reaction between B4C and iron matrix. Then, the sintered HSS was strengthened by boron atoms while they were distributed in M6C or MC carbides and iron matrix. Second, a plenty of M6C carbides were formed due to the release of carbon atoms. As a result, the value of solidus temperature was reduced. In addition, mechanical properties were greatly improved by heat treatment (quenching and tempering) (e.g., 61.2 ± 0.3 in HRC, 4356 ± 64 MPa in bending strength, and 42.3 ± 0.5 MPa m1/2 in fracture toughness, respectively).

In the present study, a novel chemical treatment has been introduced for the extraction of nano-cellulose fibers (NCF) from waste sugarcane bagasse and applied as a reinforcement material to enhance the mechanical, corrosion and tribological properties of epoxy-based bio-nanocomposites. The experimental design was selected as per central composite design (response surface methodology) to optimize the effect of fiber concentration (2.93 to 17.07 wt.%) and sonication time (47.57 to 132.43 min). From the analysis of variance (ANOVA) results, it was found that the fiber concentration and sonication played a significant role in the mechanical properties. In order to simultaneously maximize the mechanical properties such as tensile, compression, flexural, impact strength and Rockwell hardness, the optimal values of nanocellulose fiber and sonication time was found to be 10 wt.% and 120 min respectively. From the normal distribution plot, it is found that there is a good agreement between experimental results and developed CCD model. The chemically treated nanocellulose fiber reinforcement in epoxy polymer improved the mechanical, corrosion and wear resistance properties. Total wear rate of chemically treated fibers reinforced epoxy nanocomposites reduced up to 21.67 % when compared with the neat epoxy polymer. The scanning electron microscope analysis on the sugarcane nanocellulose fiber reinforced epoxy nanocomposites revealed good dispersion of nanocellulose in the polymer matrix, which cause for the improved mechanical, corrosion and wear resistance characteristics.

Binding and particle phases are the two important parameters influencing materials properties. In this study, a series of novel W-4.9Ni-2.1Fe-xY2O3 (in weight%) alloys with different Y2O3 contents are prepared by secondary ball milling and spark plasma sintering (SPS) techniques to obtain uniformly distributed γ-(Ni, Fe) binding phases and finer grains. The microstructure, mechanical, wear resistance, and corrosion behavior of the sintered bodies with different Y2O3 were obtained by x-ray diffraction, scanning electron microscopy, Rockwell hardness tester, friction wear tester, and three-dimensional profile instruments. The results showed that a certain addition of Y2O3 led to refined grains and uniformed microstructures; but, if excessive, a weak grain refinement would be appeared. Moreover, the grain size tends to be stable with enhancing of the Y2O3 content. Considering properties such as density, hardness, compression yield strength, grain size, and uniform distribution of tungsten hard phase and γ-(Ni, Fe) binding phase, the comprehensive optimal amount of 0.7 wt.% of Y2O3 was attained for the alloy. Meanwhile, the SPS sintered body also exhibited the best friction, wear behavior, and corrosion resistance in 3.5% of NaCl solution.

Microstructure and properties of the alloys could be changed by heat treatment process. In this work, effect of quenching temperature on the microstructure of Al-bearing high-boron high-speed steel (AB-HSS) was investigated by means of optical microscopy, scanning electron microscopy and X-ray diffraction. Hardness and wear resistance of AB-HSS at different quenching temperatures were tested by rockwell hardness tester, microhardness tester and wear tester, respectively. The experimental results indicate that the microstructure of as-cast AB-HSS is mainly composed of pearlite, ferrite, M2B-type boride and M23(C, B)6-type borocarbide. After quenched treatment, the matrix transforms into the martensite and the type of boride has no obvious change. The morphology of boride changes from continuous network and fish-bone to isolate shape and granular distribution. As quenching temperature increases, the hardness of alloy increases. The hardness reaches 65.1 HRC when quenching temperature is 1110 °C. The wear resistance of alloy gradually increases with the increase in quenching temperature. The wear resistance is the best when the quenching temperature reaches 1110 °C.

This work examines the effect of heat treatment parameters such as the cooling velocity and the quenching fluid nature on the structural, Rockwell hardness and thermal properties of XC48 steel. The studied specimen is a cylinder of 3 cm diameter and 10 cm length, and the used quenching fluids are oil, water and air. The investigation shows that the XC48 hardness varies from 18 to 58 HRC through the used quenching fluid and decreases along the length of the specimen contrary to the thermal conductivity and thermal diffusivity, which are primarily in the order of 36 W m−1 K−1 and 0.125 cm2 s−1 respectively, and which increase with the quenching velocity. A correlation between these thermo-mechanical properties such as the hardness and the thermal conductivity is realized to obtain a new nondestructive technique permitting to determine the mechanical hardness without measuring it. This technique is of an overwhelming importance and can be used in the industrial and research fields.

The aim of this investigation was to compare the microstructural, mechanical and electrochemical corrosion characteristics of 38CrSi steel with widely used AISI 4140 steel under various heat treatment processes to widen its field of applications. Experimental steels 38CrSi and AISI 4140 were subjected to austenitizing at 900 °C for 30 min followed by annealing, quenching in oil and quenching followed by tempering at 400 °C for 120 min. Microstructure of 38CrSi and AISI 4140 steels was characterized by light optical and scanning electron microscopy. Tensile, Charpy impact toughness and Rockwell hardness testing techniques were used to evaluate the mechanical properties. Electrochemical corrosion behavior was evaluated by a Tafel scan in tape water. Results show that microstructure of both steels comprised of ferrite and pearlite after annealing, packets and blocks of lath martensite with retained austenite after quenching and tempered lath martensite with retained austenite after quenching, and tempering with varying grain size distribution and volume fractions of different phases. Hardness and tensile properties of both steels varied in quite identical manner, while impact toughness of both steels varied in inverse manner. 38CrSi steel was found to be brittle, while AISI 4140 steel exhibited excellent properties under all heat treatment processes. In 38CrSi, the corrosion rate decreases as compared to the as-received sample from 0.515 to 0.486 mpy in quenching and tempering heat treatment, while in AISI 4140 steel the corrosion rate decreases during quenching from 0.620 to 0.472 mpy.

Magnesium alloys are light weight and exhibit good recyclability but suffer from low hardness and wear resistance. In this study, the hardness and wear resistance of AZ31 magnesium alloy were improved by depositing diamond-like carbon (DLC) films as hard protective coatings using ion-beam-enhanced deposition with various CH4/H2 ratio, gas flow rates and accelerating voltages. The supporting effect of the magnesium alloy was enhanced by the production of a graded interfacial layer which is composed of film atoms and substrate atoms. The composition and mechanical properties of the DLC coatings were characterized using scanning electron microscopy (SEM), Raman spectroscopy, Rockwell test and nano-indentor. The tribological properties of the coating were also investigated using a frictional surface microscope with an in situ observation system and friction force measurements. The DLC films were characterized by a lower intensity ratio of the D-peak to G-peak (ID/IG), higher hardness, and improved tribological properties when deposited at a lower accelerating voltage (6 kV). At the CH4/H2 ratio of 1:99 and 6 sccm/6 kV, minimum ID/IG values of 0.62, relatively low friction force value of 0.12 N, and a maximum hardness of 4056HV were attained respectively. In addition, the DLC film exhibited improved wear resistance and a shallower wear track at this condition.

In this investigation, mechanical properties, failure mechanism, and microstructural features of 6061-T6 and 6061-T4 aluminum alloy plates welded by gas metal arc welding in pulsed metal transfer mode are analyzed. Samples were submitted to a standard heat pretreatment of solubilization at 350 ∘C (T4) which revealed the presence of β″-phase (Al, Mg, Si) precipitates dissolved in the aluminum matrix. The size of precipitates grew up from 3.58 to 4.12 μ m after the solubilization, while the volumetric fraction increased from 2.35 to 2.97% and Rockwell hardness decreased from 82 HR15T to 61 HR15T as a consequence of the pretreatment process. After welding, the best mechanical properties in tensile strength were found in 6061-T4 samples, reaching 117.48 MPa, in contrast to the 6061-T6 sample processed with similar conditions which reached 73.57 MPa. X-ray energy dispersive spectroscopy revealed the presence of Mg and Cu, which are precursors of the formation of the hardening β″-phase, which dissolves in the diffusion zone leading in lower hardness regions due to the diminishing of precipitates and the increase in the grain size; this phenomenon causes a ductile failure mechanism. The best parameters in this study were identified for the sample welded with a current of 250 A, a heat flux of 1.084 KJ/mm and 294 mm/min as feed rate.

β-Titanium (Ti) alloys have applications in several industries (e.g. aerospace, automotive, and biomedical) where material performance requirements vary widely. To tailor the microstructure and mechanical properties of β-Ti alloys for various applications, it is critical to understand the influence of individual alloying elements. Toward this goal, we investigated the effect of individual alloying additions on the microstructure and resultant mechanical properties of four model β-Ti alloys: Ti-12Cr, Ti-12Cr-3Al, Ti-12Cr-1Fe, and Ti-12Cr-1Fe-3Al (wt.%). The microstructures of these alloys were studied using x-ray diffraction, electron microscopy, and atom probe tomography. The mechanical properties were analyzed via Vickers and Rockwell hardness measurements and tensile testing. The addition of 1 wt.% Fe resulted in an approximate 5% increase in elongation-to-failure (ef), while the addition of 3 wt.% Al did not appear to significantly affect ef. The addition of Fe and Al decreased the yield and ultimate tensile strengths.

The W–4.9Ni–2.1Fe–xDy2O3 heavy alloy was fabricated by high-energy ball milling and spark plasma sintering (SPS) technique, and the microstructure, mechanical and friction behavior and anti-corrosion ability were investigated by scanning electron microscope (SEM), Rockwell hardness tester, X-ray diffraction (XRD), reciprocating friction and wear tester, electrochemical station, etc. The results show that the trace Dy2O3 particles, which mainly distributes in the W–M (tungsten-matrix) interface and the tungsten matrix phase, can dramatically decrease the tungsten grain size and the amount of O and P impurities aggregating in the interface, promote the γ-(Ni, Fe) bonding phase and tungsten particles uniform distribution, and increase the relative density, hardness, and wear and corrosion resistance properties. But the excessive Dy2O3 addition can make the inhibition effect weaken, resulting in the decrease in the comprehensive performances of the alloy. So, the amount of Dy2O3 should be appropriate. When the adding amount of Dy2O3 particles is 0.7 wt%, the comprehensive performances of the heavy alloy are the best.

The microstructure, hardness and sliding wear behavior of bainitic steel containing 1.0–2.5% Si were investigated by means of the optical microscope, the scanning electron microscope, the X-ray diffraction, energy-dispersive spectroscopy, Rockwell hardness tester, microhardness tester and M-200 wear tester. The results show that the as-cast structure is mainly composed of acicular lower bainite and retained austenite. As the silicon content increases, the bainitic lath is refined, the retained austenite content is reduced, and the hardness tends to increase. After normalizing at 900 °C, the microstructure of the steel is mainly acicular lower bainite and film-like retained austenite. With the increase in Si content, the bainite needle is more refined, the retained austenite content is reduced, and the hardness is increased by about 20%. In as-cast and normalizing condition, as the silicon content increases, the wear loss of cast steel is reduced, and the wear resistance is improved. The wear loss of normalizing steel is obviously smaller than that of as-cast steel.

Micron sized Manganese particles of different percentage (0.2, 0.4, 0.6 and 0.8 wt%) have been added during the melting phase of the Al-2wt%Zn-2wt%Mg alloy. Mechanical testing and microstructural characterization have been performed to investigate the change incorporated by the addition of Mn particles. It was found that with the addition of Mn particles the ultimate tensile strength (UTS) of the alloy gradually improved up to an optimum percentage followed by rather reduction for the higher percentages. For optimum percentage of Mn (0.6% Mn) maximum 14% improvement in the UTS was achieved. The percentage of strain before fracture followed opposite trend to the UTS. Optical microscopy and scanning electron microscopy (SEM) of the alloys indicated that optimum percentage of Mn particles provided the microstructure with uniform dispersed second phase in the alloy matrix. These dispersed second phase effectively acted as a barrier to the dislocation motion, and consequently, improved the strength of the alloy as well as reduced the total elongation before fracture. Rockwell hardness test result showed that addition of Mn particles significantly improved the hardness of the alloy with successive addition. The hardness of the base alloy found to be improved by maximum up to 47.3% for 0.8% of Mn particles.

In the present work, an experimental investigation and characterization of Functionally Graded Materials (FGMs) is carried out. The Nickel (Ni) and Titanium dioxide (TiO2) materials are taken as principal materials and the powder metallurgy technique is used for the preparation of specimens. The Nickel powder has a particle size of 20 μm with more than 99% purity and Titanium dioxide powder having 35 μm particle size with more than 99% purity is used for this study. The FGM specimens are prepared with five layers, with pure Nickel on one side and pure Titanium dioxide on opposite side of the specimen; and the three intermediate layers comprising of mixture of Nickel and Titanium dioxide. The five layered FGM samples are prepared with one inch diameter round die and the compacted samples are heated up to 1200°C in an inert gas (argon) atmosphere. The microscopic result shows that the microstructure of Ni/TiO2 FGM has varied layer-by-layer and the interface between the layers are observed. As a part of mechanical characterization, both green and sintered FGM sample densities are measured for each layer of the sample. The Rockwell hardness test method is used to find the hardness of the each layer in the samples. Linear shrinkage of the specimen is calculated with the help of green sample dimensions. The Compression test is conducted on the sintered specimens by using universal testing machine; stress-strain behaviour and maximum stress reported.

Concrete has been widely used in pavements and buildings, and it is necessary to increase its hardness in order to resist deformation, penetration, and abrasion for these applications. This study explores the effects of addition of CuO and/or TiO2 nanoparticles on the hardness of cement mortar. Scanning electron microscopy, X-ray diffraction, energy dispersive spectroscopy, and Rockwell hardness testing were used to study the microstructure, chemical and phase composition, and hardness. The results showed that the addition of nanoparticles can effectively improve the hardness of cement mortar by improving the microstructure and hydration process. This is because they offer additional nucleation sites for hydrates to deposit on, producing a more compact microstructure with finer grains. As the concentration of nanoparticles added increases, the enhancement is more obvious and stable. However, after the concentration reaches its maximum level, the hardness starts to decrease due to the formation of defects, mainly voids, caused by excess nanoparticles. CuO and TiO2 nanoparticles show similar effects on the microstructure and hardness, but the addition of both CuO and TiO2 nanoparticles with similar amounts shows denser microstructure and higher hardness as they densify the composites.

The evolution of the microstructure and mechanical properties of a powder metallurgical (PM) high-speed steel (HSS) were investigated using a series of tempering times. A near Baker–Nutting (B–N) orientation relationship (OR) between the MC carbide and martensitic matrix was detected, while no OR between the M6C carbide and matrix was observed. The average grain size of the investigated alloys was approximately 4 to 6 μm, which was slightly larger than the thermodynamic calculated grain size of 2 μm. The results indicated that the Rockwell hardness, compressive strength, and in-situ nano-hardness of martensite decreased as the tempering times increased. After quadruple tempering, the fracture strain, compressive strength, and flexural strength declined. Triple tempering contributed to the superior combination of compressive strength, fracture strain, Rockwell hardness, and flexural strength of 3245 MPa, 30.6 pct, HRC 62.2, and 2094 MPa, respectively. The investigated alloys demonstrated strong susceptibility to cracks. The results of this study could provide useful information for the application of this HSS.

Enhancing the strength and thermal conductivity of A319 aluminium alloy powertrain components can reduce instances of premature failure, by resisting or alleviating thermal stresses that develop during engine operation. These properties can be manipulated theoretically through microstructural control, for example via variation of the alloy solidification rate. Although increasing solidification rate has been observed to achieve improved mechanical properties, its influence on thermal conductivity is yet unclear. In this study, A319 alloy was cast with a succession of solidification rates by using a permanent mould preheated to a range of temperatures. The as-cast samples were comprehensively characterized in terms of their dendritic structures, secondary phase morphologies and area fractions, porosity, ultimate tensile strengths and Rockwell hardness values, and thermal conductivities, the latter of which was measured via the transient plane source method. The results demonstrated that refinement and other changes in microstructure with increasing solidification rate promoted no noticeable variation in thermal conductivity, despite improvements to strength and hardness. Thus, solidification rate can be controlled effectively to design the mechanical properties of A319 components without detriment to its thermal properties.

As one of the new additive manufacturing processes, electron beam melting (EBM) has seen its promising potential in the fabrication of metal matrix composites (MMCs) components with complex geometries. In this work, WCP/NiBSi MMCs were fabricated by EBM and plasma-transferred arc welding (PTAW) for a comparative study. The microstructures of both samples were examined using a scanning electron microscope (SEM) equipped with an electron backscattered diffraction (EBSD) detector. The macrohardness was tested using a Rockwell hardness method (Type C), while the microhardness was measured using different loadings (0.5–1.0 N) based on different phases. The anti-abrasion performance was tested as per the ASTM G105 standard. The corrosion behavior of the MMCs was also assessed by potentiodynamic polarization. The results indicate that the EBM bulk and the PTAW cladding MMCs exhibit different microstructures due to the different local solidification conditions. This is believed to lead to the varied mechanical properties and corrosion resistance of the MMCs, and the possible mechanisms were also discussed.

A new type of high boron-high speed steel (HB-HSS) with different boron content was selected for oil quenching at 1050 °C, and different temperature of tempering treatment was chosen. By using optical microscopy, scanning electron microscopy, X-ray diffraction, Rockwell hardness tester, red hard treatment and wear test, the effects of heat treatment on microstructure and properties of HB-HSS were investigated. The experimental results indicate that the quenching microstructure of HB-HSS consists of α-Fe, M2(B, C), M7(B, C)3 and a few of M23(C, B)6. When the tempering temperature is lower than 500 °C, the shape of carboborides will change from discontinuous sheet to continuous net, and the uniformity in microstructure is improved, and the hardness is not changed during the process. When the tempering temperature is higher than 500 °C, the continuous net of M2(B, C) is recovered. When the tempering temperature is higher than 600 °C, the microstructure of HB-HSS get thickened because of overheating, and the hardness get significantly reduced. With the increase of tempering temperature, the weight loss of the sample is decreased, and the wear resistance of the sample is increased. When tempering temperature exceeds 500 °C, the weight loss of the sample has an obvious increase and its wear resistance decreases. The wear resistance of the sample decreases after the red-hardness treatment. The wear loss is about 8.4 mg when the boron content is 2.0% and the tempering temperature is 500 °C, which is the best of test samples.

Effects of N and Zr on the as-cast microstructure and properties after annealing of high-speed steel (HSS) were investigated by using electronic probe micro-analysis, Rockwell hardness test, X-ray diffractometry and differential scanning calorimetry with combination of microstructure analysis. The results indicate that the addition of N and Zr will refine the eutectic structures and enhance the stability of carbides which are mainly MC, M2C and M7C3. The coarse dendritic structures decrease significantly and most of the carbides are distributed in the microstructure uniformly. Moreover, a kind of Zr–Si compound which only exists in VC is discovered, and this new phase is speculated to be related with the spheroidization of VC. The annealing process is set up to 6 different time periods which are 1, 3, 6, 10, 15 and 20 h, respectively. In different annealing processes at 750 °C which is lower than austenitizing temperature, the addition of N and Zr makes the decrease of hardness more obvious and restrains the precipitation of secondary carbides with the extension of time. Moreover, when the annealing time reaches 20 h, some clusters appear in the matrix of the two samples, and the density of clusters in HSS1 is lower, but the matrix of HSS1 contains more C and alloying elements which indicate more carbides precipitate.

Based on the power-law stress–strain relation and equivalent energy principle, theoretical equations for converting between Brinell hardness (HB), Rockwell hardness (HR), and Vickers hardness (HV) were established. Combining the pre-existing relation between the tensile strength (σ b ) and Hollomon parameters (K, N), theoretical conversions between hardness (HB/HR/HV) and tensile strength (σ b ) were obtained as well. In addition, to confirm the pre-existing σ b -(K, N) relation, a large number of uniaxial tensile tests were conducted in various ductile materials. Finally, to verify the theoretical conversions, plenty of statistical data listed in ASTM and ISO standards were adopted to test the robustness of the converting equations with various hardness and tensile strength. The results show that both hardness conversions and hardness-strength conversions calculated from the theoretical equations accord well with the standard data.

The effect quenching and tempering by different regimes on Rockwell hardness and wear processes of grinding balls 50 and 70 mm in diameter made of two melts of chromium-molybdenum cast iron is studied. The heating temperature for quenching is 850, 950, and 1050°C; the tempering temperature is 250, 400, and 600°C. Iron is analyzed in an electron microscope. Diffraction patterns are obtained. A model of cast iron wear is suggested and compared to the Davis model and to experimental results. An optimum heat treatment regime is proposed.

Copper–chromium carbide composites containing a carbide phase of 20–30 vol% were obtained with the use of solid- and liquid-phase mechanosyntheses, followed by magnetic pulse compaction (MPC) and spark plasma sintering. The morphology, structural-phase composition, density, hardness and electrical conductivity of the composites were investigated. The structure of composites obtained by MPC represents regions of copper matrix hardened by superfine carbide precipitates surrounded by a layer of chromium carbide. In the composites obtained by spark plasma sintering, the copper matrix hardened by superfine carbide precipitates was divided into areas surrounded by a copper–chromium layer. A composite obtained by the MPC of the powders synthesized using solid-phase mechanosynthesis (MS) (copper, chromium and graphite) had the highest values of Vickers microhardness (4.6 GPa) and Rockwell hardness (HRA 69). The best value of electrical conductivity (36% IACS) was achieved using liquid-phase MS (copper, chromium and xylene) and spark plasma sintering. Liquid-phase MS is the only way to synthesize the powder with a small amount of the carbide phase and without contamination.