Increase In Hardness Values Research Articles

Phase transformation pathways in a Ti-5.9Cu alloy modified with Fe and Al

Titanium alloys have been gaining importance in various industries due to their advantageous combination of strength, low density, excellent corrosion/oxidation resistance, and superior mechanical properties at elevated temperatures. Recently, eutectoid Ti–Cu alloys have been explored as promising candidates for advanced processes. This work investigates the effects of Fe and Al on a Ti-5.9Cu alloy using multi-scale characterization techniques. While Fe acts as a β-stabilizing element (despite being a sluggish eutectoid former), Al acts as an α-stabilizer. This work focuses on the effects of combined addition of these elements, studied in different heat treatment conditions. The results show that a fine, equiaxed microstructure is obtained in the binary Ti-5.9Cu alloy, whereas the addition of 2 wt% Fe, or 2 wt% Fe combined with 2 wt% Al to the Ti-5.9Cu alloy deteriorates the effect of grain refinement and coarse, columnar grains result and a small amount of β-phase is retained. Further, the microstructure resulting from the eutectoid decomposition is altered dramatically from a lamellar pearlitic in the binary alloy to a lath-like α-phase with diverse decomposition products in the ternary and quaternary alloys accompanied by increasing hardness values. Evaluation of the α misorientation suggests that a substantial amount of non-Burgers α is present in the Ti-Cu alloy in contrast to the results of the ternary and quaternary alloys. The observed Cu-rich intermetallic compound was identified as Ti2Cu phase with off-stoichiometric composition. Results obtained explain how adding either Fe or Fe and Al leads to substantial hardening.

Investigation of the Effect of Various Ca Content on Microstructure and Mechanical Properties of As-cast ZK60 Magnesium Alloys

The effect of various Ca content on microstructure and mechanical properties of as-cast Mg-6Zn-0.5Zr (wt.%) Mg alloys with hot tensile testing at 345°C were investigated. The alloy was produced with the LPDC method [1]. Microstructural characterization as-cast alloy demonstrated that wt.% Ca content increase, grain size decreases till wt.% 0.8Ca, the further increase affects gradual change in grain size to ~60 µm at 345°C. Therefore, increase in Ca ratio from 0.4 wt% forming to strip-like Mg-Zn intermetallics at grain boundaries, Ca-Mg-Zn ternary phase at grain boundary corners. Dramatical decrease in yield and tensile strength at wt% 1.6Ca addition is 37.6 MPa and 39.7 MPa respectively which is relatively low at 345°C due to the absence of retarded DRX’ed small particles prohibited the grain growth after the TMT process. Conversely, elongation-to-fracture increases were observed as 1.26 at 345°C showing the temperature-dependent texture softening results in improvement of mechanical properties. Wear rate is also affected from wt.% Ca addition so the gradual increase up to 1.2 wt% Ca is 3.70 x 10-3 mm3/m. Similarly, a gradual increase in hardness values was obtained with Ca addition in ZK60 alloy. In this study, the effect of temperature-dependent Ca addition (wt %) on gradual enhancement in mechanical properties was observed at as-cast magnesium alloys.

Comparative Evaluation of Hardness and Energy Absorption of Some Commercially Available Chairside Silicone-Based Soft Denture Liners and a Heat-Cured Soft Denture Liner.

To investigate the hardness and energy absorption of four commercially available chairside types of silicone materials and compare their properties with heat-cured silicone material. The chairside materials investigated were GC reline soft, mucopren soft, sofreliner soft and elite soft relining. The heat-cured polymer silicone material was Molloplast B. All soft lining materials were processed according to manufacturers' instructions. Two properties were investigated. Ten specimens for each test were prepared for each soft liner except for the water absorption and solubility test, for which only five specimens were prepared. The specimens of energy absorption (10 × 10 × 3 mm) were tested using a Lloyd instruments testing machine. Hardness specimens (38 × 38 × 3) were tested using a shore A durometer and were divided into two subgroups; dry and wet storage. The specimens of energy absorption (10 × 10 × 3 mm) were tested using a Lloyd instruments testing machine. Sofreliner soft was significantly softer than Molloplast B. GC reline soft was significantly harder than molloplast B. At high loads, sofreliner soft and elite soft relining was significantly more resilient than molloplast B. Mucopren soft was significantly stiffer than Molloplast B. At low loads, all materials showed similarities in stiffness and resilience; the difference between them was insignificant. After one month of immersion, GC reline and mucopren significantly increased hardness values. In all conditions and at all four-time points, the hardness values for GC Reline soft were the greatest, and hardness values for Sofreliner Soft were the least. Some chairside soft denture lining materials could have similar significant properties to molloplast-B, such as sofreliner soft and elite.

Evaluation of contact angle and mechanical properties of resin monomers filled with graphene oxide nanofibers.

This in vitro study synthesized hybrid nanofibers embedded in graphene oxide (GO) and incorporated them into experimental resin composite monomers to evaluate their physical-mechanical properties. Inorganic-organic hybrid nanofibers were produced with precursor solutions of 1% wt. GO-filled Poly (d,l-lactide, PLA) fibers and scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) characterized the morphology and chemical composition of the spun fibers. Resin composite monomers were developed and a total of 5% nanofibers were incorporated into the experimental materials. Three groups were developed: G1 (control resin monomers), G2 (resin monomers/PLA nanofibers), and G3 (resin monomers/inorganic-organic hybrid nanofibers). Contact angle (n=3), flexural strength (n=22), elastic modulus (n=22), and Knoop hardness (n=6) were evaluated. The mean of the three indentations was obtained for each sample. The normality of data was assessed by QQ Plot with simulated envelopes and analyzed by Welch's method (p<0.05). Overall, SEM images showed the regular shape of nanofibers but were non-aligned. Compositional analysis from EDS (n=6) revealed the presence of carbon and oxygen (present in GO composition) and Si from the functionalization process. The results of contact angle (°) and hardness (Kg/mm2) for each group were as follow, respectively: G1 (59.65±2.90; 37.48±1.86a), G2 (67.99±3.93; 50.56±1.03b) and G3 (62.52±7.40; 67.83±1.01c). The group G3 showed the highest Knoop hardness values (67.83 kg/mm2), and the flexural strength of all groups was adversely affected. The experimental resin composite composed of hybrid nanofibers with GO presented increased hardness values and hydrophilic behavior.

EVALUATION OF MECHANICAL BEHAVIOUR AND EFFECT OF PARTICLE SIZE ON LM26/Gr METAL MATRIX COMPOSITE

In automotive industries, Aluminium cast alloy (LM26) is well-renowned material in the fabrication of pistons for both diesel and petrol engines for its superior casting and mechanical properties. However, diminishing strength at higher temperatures drives metal matrix composites in cast alloys. The present study focused on the impact of naturally available ceramic particles Garnet on the microstructure and mechanical properties of Aluminium cast alloy (LM26). Samples were fabricated with varied Garnet (Wt. % of 3, 6, 9, and 12) by dual step stir casting technique. Two different particle sizes (400µm and 250µm) were incorporated to determine the effect of particle size on composite mechanical behaviour. Scanning electron microscope images unveiled the dissemination of ceramic particles inside the cast alloy matrix. It was found that ultimate tensile strength, yield strength, and impact strength were increased up to a certain Garnet percentage and started diminishing with the rise in particulate fraction for both particle sizes. However, the increase in hardness value indicates the brittleness of Metal matrix composite with the increase in ceramic reinforcement. Validation of Experimental results with theoretical values was also discussed.

Structural characterisation of unique core-shell shaped Al3Ni2/Al3Ni in-situ intermetallic in Al–4Cu-xNi via powder metallurgy (P/M)

An in-situ powder metallurgy technique was used to create Ni–Al3Ni/Al3Ni2 core-shell-shaped aluminum-based intermetallic reinforced composites. The impact of Ni addition on the phase composition, microstructure, and mechanical characteristics of the Al–4Cu-xNi (x = 0, 2, 4, 6, 8, 10 wt%) with respect to various sintering temperatures were examined. Microstructure progression was extensively studied using XRD, and SEM-EDX, and TEM techniques. Initial sintering condition witnessed the proliferation of “Single Core-Shell” structures, comprising Ni as core with Al3Ni2 intermetallic, whereas sample sintered at 620 °C, “Single Core-Shell” and “Double Core-Shell” type of structures containing Al3Ni2, Al3Ni intermetallic were formed between the Al matrix and Ni reinforcements. The 10 wt% Ni addition sample results in substantially high hardness and strength, as compared to the literature, due to the presence of various intermetallics such as Al2Cu, Al3Ni2, and Al3Ni and strong adherence between the formed phase and α-Al matrix. High compressive yield strength of 198.13 MPa and ultimate strength of 410.68 MPa with 24% total elongation was achieved for 10 wt% Ni sample, whereas there was an increase in hardness value of 124.21HV which is 2.4 times higher than that of base Aluminium.

Improved mechanical and electrical properties of copper-aluminum joints with highly aligned graphene reinforcement via friction stir spot welding

This study demonstrates the potential of friction stir spot welding (FSSW) for producing highly aligned graphene configurations in copper-aluminum joints, resulting in improved mechanical and electrical properties. Pure copper and AA6061 sheet were welded with 0.5% graphene nanoparticles dispersed in ethanol drop cast at the interface. Under optimized experimental conditions, adding a graphene interlayer results in a 15.6% increase in maximum shear strength, a 46% increase in hardness value, and a 23% reduction in joint electrical resistance. Transmission electron microscopy confirmed that the laminar flow behavior of the material aligns the graphene nanoparticles parallel to the tool surface direction. The mechanical improvements are attributed to the reduction of grain size and the plastic incompatibilities that arise at the metal-graphene interface. The highly aligned graphene configuration provides more conductive paths and acts as a bridge between grains to reduce grain boundary resistance, reducing electrical resistance. These findings pave the way for exploring the possibilities of utilizing the anisotropic properties of graphene in material joining applications.

Properties of basalt/aramid fiber reinforced hybrid composites compared to carbon fiber composites

AbstractDue to environmental concerns and sustainability issues, researchers have focused on developing novel composite structures in different industries. In this study, aramid and basalt fiber reinforced polymer hybrid composites were designed and manufactured as an alternative material to carbon fiber reinforced polymer (CFRP) composites. The hybrid composites were manufactured with different fiber ratios and stacking sequences to examine the effect on mechanical characteristics. Tensile, impact, hardness, morphological analysis, water absorption, and loss on ignition tests were performed to determine the properties of composites. The test results showed that tensile strength of the hybrid samples was dependent on the ratio and the sequence of fibers, while CFRPs had the highest tensile strength among all samples. Impact test results revealed that B24A24 basalt/aramid fiber hybrid composites had higher energy absorption capability compared to CFRPs at all different fiber ratios. Water absorption test results increment that increasing basalt fiber ratio increased the water absorption capacity of the hybrid composites. In case of aramid fiber in the upper layer, a decrease in ignition loss and increase in hardness values were observed. Through scanning electron microscopy analysis, a weak fiber‐matrix bonding was observed in the structure of hybrid samples in contrast to CFRPs.

The Effect of the Addition of Tuff on the Properties of Brass and Bronze

The article presents studies aimed at identifying the effect of the addition of volcanic tuff, rocks with ceramic properties, on the properties of brass and bronze, which make up the metal matrix of the composite. The research methods included: structure study (microscopic observations using an optical microscope and a scanning microscope), EDS analysis, as well as testing of composites for abrasion and microhardness. The results of the study of samples formed by tuff with brass and bronze show the stability of the structures obtained. Microscopic observations confirm that the distribution of mineral filler particles is uniform. No significant gaps were found between the filler and the matrix. The results of mechanical abrasion tests were the best and the maximum increase in hardness values was achieved with 10% addition of tuff to brass and bronze matrices

Microstructure and Mechanical Characteristics of Ti-Ta Alloys before and after NaOH Treatment and Their Behavior in Simulated Body Fluid

In the present study, the microstructure and mechanical properties of Ti-xTa (x = 5%, 15%, and 25% wt. Ta) alloys produced by using an induced furnace by the cold crucible levitation fusion technique were investigated and compared. The microstructure was examined by scanning electron microscopy and X-ray diffraction. The alloys present a microstructure characterized by the α' lamellar structure in a matrix of the transformed β phase. From the bulk materials, the samples for the tensile tests were prepared and based on the results and the elastic modulus was calculated by deducting the lowest values for the Ti-25Ta alloy. Moreover, a surface alkali treatment functionalization was performed using 10 M NaOH. The microstructure of the new developed films on the surface of the Ti-xTa alloys was investigated by scanning electron microscopy and the chemical analysis revealed the formation of sodium titanate and sodium tantanate along with titanium and tantalum oxides. Using low loads, the Vickers hardness test revealed increased hardness values for the alkali-treated samples. After exposure to simulated body fluid, phosphorus and calcium were identified on the surface of the new developed film, indicating the development of apatite. The corrosion resistance was evaluated by open cell potential measurements in simulated body fluid before and after NaOH treatment. The tests were performed at 22 °C as well as at 40 °C, simulating fever. The results show that the Ta content has a detrimental effect on the investigated alloys' microstructure, hardness, elastic modulus, and corrosion behavior.

Influence of micro-alloying elements and deep cryogenic treatment on microstructure and mechanical properties of S5 cold work shock resisting tool steel

Shock resistance cold work tool steel (S5) has many applications such as blades for sheet cutting, manufacturing of chisel and hammers etc. This Steel has the ability to accommodate residual stresses without premature failure. This work investigates the effect of carbide forming elements; V and Nb on the microstructure and mechanical properties of S5 tool steel. Three heats were prepared with different content of carbide forming elements via vacuum melting and the effect of heat treatment [hardening, tempering and deep cryogenic treatment (DCT) at - 196 °C] on the mechanical properties was investigated. Retained austenite for quenched samples were calculated using X-ray diffraction method, also impact test was used to determine the toughness of all samples after different heat treatment conditions. Microstructure observation showed that the basic structure for the tested samples are tempered martensite for traditional S5 samples and fine tempered martensite for other micro alloyed samples. Scanning electron microscope (SEM) was also used to ensure that the amount of retained austenite have been eliminated or reduced due to deep cryogenic treatment. Hardness (HRC) after quenching process reached 51 HRC, further increase in hardness values has been obtained after DCT due to reduction of retained austenite. The toughness results showed lower values for deep cryogenic treatment than conventional heat treatment samples; this is mainly due to the reduction in retained austenite content.

Modelling Effects of Copper on Microstructure and Properties of Al–Si–Cu Alloys

The combined impacts of copper content, cold working and homogenization in aluminium–silicon alloys were examined using microstructure study, thermodynamic modelling, image analysis and hardness measurement. Two aluminium alloys of varying copper contents were cast in a permanent mould using induction furnace. Microstructural observation revealed the formation of varying amount of intermetallic phases due to the presence of copper. Image analysis confirms the relative changes in percent phase fractions owing to presence of copper as intermetallic phases increases. Al2Cu phase was most favoured with increasing copper. Cold working was performed by reduction of 5%, 10% and 15% of the cast alloys by equal amounts of strain. Hardness measurements indicated increase in hardness values attributed to both higher amounts of copper and cold working. Al2Cu phase was predicted contribute compared to Al7Cu4Ni and Alpha phases. Homogenization at 300°C for 4 hr would suffice to obtain a uniform structure. The reasons for changes in microstructure and mechanical properties for different copper content were established by thermodynamic phase fraction calculation. Higher amounts of copper leads to greater volume fractions of intermetallic phases. Using solidification calculations, it is found that copper in liquid encourages dendrite formation which was also evident from microstructure.

Ffect of melon seed powder on the quality characteristics of cupcakes

Enriching cereal-containing functional foods in the changing food industry is highly attractive. Examining the use of nutrient-rich melon seed powder (MSP), a waste, in bakery products is valuable in sustainability. Within the scope of the study, the use of MSP as an alternative raw material to whole wheat flour (WWF) in cupcake formulation was investigated. Four formulations containing varying proportions of MSP (0%, 10%, 20%, 30%) were evaluated. Depending on the increase of MSP substitution, an increase was observed in the protein, fat and total ash ratios of the cupcakes. The addition of MSP to the product caused browning in the colour of the cupcakes and an increase in hardness values while causing a decrease in their specific volumes. According to the sensory analysis results, while the control cake was the most liked group, it was determined that MSP addition could be used up to 20% in terms of general acceptability and odour in cake production.

Low-speed finite element frontal impact analysis on aluminum alloy bumper made of 6063-T6

In this research, a low-speed impact numerical simulation has been performed on a 6063-T6 Aluminum alloy bumper welded by MIEA technique using ANSYS® LS-DYNA® Workbench™ 19.2, according to the requirements of the Federal Motor Vehicle Safety Standards and Regulations. For the numerical simulation, mechanical properties were obtained from quasi-static tensile tests in 6063-T6 aluminum alloy joints, these joints were manufactured using the MIEA (modified indirect electric arc) technique and a MIG welding process and post-weld heat treatment (PWHT). For the numerical impact simulation, the following parameters have been used: mass of the impactor of 1000 kg, speed of the impactor 4 km/hr and material of the impactor AISI 4130 steel. The simulation study showed that aluminum alloy joints used in bumper beam has excellent mechanical strength under low-speed impact conditions. Among the mechanical properties that have been recovered due to PWHT are the following: it was possible to harden the fusion zone, that is, there was an increase in hardness values from 80 HV0.1 to 98 HV0.1, the heat affected zone was eliminated, obtaining hardness values of approximately 110 HV0.1, a recovery in yield strength (59%) was observed, that is, in welding condition (170 MPa) and welding condition plus PWHT (270 MPa). In terms of tensile strength, a recovery (42%) was observed, going from welding condition (214 MPa) and welding condition plus PWHT (304 MPa). Tensile strength also had an increase ranging from 214 MPa to 304 MPa. This represents an increase of 42 pct. Finally, the simulation showed that the welding zone on the bumper has very good resistance to low speed impact since no permanent deformations were observed, that is, after the impact the bumper returns to its initial position.

SiC Takviyeli Cu-Al-Ni Kompozitlerinin Üretiminde Toz Metalurjisi Yönteminin Kullanımı ve Üretim Sonucunun Karakterizasyonu

Powder metallurgy (PM) is an important production route of alloys and is also important in terms of its properties and economy. This method is suitable for the production of complex and versatile shapes and structures. In this study, it was tried to improve the microstructure and mechanical properties of CuAlNi and CuAlNi-SiC alloys sintered at constant pressing and constant temperature. Composite samples were manufactured by the PM method by supplementing the CuAlNi powder mixture with SiC powders at different weight ratios (2.5%, 5, 7.5 and 10%) at the micron level. Scanning electron microscope (SEM) and optical microscope were used to determine the microstructures of the manufatured samples, and X-Ray Fluorescence (XRF) and X-Ray Diffraction method (XRD) analyzes were used to determine the phases formed in their internal structures. Micro hardness (HV5) was taken to determine the hardness effect. According to the micro structure results, SiC particles were homogeneously dispersed in the structure. Depending on the increasing SiC reinforcement, an increase in hardness values was observed.

INFLUENCE OF WHEEL PROFILE AND HARDNESS ON TRACK STABILITY WITH DIFFERENT STRUCTURE STRUCTURES

For the preparation and during the execution of the work, experimental and theoretical studies were carried out on the influence of the state of the rolling surface profile of the wheelset on the level of interaction forces between the elements of the rail track and rolling stock in operation on the railways of Ukraine. Approaches to modeling the influence of the rolling surface profile of wheelsets on the stability of the wheelset movement and force interaction with the rail track were further developed. Experimental studies of the wear of the rolling surface of wheelsets of rolling stock were carried out, the intensity of their wear depending on the mileage of the locomotive was investigated. Studies of the influence of technical characteristics of hardness in the interaction of rail and wheel and their impact on the service life on the railways of Ukraine are analyzed. After the beginning of operation of wheelsets with increased hardness value, the optimal ratio of hardness of rail and wheel steel was violated. From various sources on the interaction of rails and wheels it is known that the best wear resistance in a friction pair is shown by metals with approximately the same hardness. Based on the data obtained, their analysis was carried out with the development of recommendations for further operation.

Quenching of EN-8 Medium Carbon Steel in Salt Bath of Different Concentrations

Heat treatment of metals and alloys is an important operation in the final fabrication of several engineering parts. Heat treatment and microstructure studies have always been a wide area of research for mechanical and metallurgical engineers. The application of different quenchants for cooling process has further has widened the scope of quenching. This experimental work is concentrated on the microstructure of EN-8 medium carbon steel cast samples when heat treated at different temperatures and quenched in different types of quenchants. The properties of this steel got affected due to sudden quenching. The microstructure of the steel was analysed and it was subjected to Rockwell hardness tests. Increase in hardness value of the samples was determined. The change in microstructure was studied.

An Investigation on Laser shot peened surfaces

The present work is focused on the influence of zinc trivalent plating on laser shot peened AISI 304 stainless steel samples to improve the corrosion resistance of the steel surface. AISI 304 steel samples were heat treated by annealing and polished to perform Laser Shot Peening (LSP) process using Nd-YAG laser functioning at a pulse interval of 10ns with different energies of 200 mJ, 300 mJ and 400 mJ on each sample. The highest magnitude of compressive residual stresses is induced using the pulse density of 2500 pulses/cm2. The laser treated sample was characterized by surface hardness using Vickers micro hardness test and surface morphology using an optical microscope and SEM analysis. The surface hardness of the sample is increased by increasing laser energy. The prepared zinc trivalent is plated using electro deposition on the laser treated surface by maintaining current between 1.5 to 4 amps/Dm2, and temperature between 20 to 40 deg C. MAHR’s roughness tests were performed to find the surface roughness of the sample. The surface roughness has drastically increased on zinc coated samples compared to samples without coating. The Vickers micro hardness test conducted on zinc trivalent plated sample revealed the increase in hardness value of 200mJ by 24% compared with 200mJ sample without coating. SEM and EDAX were carried out to know the changes occurred in the chemical composition of the samples before and after coating.

Modification Structure and their Effects on Physical Properties of Tin Based Lead Free Solder Alloys for Industrial Applications

Soldering properties such as melting temperature and wettability of tin-zinc alloy improved after adding different alloying elements such as indium, aluminum, cadmium and bismuth. Decreasing zinc content (Sn91Zn9) up to 4% (Sn96Zn4 alloy) increased corrosion resistance from -0.847 to -0.530 and decreased corrosion rate from 51.84 to 7.705 mpy. Microstructure of tin-zinc alloy changed with increasing hardness value of it after adding alloying elements. Tin-zinc alloys have lower melting temperature compared to Sn95Sb5, Sn96.5Ag3.5 and Sn99.3Cu0.7 alloys. The Sn90Zn4Bi6 alloy has beast solder properties for electronic industrial applications.

Improvement of Mechanical Behavior of FSW Dissimilar Aluminum Alloys by Postweld Heat Treatments

AA6262 and AA5456 alloys are welded through friction stir weld (FSW) with process parameters of tool speed of 1200 rpm, welding speed of 25 mm/min, and tool angle of 3 degree. A cylindrical shape HSS-13 tool is used to perform the welding process To improve mechanical properties of tensile strength (TS), yield strength (YS), elongation%, hardness, and wear behavior, postweld heat treatment was conducted on the FSW sample at different temperatures from 300°C to 500°C. The influence of heat treatment (HT) changes the material characteristics. It is observed that the maximum TS (209 MPa) and YS (178 MPa) are identified when maintaining temperature 350°C on the FSW sample. The reduction in elongation of as-welded joints is entirely improved by HT, and the elongation percentage is almost increased to 5% when increasing temperature on the heat treatment process, and hardness test results exhibited that the increased hardness value (120Hv) is found at HT-300°C nugget zone distance of 0 to 5 mm range.