Hardness Properties Research Articles

Characterization of Long‐Term Municipal Solid Waste Constitutive Behavior With Coupled Biodegradation and Fibrous Reinforcing Effects

ABSTRACTTo appropriately simulate the long‐term mechanical behavior of municipal solid waste (MSW), a constitutive model coupling the effects of biodegradation and fibrous reinforcement was developed. In the proposed model, the compressive deformation due to biodegradation was regarded as being caused by an additional equivalent stress. Considering the effect of biodegradation, an evolution equation of the equivalent stress was proposed, and a plastic volumetric strain hardening law was developed. A fibrous reinforcement parameter was introduced, which was associated with the fiber content, stress state, and plastic shear strain of MSW. A plastic shear strain hardening law was developed to model the fibrous reinforcement. Based on the associated flow rule and two plastic strain hardening laws, the proposed model was established. The proposed model well simulated the hardening properties of MSW, as evidenced by the stress‒strain curves and the consistent, nonlinear increase in volumetric strain with axial strain. The differences in the shear strength and volumetric deformation due to the confining stress and fiber content were also well simulated by the model. Furthermore, the model predictions accurately reflected the findings of experiments conducted over a period of 10 years. Finally, parametric investigations were used to calibrate this proposed model, which can well characterize the long‐term MSW mechanical behavior.

Hyperbolic Evolutionary Model for Equivalent Modulus of Sand and Characterization of Its Cyclic Hardening Properties

The cyclic hardening characteristics of soil hold significant importance for understanding its performance, and the evolution of the deformation modulus serves as a crucial indicator of the hardening properties. Deformations can be classified into elastic and plastic deformations and expressed in terms of modulus; however, their roles in the cyclic hardening process remain unclear. In this study, the elastic and plastic moduli were separated using the hyperbolic evolutionary model, which characterized the evolutionary properties of both to reflect the cyclic hardening process. A series of cyclic triaxial shear tests was conducted utilizing ISO sand and emery as test materials. A hyperbolic evolution model relating the equivalent modulus to the number of cycles was established, and the effect of various test conditions on the elastic modulus is discussed. The results indicate that: (1) the relationship between the equivalent modulus and the number of cycles is hyperbolic; and (2) the parameters k and b of the hyperbolic evolution model correspond to the elastic and plastic moduli, allowing for the separation of the evolution of both from that of the deformation modulus. The hyperbolic evolution model of the equivalent modulus proposed in this paper offers new insight into the cyclic hardening properties of sand.

Research on Mechanical Properties of High‐Manganese Steel Coating Manufactured by Coaxial Powder‐Feeding Laser Cladding

Due to the process complexity of the high‐carbon high‐manganese steel (HMnS) in casting and arc welding, this article propose the coaxial powder‐feeding laser cladding (LC) of HMnS coating using self‐developed HMnS powders. Firstly, high‐carbon HMnS coatings are prepared on the 16Mn substrate using coaxial powder‐feeding LC technology. It has a single austenite phase, without large defects such as pores and cracks. Then, ultrasonic shock peening is used to harden the HMnS coating, and the mechanical properties such as microhardness, impact toughness, wear and tensile properties are measured, which prove that HMnS coating has excellent working hardening, plasticity, toughness, and wear resistance properties. Finally, transmission electron microscopy is used to investigate the coupling effects such as dislocations, multiple twinning, and stacking faults on the HMnS coating after tensile fracture (true strain 39.2%). The deformation strengthening mechanism based on the dynamic Hall–Petch effect is revealed. The research results provide a new method for the preparation of high‐carbon HMnS coatings, and a new idea for expanding the application of high‐carbon HMnS.

Coal structure evaluation and morphological properties that affect the coal usage in industries

AbstractThe contemporary research article is central to understanding coal structure evaluation and the morphological development impacting its utilization in different applications. Through Mineral Liberation Analysis (MLA) designs high content phyllosilicates minerals and swelling clay minerals were rationalized to provides a novel insight into enhanced coal beneficiation and the benefits of coal by-product re-utilization progressions that encourage safer environments and economic sustainability. This work commences with collection of five (5) different coal samples from the central district region in Botswana, sample characterization deploying Thermogravimetric coal analysis (TGA), x-ray fluorescence spectroscopy (XRF), x-ray diffraction (XRD), scanning electron microscopy (SEM) and the Hardgrove Grindability Index (HGI) test that was directed to quantification of the coal hardness and fracture toughness during milling. The cumulative objective was to understand the correlation that exists between the natural composition of the coal sample and their adaptation and application in various carbonaceous products. A solid connection was thus identified in the sulfur and phosphorus weight percentage inclusions in all the coal materials hence higher significance in sphalerite mineral phases (Zn, Fe) S critically increased the fracture toughness and hardness properties. Moreover, mineral amalgams intrinsic to the coal maceral such as aluminum oxides (Al2O3), silicate (SiO2), calcites (CaO), Iron oxide (Fe2O3), potassium feldspars (K − AlSi3O8), albite (Na − AlSi3O8), and anorthite (Ca − Al2Si2O8) compounds in alkali feldspars were detected in larger quantities. The coal industry has attracted much industrial attention to manufacturing foundations producing cement, ceramic tiles, paving bricks, and material synthesis and will continue to supply other economic sectors in the conceivable future. Graphical Abstract

Effect of Co Addition on the Microstructure and Mechanical Properties of Sn-11Sb-6Cu Babbitt Alloy

A Babbitt alloy SnSb11Cu6 with 0–2.0 wt.% Co was synthesized using the induction melting process. This study examined the effect of cobalt (Co) on the microstructure, tensile properties, compressive properties, Brinell hardness, and wear properties of SnSb11Cu6 using optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), a universal tensile testing machine, a Brinell hardness tester, and a wear testing machine. The results indicate that the optimal quantity of Co can enhance the microstructure of the Babbitt alloy and promote microstructure uniformity, with presence of Co3Sn2 in the matrix. With the increase in Co content, the tensile and compressive strength of the Babbitt alloy first increased and then decreased, and the Brinell hardness gradually increased with the increase in Co content. The presence of trace Co has a minimal effect on the dry friction coefficient of the Babbitt alloy. When the Co content exceeds 1.5 wt.%, the friction properties of the Babbitt alloy deteriorate significantly. The optimized Babbitt alloy SnSb11Cu6-1.5Co was subsequently fabricated into wires, followed by conducting cold metal transfer (CMT) surfacing experiments. The Co element can promote the growth of interfacial compounds. The microstructure at the interface of the Babbitt alloy/steel is dense, and there is element diffusion between it. The metallurgical bonding is good, and there are serrated compounds relying on the diffusion layer to extend to the direction of the additive layer with serrated compounds extending and growing from the diffusion layer to the additive layer. Overall, Babbitt alloys such as SnSb11Cu6 exhibit improved comprehensive properties when containing 1.5 wt.% Co.

Mechanical and Structural Investigation of Zn-MnO<sub>2</sub> Coating on Mildsteel

Failure in manufacturing industries is a worldwide concern and it occurs most often at elevated temperatures and pressure. Acid, gases, and steam are known to be corrosion and stress-induced propagators resulting in incessant catastrophes. More so, material failure can be due to the substrate material used in the coating while substrate failure can further be classified into the substrate morphology, surface chemistry as well as contamination. Thus, the study developed a multifaceted layer of zinc barrier coating via the electrodeposition technique and observe its response by characterizing the developed coating. The mild steel plate, Zn and MnO2 were procured and characterized according to the ASTM standard. Mild steel of dimension 60×30×2 mm was sectioned and polished using varying sizes of abrasives. The result of the coating thickness showed that Zn-6MnO2 had a weight gain of 0.30g. Zn-12MnO2 was observed to have excellent corrosion performance compared to the as-received and the other formulations of Zn-MnO2 with a corrosion resistance of 2.117 mm/year. The SEM image of Zn-MnO2 showed aggregates of clustered grains, thus, no possible fracture lines were observed on the coating surface. Zn-12MnO2 exhibited a hardness value of 252.72 BHN. Additionally, the EDS of the coatings revealed significant elements that helped in the corrosion performance and hardness properties of the coatings. Keywords: Electrodeposition, Corrosion, Zinc barrier coating, Hardness value, EDS analysis

Effect of addition on microstructures and mechanical properties of cBN/Cu-Zn-Ti composites via the pulse electric current sintering

In order to improve the performance of metal-bonded grinding wheels, the cBN/Cu-Zn-Ti composites were fabricated by pulse current sintering with several different Co contents (i.e., 5, 10, and 15 wt%) were added. The specimen microstructure, interfacial analysis and fracture morphology of pulse current sintering cBN grain were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). The mechanical properties of hardness, wear resistance, and three-point bending strength of the fabricated specimens were tested. The electrochemical properties was also tested. The specimen shape fabricated by pulse current sintering using the composite Cu-Zn-Ti alloy doped by Co was better than pure Cu-Zn-Ti alloy. The microscopic analysis revealed that TiB2 and TiN were maintained between the Cu-Zn-Ti composites and cBN. With the addition of Co, the hardness, flexural strength and wear resistance of the specimens are improved. The new phase CoTi3 enhancing strength of the metal composite via the Orowan mechanism. The S5 specimen containing 15 wt% Co particles has the highest flexural strength, which is 485.83 MPa and satisfies the requirements of high speed grinding. Meanwhile, when the Co content reaches 10 %, the lowest friction coefficient (0.217) and lowest wear rate (0.81 mg) are achieved for the sample. With the addition of Co, the corrosion resistance of the material is significantly improved.

Mechanical and wear behavior of self-lubricating hybrid metal matrix composite(MMC)

This study investigates the mechanical and wear behavior of self-lubricating mixed metal matrix composites (MMCs) by focusing on magnesium reinforced with graphene nanoparticles (GNP) and silicon carbide (SiC). The aim of this study was to explore the potential of magnesium as a base material for advanced applications due to its lightweight and strength properties, while combining GNP for improved lubrication and SiC for increased mechanical strength. Samples were prepared and analyzed using powder metallurgy techniques and the results showed that while GNP improves self-lubrication, it reduces the strength of the material. However, the addition of SiC counteracts this effect and improves the hardness and overall mechanical properties of the composite. This study provides insights into the future development of lightweight, durable and self-lubricating materials for the automotive and aerospace industries.

Investigation of dynamic impact behavior of bighorn sheep horn

The horn of the bighorn sheep is composed of keratin-based biological material that has a tubule-lamella structure, which gives it anisotropic hardening properties under impact loading. This paper aims to investigate the energy dissipation mechanisms inherent in bighorn sheep horns by developing a numerical material model that accounts for the horn’s anisotropic features and strain-rate effects. To this end, a transversely isotropic constitutive model, which includes both anisotropic hardening and strain-rate effects, was formulated to accurately predict the mechanical behavior of bighorn sheep horns. Material characterization was conducted through uniaxial compression tests that were conducted under quasi-static and dynamic conditions. The developed constitutive model was implemented into LS-Dyna via a user-defined material subroutine and was validated against empirical data. The validated numerical model was used to investigate the horn’s mechanical responses under dynamic loading conditions. The paper focused on impact energy dissipation mechanisms, including energy absorption and transition, stress distribution, and displacement wave propagation. The insights gained from this paper are expected to significantly contribute to the development of novel artificial materials with enhanced energy absorption and impact mitigation properties.

Characterization of Heat-treated Bearing Rings via Measurement of Electromagnetic Properties for Pulsed Eddy Current Evaluation

Nondestructive evaluation of heat-treated bearing rings is a critical technique for quality control in industries. However, there are few reports addressing the complex mapping between hardness and electromagnetic properties due to the intricate changes in the microstructure. This paper proposes a dual-method approach, combining magnetic saturation eddy current techniques and Barkhausen noise reconstruction hysteresis loop techniques, to independently establish the relationship between hardness and electromagnetic properties. The results show that the electrical properties of unqualified specimens are significantly higher than those of other specimens, with qualified specimens have slightly higher properties than untreated ones. Additionally, an inverse relationship between hardness and magnetic properties is observed. Based on the obtained electromagnetic parameters, a pulsed eddy current hardness detection simulation model is established, which has the potential to improve purely data-driven methods for hardness detection in deep learning.

Hardening properties, water resistance and associated micro-mechanism of nano-modified calcium sulphoaluminate cement

Calcium sulphoaluminate cement (CSA) is considered a sustainable alternative to traditional Portland cement to reduce CO2 emissions. To further improve the hardening properties and water resistance of CSA and advance its extensive special engineering application, nanoparticles including nano-SiO2 (NS), nano-MgO (NM) and nano-Al2O3 (NA) were used as nano-modifiers for CSA. The effects of nanoparticles dosage on the setting time, compressive strength and water resistance of nano-modified CSA were experimentally evaluated, and the micro-mechanisms were also clarified by conducting X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TG) tests. The results showed that incorporating nanoparticles into CSA obviously shortened the initial and final setting times. The appropriate addition of nanoparticles effectively enhanced the compressive strength of CSA, and the optimum dosages of NS, NM, and NA were respectively determined to be 0.5%, 1.0%, and 0.5%. Water immersion decreased the bonding strength of CSA, and adding nanoparticles can effectively weaken this water-induced deterioration effect. Under water immersion environment, the optimum dosages of nanoparticles would be increased to obtain the highest residual water immersion strength and minimum strength loss rate. The generation of ettringite was mainly responsible for the compressive strength and water resistance improvements of nano-modified CSA. The hydration process of nano-modified CSA was clarified and the corresponding micro-mechanism model was proposed. Furthermore, the benefits and challenges of using nano-modified CSA were also analyzed, advancing its widespread application in rapid repair of special engineering.

Hardness properties of calcium and magnesium ions in drinking water

The drinking water parameter - water hardness - is defined as the sum of calcium and magnesium ion concentrations. In this study, their precipitation during boiling was investigated, using water of different hardnesses, calcium to magnesium ratios, natural tap and bottled waters. During boiling, pH value, conductivity, and calcium and magnesium concentrations were measured. Further, the morphology and composition of precipitates were analyzed. Boiling tests with durations of 30 min showed only a decrease of calcium concentration by precipitation. Longer boiling of water with a high proportion of magnesium showed decreasing magnesium concentrations once the calcium precipitation was completed. Calcium carbonate precipitated as calcite and aragonite crystals with aragonite needles occurring in the presence of high magnesium concentrations. Magnesium hydroxide formed during precipitation was identified as hydromagnesite crystals with different crystallization morphologies. Unexpectedly, for a water with low and equimolar concentrations of calcium and magnesium only magnesium precipitated at the relatively low pH 8.7. In summary, calcium ions in drinking water are evaluated as being of considerably higher relevance for the hardness properties than the magnesium ions. However, the precipitation of both minerals depends on their concentrations and ratio as well as on the pH value and the water matrix.

Utilization of spent graphite from lithium-ion batteries waste as sustainable reinforcing filler for thermal, vibration-damping, and noise control applications

This study explores the practical application of using spent graphite (SG) derived from lithium-ion battery waste as a sustainable reinforcing filler for fabricating rubber composites. Two types of rubber, natural rubber (NR) and butyl rubber (BR), were employed as matrices, and eight composites were fabricated by increasing SG loadings [0, 10, 20, and 30 parts per hundred rubber (phr)]. The effects of these SG loadings on the composites' morphological, physical, thermal, wettability, mechanical, dynamic mechanical, vibration-damping, and acoustic properties were thoroughly investigated. The findings demonstrate significant improvements with increasing SG loading, particularly in the BR/SG30 composite. By reinforcing 30 phr of SG into the BR matrix, the density, hardness, thermal degradation, and sound-insulating properties improved by approximately 3.50%, 15.64%, 6.05%, and 5%, respectively, compared to the NR/SG0 composite. The damping ratio (ξ) of MSBB + BR/SG30 was approximately 18.04 at the second vibration mode, and the overall sound power level of MSBB was reduced by about 12.20 dB(A) when the BR/SG30 composite layer was applied, highlighting its potential for real-world vibration and noise control applications. These results underscore the significant role of SG as a sustainable reinforcing filler in enhancing the properties of rubber composites, particularly in the BR matrix, making it a promising option for applications requiring effective vibration and noise control. This research opens new possibilities for using SG in various engineering applications, inspiring further exploration and innovation.

Thermophysical properties of AlxCoCrCuFeNi high entropy alloys

The AlxCoCrCuFeNi (x = 0.25, 0.5, 1, 2) high entropy alloys (HEAs) were prepared by arc melting and spray casting techniques. Their microstructures, hardness, and thermophysical properties such as fusion enthalpy, entropy, thermal diffusion coefficients, thermal expansion coefficients, were investigated. XRD results indicated that AlxCoCrCuFeNi (x = 0.25 and 0.5) alloys were composed of a high-entropy FCC phase and Cu-rich nanophase. As the Al content increased to 1 and 2, the phase structures included the AlNi-rich B2 phase, FeCr-rich A2 phase and Cu-rich nanophase. With the increased Al content, the microstructures of AlxCoCrCuFeNi HEAs transitioned from coarse dendrites to petal-like dendrites, and the grains were continuously refined. Moreover, the Al additions reduced the density whereas increased the Vickers hardness of the alloys. The maximum hardness observed in Al2CoCrCuFeNi HEA was approximately 2.4 times greater than that of the Al0.25CoCrCuFeNi HEA. The thermal diffusion coefficients of alloys initially increased and subsequently decreased as the temperature elevated. The phase transformation induced by Al content was an effective method for rapidly homogenizing the internal temperature of alloys. Furthermore, the crystal structure, elemental segregation, lattice distortion, enthalpy and entropy of fusion, and lattice vibration frequency all mutually affected the thermal diffusion and expansion coefficients of AlxCoCrCuFeNi HEAs.

Ecofriendly hybrid natural fiber reinforced polypropylene composites from biowastes

The used ground coffee waste (GCW) and tea leaf waste (TLW), the large wastes from the beverage process, were selected as natural reinforcement and natural pigment in the polypropylene (PP) matrix. In this work, the maleic anhydride polypropylene (MAPP) was added to the composites to develop the compatibility between fillers, fibers, and polymer matrix. The TLW/PP composites, GCW/PP composites, and GCW/TLW/PP hybrid composites were prepared in the ratio of TLW and GCW ranging from 0 to 30 wt% with the addition of MAPP at 5 wt% of fillers. The presence of GCW and TLW in the PP matrix decreased tensile properties and impact resistance but increased flexural modulus and hardness of PP at high concentrations of GCW and TLW. The increase in GCW and TLW concentration slightly reduced melting temperature but it enhanced the tensile and flexural modulus. Furthermore, it enhanced the hardness, thermal and rheological properties of the composites. The TLW/PP composites had better mechanical properties, and rheological properties than GCW/PP composites but thermal properties were quite similar. The mechanical properties of GCW/TLW/PP hybrid composites were better than those of GCW/PP composites but lower than those of TLW/PP composites. The rheological and thermal behaviour of hybrid composites were like that of TLW/PP composites. Incorporating MAPP improves the mechanical and rheological behavior of PP composites by enhancing the interaction among PP, GCW, and TLW. However, this addition does not significantly enhance the composites’ thermal properties. The optimum composite was hybrid composites of GCW/TLW/PP consisting of GCW of 10 wt%, TLW of 20 wt%, and MAPP of 1.5 wt% which presented good mechanical, thermal, and rheological properties. The mechanical properties of this hybrid composites were as follows: a tensile strength of 26.35 MPa, elongation at break of 10.91%, tensile modulus of 636.69 MPa, flexural strength of 45.57 MPa, flexural modulus of 3632.86 MPa, impact resistance of 12.72 kJ/m2, and a Shore D hardness of 76.15. The overall results showed that GCW and TLW can be used as reinforcement material and natural pigment in the polymer matrix.

Optimized strategy for induction cladding of diamond/Ni-based wear-resistant coatings

Diamond/Ni-based wear-resistant coatings were fabricated on 45 steel using induction cladding, followed by laser remelting of the gradient coatings. The microstructure, phase composition, hardness, and friction properties of the coatings were examined. Results revealed that the surfaces of the composite and gradient coatings primarily consisted of a hard γ-Ni matrix and phases such as diamond, Cr7C3, and Cr23C6. High-temperature diffusion results in a strong metallurgical bond between the coating and the substrate. The gradient coating design significantly reduce the physical property mismatch between the 45 steel substrate and the composite coating. While laser remelting increased chromium aggregation and achieved a more uniform distribution of Fe, Ni, and Si. XRD analysis indicated that the Ni2Si diffraction peaks disappeared. Concurrently, the surface roughness and wear loss of the coating decreased, while the microhardness of the surface layer increased to 1030.74 HV, enhancing surface wear and corrosion resistance performance.

Nanostructured silver vanadate gel: Evaluation of physicochemical, mechanical, and antibiofilm properties against a five-species oral model

The aim of this study was to develop a gel with nanostructured silver vanadate decorated with silver nanoparticles (β-AgVO3) and to evaluate its physicochemical, mechanical, and antibiofilm properties against a five-species oral model composed of Candida albicans, Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, and Pseudomonas aeruginosa. The formulations were prepared with 0 % w/v (G0), 0.02 % w/v (G1), 0.05 % w/v (G2), and 0.12 % w/v (G3) β-AgVO3. The physicochemical properties of pH (n = 5), viscosity (n = 5), spreadability (n = 10) and syringability (n = 10) were evaluated, as well as the mechanical properties of hardness, cohesiveness, compressibility, elasticity, and adhesiveness using the texture profile assay (TPA) (n = 5) and ex vivo mucoadhesion (n = 5). The antibiofilm effect was assessed by counting colony-forming units (CFU/mL) (n = 8), metabolic activity (XTT) (n = 8), and scanning electron microscopy (SEM) (n = 1), using 0.12 % chlorhexidine gel (CG) as a positive control and G0 as a negative control. All groups demonstrated a neutral pH. G2 and G3 exhibited reduced viscosity and syringeability, along with increased spreadability. The incorporation of β-AgVO3 did not impact the gel's elasticity or cohesiveness but led to a decrease in hardness, compressibility, and adhesiveness. Ex vivo mucoadhesion was not altered by the addition of the nanomaterial. G3 showed a higher microbial reduction compared to GC and G0. It was concluded that the formulations with β-AgVO3 showed compatible physicochemical and mechanical properties for application and maintenance in the oral cavity. G3 showed superior antimicrobial effect against all microorganisms compared to GC and G0.

Reinforcement of Epoxidized Natural Rubber with High Antimicrobial Resistance Using Water Hyacinth Fibers and Chlorhexidine Gluconate.

In this study, epoxidized natural rubber (ENR) was mixed using a two-roller mixer. Water hyacinth fiber (WHF) acted as a reinforcing agent in the preparation of the rubber composite at 10 phr (ENRC/WHF). Chlorhexidine gluconate (CHG) was added at different concentrations (1, 5, 10, and 20 phr) as an antimicrobial and coupling agent. The tensile strength increased with a CHG content of 1 phr (4.59 MPa). The ENRC/WHF/CHG20 blend offered high hardness (38) and good morphology owing to the reduction in cavities and fiber pull-out from the rubber matrix. The swelling of the sample blends in oil and toluene decreased as the CHG content increased. Reactions of -NH2/epoxy groups and -NH2/-OH groups occurred during the preparation of the ENRC/WHF/CHG blend. The FTIR spectroscopy peak at 1730 cm-1 confirmed the reaction between the -NH2 groups of CHG and epoxy groups of ENR. The ENRC/WHF/CHG blend at 10 phr and 20 phr exhibited zones of inhibition against three bacterial species (Staphylococcus aureus, Escherichia coli, and Bacillus cereus). CHG simultaneously acted as a crosslinking agent between ENR and WHF and as an antimicrobial additive for the blends. CHG also improved the tensile strength, hardness, swelling, and antimicrobial properties of ENR composites.

Experimental study on the heat input behavior of wire-arc additively manufactured 316L stainless steel parts for repairing applications

Wire arc additive manufacturing (WAAM) as an emerging manufacturing technique for fabricating large size metallic components with a higher deposition rate and lower material wastage. In this research, a thin walled-part was fabricated from stainless steel 316L with various heat input (HI) (low heat deposited wall (LHDW) and high heat deposited wall (HHDW) using the cold metal transfer (CMT)-based WAAM process. The microstructure characteristics, metallurgical characterization, and mechanical properties of the WAAM manufactured thin-walled component were examined. The deposited wall measuring 120 mm in length and 50 mm in height was fabricated by WAAM using ER316L wire and CMT. Microstructure of the deposit parts consists of the equiaxed, coarse, and columnar grains with epitaxial growth of dendrites were formed. The decrease in HI leads to the improvement of material hardness, yield and ultimate tensile strength (UTS) as well as the percentage elongation after fracture of the material decreases. EBSD analysis demonstrates the average grain size of 0.98 µm in LHDW and 2.43 in HHDW respectively. XRD results shows that main crystal structure found in WAAM thin-walled sample was γ-austenite phases. The microhardness distribution of the fabricated component exhibited the stability characteristics with the average value ranging between 213–237 HV. The tensile studies demonstrate the UTS of the LHDW and HHDW along the horizontal direction are 477 MPa greater than the vertical direction of 468 MPa and observed the anisotropy properties. The fractured surface was characterized by the emergence of obvious dimples revealing the ductile fracture. The lower HI and finer solidification structure of component fabricated by LHDW has greater tensile and hardness properties than that of HHDW. This study presents the initial assessment results for repairing stainless steel components subjected to mechanical damage.

Effect of Alumina as Reinforcement on the Mechanical and Physical Properties of Recycled AA6061 Aluminium

The utilisation of reinforcement materials in aluminium metal matrix composites is widely used in the manufacturing sector due to their lightweight nature, excellent strength-to-weight ratio, enhanced fracture toughness, and improved mechanical properties. The purpose of this study is to investigate the effect of reinforcing alumina in recycled AA6061 aluminium on the properties of the resulting aluminium matrix composite. Various compositions of recycled AA6061 aluminium reinforced with alumina were prepared and analysed using the cold compaction method. The results show that the addition of alumina composition increases the hardness properties of the composite by up to 5 wt.% at 32.91 Hv compared to the unreinforced sample at 30.63 Hv, but the hardness decreases as the alumina mass composition increases. According to the analysis of physical properties, in comparison to the unreinforced sample, the density decreases with increasing mass composition of alumina up to 10 wt.%, which is from 2.4636 g/cm3 to 2.3014 g/cm3, respectively. In relation to the microstructure of the samples, the addition of alumina results in irregular shapes with larger pores. An increasing in the mass composition of alumina results in increased porosity and water absorption.