Materials and Technology

MODELING OF THE CUTTING FORCES IN END MILLING OF A METALLIC MULTILAYER MATERIAL

Uroš Župerl, Miha Kovačič — Mon, 19 Aug 2024 11:52:23 +0200

Multilayer metal materials are increasingly used by tool shops in the production of transfer tools for sheet-metal forming. In research, it is found that during the machining of these advanced materials, damage to the cutting edge often occurs due to jumps in the cutting forces. The size of the cutting forces when milling a multi-directionally layered metal material is influenced by both the direction of depositing the individual layer and the geometry of the cutting tool. The main goal of the research was to create a mechanistic model of cutting forces for the end-milling of unidirectional and multidirectional 20MnCr5/316L four-layered metal material. The results of the model were compared with experimental data, where a good agreement was found when milling unidirectional layered material and a slightly worse agreement when milling multidirectional material. The maximum observed deviation of the predicted cutting forces is 14.6 % for all the comparative tests.

MICROSTRUCTURE AND PROPERTIES OF 6082/7075 MAGNETIC-FIELD-ASSISTED RESISTANCE-SPOT-WELDED JOINTS

Xiaoou Zhu, Zhanqi Liu, Guili Yin, Yu Li — Mon, 19 Aug 2024 11:59:17 +0200

To advance automotive lightweighting, a study was conducted on steady-state magnetic-field-assisted resistance spot welding of 6082 aluminum alloy (1.0 mm thick) and 7075 aluminum alloy (1.5 mm thick) with thermal compensation. The influence of varying magnetic induction intensity on the microstructure and tensile properties of welded joints was assessed under the same welding current, time and electrode pressure. The results revealed that the Lorentz force induced by magnetic induction intensity ranging from 0 mT to 60 mT could promote an outward circumferential movement of molten metal within the weld nugget. This movement, at the same time, led to an increase in the weld-nugget size and improved the efficiency of thermal resistance. At a magnetic induction intensity of 80 mT, no weld-nugget formation occurred in the welded joint. Microstructural observations at magnetic induction intensities of 0 mT and 60 mT revealed equiaxed grains at the nugget center and columnar dendrite grains at the nugget edge in the welded joints. The Lorentz force accelerated the weld cooling rates after the addition of magnetic field, refining the weld grain structure. Tensile properties of the welded joints gradually improved with increasing the magnetic induction intensity from 0 mT to 60 mT, driven by the weld nugget size expansion and weld grain refinement. Overall, the present study indicated that the magnetic induction intensity of 60 mT resulted in the most favorable comprehensive mechanical properties of the investigated welded joints.

WEAR MECHANISM FOR DEEP-WELLS DRILLING TOOLS

Jurij Šporin, Željko Vukelić — Mon, 19 Aug 2024 12:03:49 +0200

When drilling deep wells with a large diameter drill bit, it is important to ensure optimum progress with the cutting tool, effectively cutting or crushing the rock through which we are penetrating for as long as possible. When drilling a well, we encounter complex conditions at depth resulting from variables such as the strength of the rock, the load on the bit, the number of revolutions of the tool, significant temperature and pressure fluctuations and the material properties of the tools used in the drilling. The article shows how mechanisms develop due to the drilling parameters used and the complex drilling conditions, which lead to wear of the cutting unit and a decrease in efficiency. The influence of the aforementioned drilling conditions on the steel materials of the roller-cone drill bit, which is the tool we use to penetrate deeper, is reflected in the change in the material properties of the steels. These changes, which are explained in the article, lead to gradual fatigue and degradation of the materials. The wear mechanism of the cutting tool is composed of the different material properties of the steel from which the roller-cone drill bit is formed, the influence of sudden temperature changes on the steel materials and erosion processes on free, newly formed surfaces, which are the result of the erosion effect.

SYNTHESES AND CHARACTERISTICS OF CALCIUM-BASED GEOPOLYMER FROM SOLAR-CELL PANEL-GLASS WASTE BY HYDROTHERMAL METHOD

Hoc Thang Nguyen, Quang Binh Nguyen, Van Phuc Nguyen, Trung Kien Pham — Mon, 19 Aug 2024 12:19:43 +0200

A calcium-based geopolymer was synthesized using a blend of recycled glass powder from solar panels (PV glass waste), limestone, and a sodium silicate solution, which underwent hydrothermal autoclaving at 180 °C for varying durations. This material is regarded as environmentally friendly and has garnered research attention worldwide. In this investigation, limestone served as the calcium source, while recycled glass from solar panels provided the SiO₂ necessary for producing calcium-based geopolymer materials. Currently, solar-panel waste poses a significant environmental challenge that requires attention. The objective of this research was to develop a sustainable and high-performance calcium-based geopolymer using waste materials, specifically recycled glass from solar panels and limestone. The study aimed to evaluate the effects of hydrothermal autoclaving on the compressive strength, volume weight, porosity, and water absorption of the synthesized geopolymer, as well as to understand the microstructural transformations involved. The results revealed a remarkable 430 % increase in the compressive strength of the specimens following hydrothermal autoclaving for 24 to 96 hours compared to the unautoclaved samples. Concurrently, the volumetric weight had a substantial rise from 1.54 % to 2.31 g/cm³, with corresponding decreases in the porosity and water absorption from 38.1 % to 16.9 % and 10.26 % to 5.08 %, respectively. An X-ray diffraction (XRD) analysis of the mineral composition and a scanning electron microscope (SEM) examination of the microstructure demonstrated a transformation of all samples from an amorphous gel structure to needle- or spike-shaped fibrous, and then sheet-like CSH structures. These new structures exhibited dimensions of less than 10 µm in length, less than 2 µm in width, and less than 400 nm in thickness. The resulting CSH products constitute calcium silicate hydrate minerals, characteristic of calcium silicate materials, which are synthetic products arising from chemical reactions among SiO₂, CaO, and H₂O under hydrothermal conditions. This study underscores the potential of using recycled materials to produced high-strength geopolymers, offering a promising solution to the environmental challenge of solar-panel waste.

COMPARATIVE STUDIES ON MICROSTRUCTURE AND TOUGHNESS OF 9 % Ni STEEL JOINTS WELDED BY SMAW AND GTAW

Haiyang Zhu, Xuebing Yang, Kun Liu, Xiaoyong Wang, Yuhang Du, Jiasheng Zou — Mon, 19 Aug 2024 12:45:49 +0200

The microstructure and impact toughness of 9 % Ni steel joints welded by shielded metal arc welding (SMAW) and gas tungsten arc welding (GTAW) were investigated. The two kinds of weld metal were mainly composed of cellular dendrites and a granular precipitated phase. The grains and cellular dendrites of the GTAW weld metal were smaller than those of the SMAW weld metal. The precipitates in the SMAW weld metal were stripe-shaped while those in the GTAW weld metal were rod-shaped; the number of precipitates in the GTAW weld metal was lower than in the SMAW weld metal. The low-temperature impact toughness of the GTAW weld metal was better than that of the SMAW weld melt.

4-TERT-BUTYLBENZOIC ACID-INCORPORATED POLYSTYRENE: AN EFFECTIVE CATION-EXCHANGE POLYMER MATRIX FOR THE REMOVAL OF METAL IONS FROM TANNERY EFFLUENT

Mon, 19 Aug 2024 12:54:20 +0200

The preparation of a 4-tert-butylbenzoic acid-incorporated polystyrene matrix as the polymer matrix for removing the metal ions present in water is reported. The hydrophobic interaction between the polystyrene and the tert-butyl group of carboxylic acid was exploited to bind the carboxylic acid on polystyrene. Thus prepared polymer matrix was investigated for its ability to exchange and remove metal ions from water. Better efficiency was obtained with different metal ions, including copper, iron, calcium, magnesium, chromium (III), etc., during a batch process as well as a continuous process. The carboxylic acid was not leached out during the process and the hydrophobic force was strong enough to avoid leaching out. Further, it was employed to remove metal ions, particularly chromium, from tannery effluent.

HYDROTHERMALLY DEVELOPED TITANIUM DIOXIDE AND EUROPIUM-DOPED COMPOSITE MATERIALS FOR PHOTODEGRADATION APPLICATIONS

Sasikanth S. M., Ganapathi Raman — Mon, 19 Aug 2024 12:58:09 +0200

Metal oxide nanocomposites are a critical element in nanoscale technology. Because of their many uses, a great deal of study has involved photocatalytic materials. These photocatalytic degradation characteristics also included applications like solar-cell applications. Wastewater management was included in the photodegradation property. The following study explored the development of europium tungstate nanocomposites with titanium dioxide and how they can be used in photocatalytic applications. The synthesis was conducted using the hydrothermal method and is characterized by Fourier-transform infrared spectroscopy, X-ray diffraction spectroscopy, scanning electron microscopy, and energy-dispersive spectroscopy. Application experiments were conducted using four distinct dyes, namely methyl orange, methylene blue, congo red and methyl red. The photodegradation experiments were conducted using visible light emitted by a tungsten-filament lamp. Methylene blue and methyl orange degraded to 20 % and 35 % after 1 hour respectively. After 90 min, the degradation of methylene blue went down to 15 % and congo red degraded down to 9 %. With the experiment conducted, the sample showed that it had a relatively higher photodegradation property with the dyes used. The results show that the compound had better reaction with these dyes, with a degradation down to 10 %.

EFFECTS OF HOT-ROLLING PROCESSES ON THE FRACTURE BEHAVIORS AND MECHANICAL PROPERTIES OF 2009Al/SiCp METAL MATRIX COMPOSITES

Ze Wang, Zhiwen Liang, Qingxue Huang, Zixuan Li, Xiaomiao Niu — Mon, 19 Aug 2024 13:52:38 +0200

Defects such as pores and weak interfacial bonding in SiC-reinforced aluminum-matrix composites (AMCs) limit the reinforcement effect. The objective of this study is to control the microstructural defects and status of the Al/SiC interface in an 2009Al/SiCp composite using rolling processes. The influence of the rolling reduction rate on the microstructure and mechanical properties is investigated. The fracture behavior of the 2009Al/SiCp composite is observed through in-situ scanning-electron-microscopy tensile tests. The results demonstrate that an appropriate rolling reduction rate can effectively eliminate microstructural defects in the matrix and enhance the interfacial bonding strength of Al/SiC. Plastic deformation during the rolling processes expands the dislocation-strengthening regions near the Al/SiC interface. Consequently, mechanical loads can be more efficiently transferred from the aluminum matrices to SiC particles. In the as-sintered specimens, cracks primarily initiate at the Al/SiC interfaces during tensile tests. In contrast, cracks predominantly propagate from the SiC particles to Al matrices in the as-rolled specimens. This work provides a fundamental understanding of the dynamic changes in the microstructure and the resulting mechanical properties during hot rolling of SiC-reinforced AMCs.

INVESTIGATION INTO THE THERMAL DEFORMATION BEHAVIOR AND THE ESTABLISHMENT OF A CONSTITUTIVE RELATIONSHIP FOR Mn-Cr-Ni-Mo STEEL

Wei Liu, Hongchao Ji, Weimin Yin, Yubin Chen, Zhiru Dou, Xiaoli Yu — Mon, 19 Aug 2024 14:00:04 +0200

Isothermal compression tests were conducted on Mn-Cr-Ni-Mo steel at temperatures ranging from 1173 K to 1473 K and strain rates from 0.01 s^–1 to 10 s^–1 using a Gleeble-3800 thermal simulation tester. Four constitutive models for Mn-Cr-Ni-Mo steel, namely the Arrhenius model, Fields-Backofen model (F-B), original Johnson-Cook model (J-C), and the improved Johnson-Cook model (mJ-C) were established. A correlation coefficient (R) and the average absolute relative error (AARE) were employed to evaluate the predictive capability of these four models. Among them, the Arrhenius model exhibited superior accuracy in predicting the behavior of Mn-Cr-Ni-Mo steel. It and the isothermal thermal compression finite-element model were imported into Deform-3D software for a numerical simulation, aiming to analyze the distribution law of the equivalent stress field. A comparison was made between the time-stress data obtained from numerical simulation under different conditions and that from the isothermal compression tests. The results demonstrate good agreement between the time-stress curves of the numerical simulation and the experimental measurements, indicating that the established Arrhenius model can effectively simulate the thermal deformation of Mn-Cr-Ni-Mo steel. These research findings provide valuable fundamental data for simulating the plastic-deformation process of Mn-Cr-Ni-Mo steel.

THE EFFECT OF A Cr-FREE FINGERPRINT-RESISTANT PASSIVATION FILM ON THE PERFORMANCE OF HOT-DIP 55 % Al-Zn COATED STEEL

Mon, 19 Aug 2024 14:10:56 +0200

Cr-free fingerprint-resistant hot-dip 55 w/% Al-Zn coated steel (CFAZCS) is a upmarket steel plate product that is widely used in consumer goods with high added value, such as LCD back panels for monitors, as well as various electrical and electronic products. Passivation is a crucial process in the production of CFAZCS, greatly affecting the overall performance of the CFAZCS product. A comprehensive evaluation of passivation films from different manufacturers on the performance of CFAZCS can assist production enterprises in optimizing and controlling the product quality according to the requirements of target customers. This article comprehensively tests and evaluates the performance of corrosion resistance, acid/alkali resistance, anti-yellowing/blackening, paint adhesion, abrasion resistance, fingerprint resistance, and the conductivity of mainstream, commercially available, Cr-free, fingerprint-resistant, passivation solutions, providing guidance for the selection of passivation solutions in production processes.

INVESTIGATION OF THE MECHANICAL AND TRIBOLOGICAL BEHAVIOURS OF CUPOLA SLAG AND MWCNT-REINFORCED EPOXY HYBRID NANOCOMPOSITES: A SUSTAINABLE APPROACH FOR ENVIRONMENTAL PRESERVATION

Rajeswaran M., Prathap P., Kannan S., Sundaravadivel T. A. — Mon, 19 Aug 2024 14:16:41 +0200

This experimental investigation explores the mechanical and tribological characteristics of cupola slag (CS) and multiwall carbon nanotubes (MWCNTs) reinforced hybrid nanofiller epoxy composites. Cupola slag is an industrial by-product that is generated during the melting of cast iron. The disposal of slag residues in landfills results in environmental pollution. In the context of environmental preserving as well developing new engineering composites material from waste to resource. MWCNTs possess an excellent strength-to-weight ratio, high stiffness, and thermal properties. The mechanical and tribological characteristics of the hybrid nanocomposites comprising epoxy were examined by varying the weight fraction of fillers composed of CS and MWCNTs. The experimental results indicated that the ECSM3 hybrid nanocomposites have superior tensile strength and the flexural modulus improved by 92 % and 78 % respectively when compared with epoxy. Similarly, the tribology performance of the ECSM3 exhibited improved specific wear resistance of 97 %, 106 % and 88 % on the dry-sliding loads of 10 N, 20 N and 30N, respectively. A morphological analysis was carried out on fractured and worn surfaces of the specimen to understand the homogeneous dispersion and matrix-interlocking mechanism between the hybrid nanofillers and the epoxy matrix. The integration of CS alongside MWCNTs for the fabrication of epoxy hybrid nanocomposites represents a stride towards sustainable and eco-friendly technology in the production of multifunctional composite materials for diverse engineering applications.

LASER SURFACE TEXTURING TO IMPROVE THE TRIBOLOGICAL PROPERTIES OF Ti ALLOYS

Marjetka Conradi — Mon, 19 Aug 2024 14:21:16 +0200

Friction and wear requirements in the aerospace/space industry or in biomedical applications are governed by life-limiting challenges: the wide range of contact stresses and sliding speeds in movable parts and operating conditions such as extreme temperature changes, humidity and abrasive wear caused by electrostatically attracted dust. Surface modification by laser texturing has been introduced to adjust the surface characteristics of the base material to overcome its tribological limitations of use via different surface topographies, allowing for the ability of lubricant retention. Laser surface texturing is therefore effective in enhancing the tribological performance of materials via controllable surface topographies acting as traps for wear debris and lubricant reservoirs, leading to reduced abrasion. This paper reviews the tribological behaviour of a laser-textured Ti6Al4V alloy with different textures: lines, crosshatch and dimples. The fiction and wear characteristics for dry sliding are discussed and compared.

TRIBOLOGICAL AND MECHANICAL CHARACTERIZATION OF AL6060/SI3N4/BN HYBRID ALUMINIUM METAL MATRIX COMPOSITES

Jai Rajesh Pandurengan, Balambica Venkatesan, Achudhan Munuswamy — Mon, 19 Aug 2024 14:34:00 +0200

In recent years, aluminium-based composites have emerged as preferable substitutes for conventional aluminium alloys in various contemporary applications, like the aerospace and automotive industries. This shift can be attributed to their enhanced characteristics and superior properties. Improved strength-to-weight ratio, reduced thermal expansion, and superior wear resistance are just a few of the benefits. Several researchers have created aluminium metal matrix composites (AMMCs) by combining various ceramic reinforcing elements with aluminium alloys. Ceramic reinforcing materials increase the strength, hardness, and wear resistance. The aim was to enhance the mechanical and wear characteristics of a composite material, i.e., to find the mechanical characteristics of an Al6060/BN hybrid alloy, such as tensile strength, impact, hardness, etc. The composites were developed by incorporating silicon nitride (Si₃N₄), a hard ceramic material, as the main reinforcing component, along with boron nitride (BN), a solid lubricant, as the secondary reinforcement. The stir-casting technique was employed to fabricate aluminium metal matrix composites with varying weight fractions (0, 5, and 10) w/% of Si₃N₄ and BN. Tensile and hardness tests were conducted to analyse the basic mechanical properties of the resulting composites.