Increase In Hardness Of Material Research Articles

Niobium‐Carbide‐Enhanced Wear Performance of High‐Carbon Steels

In this article, the multifaceted challenges of abrasive wear are explored, delving into its impact on components across diverse industries such as automotive, aerospace, mining, manufacturing, and energy production. The introduction of hard eutectic niobium carbide (NbC) networks into a high C martensitic steel and its effect on abrasive wear properties specifically is investigated. Four ingots are casted with Nb contents of 0.01, 0.25, 0.5, and 1.0 wt% and a base compositions of Fe–1.0C–0.96Mn–0.22Si–0.26Cu–0.11Ni–0.50Cr–0.005V–0.012Nb to determine the influence of eutectic NbC on hardness and wear resistance. Microstructural evaluation performed using scanning electron microscopy, electron dispersive spectroscopy, and X‐ray diffraction reveals that the eutectic NbC networks are broken up and distributed in bands within the microstructure upon hot‐rolling. A general increase in material hardness and wear resistance with an increase in Nb content is observed as measured by dry sand/rubber wheel (DSRW) testing. Nb alloying leads to a 65% decrease in DSRW mass loss between the 0.01 and 1.0 wt% Nb alloys at an approximate rate of 6% per every 0.1 wt% Nb added.

Application of magnetic‑pulse treatment in electrode arc welding of AD1N alloy

The paper proposes and experimentally tests a new method of welding aluminum alloys with simultaneous magnetic‑pulse treatment (MPT) of the liquid and solidifying metal of the welding pool. The results of investigations on semi‑automatic welding of AD1N aluminum alloy with MPT of the molten pool are presented. The influence of welding and magnetic‑pulse treatment modes on the structure and physico‑mechanical properties of the weld zones is investigated. The research data is presented in the range of discharge energy variation from 250 to 500 J and pulse numbers from 23–24. The results show that the influence of the pulsed magnetic field with discharge energy of 350 and 500 J leads to an increase in material hardness. It is shown that welding with simultaneous MPT in these modes results in structure refinement and the formation of a textured zone with elongated grains at the border with the heat‑affected zone.

Homogeneity, metallurgical, mechanical, wear, and corrosion behavior of Ni and B4C coatings deposited on 304 stainless steels developed by microwave cladding technique

The microwave cladding technique for depositing Ni and 10 % B4C coatings on 304 stainless steel has yielded significant advancements in material properties and performance. The key findings of this study revealed remarkable improvements, including a 43.33% increase in material hardness, indicating enhanced wear resistance and mechanical properties. This improvement was attributed to the uniform distribution of B4C and Ni on the cladding surface, ensuring a consistent interfacial layer developed between SS 304 and the cladding surface without cracks and porosity. Microstructural analysis at 500× magnification unveiled an impressive 2233.35 grains per square inch, showcasing the refined grain structure achieved during the cladding process. Wear testing demonstrated a low wear rate of 0.00308 mm³/m and a favorable coefficient of friction of 0.1981, confirming the material's suitability for applications with demanding frictional conditions. Furthermore, the corrosion behavior of the coated 304 stainless steel was assessed, revealing a minimal corrosion weight loss of only 0.42 mg for the Ni and 10% B4C coated sample. The presence of various carbide phases, such as Cr2C, Cr23C6, Cr7BC4, Fe5C2, and Fe23B6, within the cladding further contributed to the material's enhanced mechanical and wear properties.

A mathematical model for erosive abrasive wear analysis by using abrasive size and material hardness

PurposeErosion and abrasion are the prominent wear mechanisms reducing the lifetime of machine components. Both wear mechanisms are playing a role meanwhile, generating a synergy, leading to a material removal on the target. The purpose of study is to create a mathematical expression for erosive abrasive wear.Design/methodology/approachMany factors such as environmental cases and material character have an influence in erosive abrasive wear. In the work, changes in abrasive size and material hardness have been analyzed. As an abrasive particle, quartz sand has been used. All tests have been done in 20 wt.% slurry. Heat treatment has been applied to different steel specimens (steel grades C15, St 37 and Ck45) to change hardness value, which ranged from 185 to 880 Vickers hardness number.FindingsAfter the four-hour test, it is determined that by an increase in abrasive size and decrease in material hardness, wear rate increases. Worn surfaces of the targets have been examined to figure out the wear mechanisms at different conditions under scanning electron microscopy. The results indicate that by an increase in material hardness, the number and diameter of micro-craters on the worn surfaces decrease. The diameters of micro-craters have been about 3–8 µm in hard materials and about 120–140 µm in soft materials.Research limitations/implicationsIt is determined that by an increase in abrasive size and decrease in material hardness, wear rate increases. The results indicate that by an increase in material hardness, the number and diameter of micro-craters on the worn surfaces decrease.Practical implicationsThe study enables to indicate the dominant factor in worn steel used in mechanical components.Originality/valueAfter analyzing the test results, a novel mathematical expression, considering both abrasive size and material hardness, has been developed.

Effects of annealing in air on microstructure and hardness of hydroxyapatite ceramics

In this study, microstructural variation of hydroxyapatite (HAp) ceramics upon thermal treatment in air at different temperatures was investigated by x-ray diffraction patterns, Raman and x-ray photoelectron spectroscopies. The results revealed a significant dependence of the microstructure of nonstoichiometric HAp on temperature, because of the competition between hydroxylation and different kinds of dehydroxylation at different temperatures, and a gradual increase in material hardness with annealing temperature because of structural reconstruction. In summary, a suitable thermal treatment can effectively tailor microstructure and defect contents, as well as chemical composition and mechanical hardness of HAp ceramics.

Influence of Hot Deformation on the Precipitation Hardening of High-Strength Aluminum AA7075 during Thermo-Mechanical Processing

The aim of this work was to investigate the effect of hot deformation on the aging behavior of precipitation-hardenable aluminum alloy AA7075 within a novel thermo-mechanical forming process, in order to gain insight into its precipitation kinetics. For this purpose, the material was formed at 420 °C after undergoing solution treatment to different strain levels ranging from 2% to 10% to obtain different dislocation densities. After undergoing hot deformation, aging at 120 °C with different parameters was carried out to improve the material hardness. The resulting material properties and microstructure evolution were characterized afterward using hardness measurements and a transmission electron microscope (TEM). TEM investigations revealed the formation of very fine particles for the material formed at 2%, as well as at 10%, of formed material, which act as effective barriers to dislocation motion. It was found that the response of artificial aging on the deformation degree in hot forming was less than expected due to the thermally activated mechanisms, leading to a decrease in dislocation density. Therefore, a dramatic increase in material hardness with the increase in hot deformation was not observed.

Impact of the hardness on the selected mechanical properties of rigid polyurethane elastomers commonly used in suspension systems

The paper presents the results of experimental research on polyurethane materials used in car suspension systems. Taking into account the frequency of maintenance and the number of replacement metal-rubber bushings on the market, the authors considered it reasonable to carry out their tests of materials with different hardnesses of 80 and 90 ShA used in conventional applications as well as in sports vehicle suspensions. Two types of PUR material were produced for this purpose. The materials were subjected to mechanical tests; tearing, tensile, compression, abrasive wear. Finally, a model of the polyurethane bushing was created and subjected to fatigue tests. As a result, several significant findings were made regarding the influence of hardness on selected mechanical properties. As evidenced by the results of the investigations, even a small increase in material hardness significantly affects changes of fatigue parameters and material fracture-related parameters in general. The pilot results can serve as reference values in the design of anti-failure bushing systems.

Surface Hardening of Aluminium Alloy with Addition of Zinc Particles by Friction Stir Processing

Abstract Mechanical alloying can be carried out by a method known as friction stir processing, whereby solid Zn particles in a solution are distributed onto an aluminium alloy plate. The aim of this study was to determine the effects of a volume of Zn particles on the mechanical and physical properties of aluminium 1xxx alloy that had been subjected to friction stir processing. The specimens were plates composed of 1xxx series aluminium. A groove, measuring 12 mm in diameter, was pierced to various depths, and the Zn particles in these containers were then subjected to friction stir processing using a pin-less tool with a diameter of 15 mm. The results showed that the highest hardness was found in the uppermost layer of the workpiece, and this gradually decreased with thickness. An increase in the amount of Zn particles caused an increase in material hardness. The highest hardness of 87.1 HV in the friction stir-processed AA1100 was obtained at the highest volume of Zn compared to the hardness of 44.5 HV, which was obtained for the specimen without the addition of Zn.

INFLUENCE OF MATERIAL HARDNESS AND PARTICLE VELOCITY ON EROSIVE WEAR RATE

Many parameters such as medium conditions and material properties are effective on erosiveabrasive wear rate. In this study, effect of particle impact velocity and hardness of material on wear rate and wear mechanism was investigated. All tests were carried out in 20% sand-water mixture. Impact velocities of the particles were ranking between 2.04 m/s and 4.76 m/s. Hardness values of St 37 and Ck 45 steels were changed by applying different heat treatments. After wear tests it was concluded that by an increase of impact velocity and decrease of material hardness, wear rate increased. This increase was by soft materials more dominant than by hard materials. After morphological investigations it is concludedthat by an increase of material hardness, number and size of craters on the surface after erosion tests decreased. By using experimental test results, a new mathematical formulation was developed to emphasize the relation between impact velocity and material hardness on wear rate.

RETRACTED ARTICLE]: Load Dependent Wear Analysis of Manganese Steels - Influence of Al Content

In this paper influence of load on change in weight loss (mg), hardness and wear transition of 0.12 wt.% Al-Mn-steel (Steel A), 0.35 wt.% Al-Mn-steel (Steel B) and Mn-steel (Steel C) has been examined. With the increase in load these steels shows remarkable decrease in weight loss due to change in surface microstructure from austenite to e or ά - martensite which results in increase in hardness of material. With the increase in hardness transition in wear mechanism has been noticed. In future aspect these steel would prove to be better material as wear resistant liner in many industrial application.

The investigation of the influence of thermomechanical treatment of the material of rotary cutter bit toolholders on its hardness

The causes of failure of the tangential rotary cutter bits of the road header during stonedrift in rocks of medium strength are analyzed in the article. It was revealed that the most typical cause of failure of cutter bits is premature wear of the toolholder (body) of the cutter bit. It is well known that the most effective way to improve the wear resistance is to increase hardness. The influence of the thermomechanical treatment of the material of the cutter bit toolholder on its hardness is studied. It was established that the thermomechanical treatment of the cutter bit toolholder material results in the increase of its hardness. It was found that the increase of material hardness is proportional to the increase of material strain intensity during thermomechanical treatment. It was concluded that the use of thermomechanical treatment can lead to the increase of both the hardness and wear resistance of the cutter bit material.

Correlation of Tribological Properties of Titanium Alloys with their Microstructures

In general titanium alloys are associated with biomedical applications due to their unique properties such as: high biocompatibility, high strength to density ratio. They have been commonly used as a prosthetic material. However the microstructural development by heat treatment, directly correlated with the changes in mechanical properties of the material, allows us to consider these alloys as components of machines. One of the main properties of machine components are tribological properties. Knowledge of tribological properties of the machine elements allow us to determine the parts' viability and improve the functionality of the entire engineering system. Titanium alloys are characterized by the low wear resistance caused by chemical reactivity and easy formation of adhesion joints. Intensive adhesive wear of this material is associated with the strong degradation of the material surface. To determine the influence of microstructure on the tribological properties of titanium alloys, dry sliding wear test was performed. The materials for the investigations were five titanium alloys. The tribological test was performed with a load of 100 N for 2000 s on a 500 m distance. The microstructural observations were performed by light microscopy, in addition the wear mechanism was also investigated and for each sample the mechanism of wear was defined. For this type of tribological test a small proportion of adhesive wear was observed. The main mechanisms of wear were microgridding and microcutting. The increase of material hardness does not seem to impact on the increase of average friction coefficient of the samples. Increase of friction coefficient corresponds to the decrease of mass loss for the titanium alloys.

Effect of carbonation on the linear and nonlinear dynamic properties of cement-based materials

Carbonation causes a physicochemical alteration of cement-based materials, leading to a decrease of porosity and an increase of material hardness and strength. However, carbonation will decrease the pH of the internal pore water solution, which may depassivate the internal reinforcing steel, giving rise to structural durability concerns. Therefore, the proper selection of materials informed by parameters sensitive to the carbonation process is crucial to ensure the durability of concrete structures. The authors investigate the feasibility of using linear and nonlinear dynamic vibration response data to monitor the progression of the carbonation process in cement-based materials. Mortar samples with dimensions of 40×40×160 mm were subjected to an accelerated carbonation process through a carbonation chamber with 55% relative humidity and 95% of CO 2 atmosphere. The progress of carbonation in the material was monitored using data obtained with the test setup of the standard resonant frequency test (ASTM C215-14), from a pristine state until an almost fully carbonated state. Linear dynamic modulus, quality factor, and a material nonlinear response, evaluated through the upward resonant frequency shift during the signal ring-down, were investigated. The compressive strength and the depth of carbonation were also measured. Carbonation resulted in a modest increase in the dynamic modulus, but a substantive increase in the quality factor (inverse attenuation) and a decrease in the material nonlinearity parameter. The combined measurement of the vibration quality factor and nonlinear parameter shows potential as a sensitive measure of material changes brought about by carbonation.

Rolling–sliding wear of austempered ductile iron with different strength grades

Austempered ductile irons (ADIs) with three strength grades were matched with high-carbon–chromium bearing steel and the rolling–sliding wear tests under high contact load were conducted on an Amsler type tribotester. During tests the contact surface was cooled by dry compressed air of 0.6MPa to prevent the surface oxidation by heating. The wear properties and behaviors of these friction pairs were investigated. The results show that the wear mechanism is delamination and the delamination of ADIs becomes mild with the increase of material hardness. The friction coefficient of the test pairs increases with the increase of material hardness and the surface microhardnesses of ADIs increase greatly during the tests due to the martensite transformation. The wear rates of three strength grades of ADIs show no obvious difference and the wear rates are influenced by both the material hardness and the friction coefficient.

Axial splitting of circular tubes by means of blast load

This paper presents the results of an experimental investigation on the axial splitting of thin-walled aluminium extrusions by means of blast load. Plastic explosive (PE4) was used to accelerate the circular extrusions onto a cutting die backed by a curved deflector. The apparatus was mounted on a ballistic pendulum to measure the impulse imparted by the explosive. A load cell was used to measure the transient axial load response during the cutting process. Explosive masses, varied from 15 g to 40 g, produced different lengths of cut (28–137 mm) within the extrusion. The specimens, which were made from three grades of aluminium, AA6061-T4, AA6061-T6 and AA6063-T6, had a nominal diameter of 51 mm, a wall thickness of either 1/16″ (1.6 mm) or 1/8″ (3.2 mm) and were 300 mm in length. Similar energy dissipation mechanisms as previously observed for quasi-static and dynamic loading conditions was observed in the blast load testing applications applied in this study. Furthermore, localised plastic deformation and dynamic progressive buckling were also observed which were not noted in previous impact testing conditions. The performance of the circular extrusions was assessed through determination of the mean cutting load, peak cutting load and cutting force efficiency (CFE). The length of cut increased with an increase in charge mass. An increase in material hardness showed a decrease in the overall cut depth and (CFE).

Injection of Thermoplastic Polyurethane to Fix Diamond Beads on Wire Saws

An investigation was reported of the injection of thermoplastic polyurethane (TPU) to fix diamond beads on wire saws. Effects of injection material hardness, injection temperature and dwell pressure on the mechanical properties of three types of TPU plastics were studied and the results showed that with the increase of material hardness, both the 100% Modulus and the tensile strength of TPU were improved, but the rupture extensibility reduced. With the increase of injection temperature, the tensile strength increased but the rupture elongation decreased. To every type of TPU, a minimum injection temperature can be found for an ideal density of TPU.

Grain growth resistance and increased hardness of bulk nanocrystalline fcc cobalt preparedby a bottom-up approach

Bulk nanocrystalline cobalt was prepared from reducing flame-spray-derived cobaltnanopowders exclusively in the face-centred cubic (fcc) modification. Compacts of∼60% density were obtained from uniaxial compression at room temperature andshowed a strong resistance towards grain growth upon subsequent sintering to90% relative density. The nanocrystalline structure remained stable well above1000 °C and resulted in a pore-rich metal with about1015 nanovoids cm−3. These sintered compacts displayed an up to three times higher bulk hardness if comparedto conventional cobalt and local ductility as evidenced from scanning electron microscopyand nanoindentation. The strong grain-growth resistance and consequent increase inmaterial hardness are discussed in respect of the presence of nanovoids, twin boundariesand material contamination.