Key Engineering Materials Vol. 946

Abstract: This study examines the influence of tool eccentricity pin positioning on AA6061 aluminium alloy friction stir welds. A laser scanning confocal microscope and optical microscope was used to analyze the surface roughness and the cross-sectional microstructure of the samples. Surface roughness analysis reveal the thread-to-flat (T2F) samples show rougher surface with increasing rotational speed up to 1400 rpm. On the other hand, the surface appearance of flat-to-thread (F2T) samples show minimal change. Cross-sectional microstructural observations show that the stir zone area of both groups increases with increasing rotational speed. However, the periodic bands in T2F and F2T samples increases in the upper region and lower region of the stir zone, respectively.

Abstract: Three-dimensional finite element modeling (FEM) has been carried out using QForm software on the hot forging operation of the upper ball joint, involving the process of roughing and finishing. The material used is SNCM8 commercial alloy steel. This paper aims to optimize the initial billet size to achieve a final forged product without any defects. To accomplish this task, it was necessary to determine the initial optimum billet size by calculating the mass ratio. It is more practical to reduce the length of the initial billet and keep the diameter constant. The initial billet size was obtained by FE simulation by varying the five cases of mass ratio. The minimum dimension of the initial billet, which filled the die cavity without defects, was selected for the tryout experiments. The experimental results supported the FEM results and indicated that the optimum size was ∅48x152.88 mm, which may reduce material waste by 17.65%. Additionally, the forging load during the forging process was investigated. The actual forging load was slightly higher than the experimental one. The forging load showed a maximum error about 10.13%. Finite element simulation by QForm V10.1.6. software is recommended as an efficient tool for predicting the hot deformation behavior of the material during several stages of hot forging, which can save material costs and the cost of trials, leading to enhancements in the manufacturing process.

Abstract: This research aims to identify the optimal condition of the zinc Zamak3 alloys' melting process using 2k full factorial design and its optimizer in Minitab 18 software. The evaluation results of the ANOVA test with a first-order model revealed that the change in both independent variables simultaneously resulted in a statistically significant alteration of the percentage of slag. The independent parameters also had an effect individually on the response. Additionally, the slag percentage reduction was increased significantly due to an elevation of the temperature. However, the change of flux type resulted in an overall alteration of the slag percentage more than the change of melting temperature. The response optimizer demonstrated that the optimal condition was the melting temperature of 500°C coupled with the ZinCrex EP7119 flux achieving the lowest slag percentage of 1.672%, with the 95% confidence interval ranging from 0.643% to 2.701%.

Abstract: Single point incremental forming process, which is also known as SPIF, that forms from one direction. SPIF process was used for milling an aluminum metallic sheet. In this paper, an aluminum (A5052) sheet was formed in a conical shape by the SPIF process. The A5052 sheet was deformed by the computer numerical control (CNC) technology in the T60 series milling machine. The conical shape was deformed by the spiral toolpath in the T60 series milling machine. At the surface of the A5052, lubricant grease was continuously applied manually for reducing the friction generated due to milling. Also, for decreasing the tool rotational force friction on the A5052 sheet there was the use of lubricant. Moreover, 0.1mm step-down is used for the tool path because it takes more time for forming a metallic sheet, however, it deformed the sheet smoothly. The 0.5mm step-down g-code was extracted from fusion 360. Then the metallic sheet A5052 surface was compared before and after deformation. For testing a metallic sheet A5052 the formability parameter was analyzed in the experiment part. The experiment was performed to find the optimal smooth surface from the CNC milling machine. The initial roughness value and the microscopic image were presented in the investigational part. Likewise, the comparison of points for the highest and lowest rough point was further discussed and compared throughout the experiment.

Abstract: Conventional finite element (FE) modelling, which employed structured mesh, is unable to simulate local damage evolution at microstructure level. This paper aims to investigate the creep rupture and damage behaviour of Grade 92 steel under a creep environment using microstructural-type FE mesh. The idealised microstructures of the material were generated based on the Voronoi tessellation technique. Three notched bar specimens with different notch acuities were modelled in Abaqus v6.13 software and a ductility exhaustion based damage model was employed to estimate the damage state. The influence of the notch constraint on the ductility is accounted for in the simulation. It is found that the results obtained from the proposed technique are in good agreement with the experimental data. All the prediction points fall within the scatter band of +/- factor of 2. The damage was predicted to initiate at a distance offset from the notch tip. As the acuity increases, the damage initiation site shifts further away from the notch.

Abstract: The purpose of this research is to identify the optimal condition of the wire arc spray technique equipped with the gas atomization system using central composite design (CCD) of response surface methodology (RSM) in Minitab 18 software. Two independent parameters of the wire arc spray technique were studied, including arc voltage and air pressure. The statistical evaluations showed that both arc voltage and air pressure parameters had effects on the quality of the powder in terms of particle morphology and particle size distribution. Additionally, the arc voltage had the highest effect on particle circularity, whereas air pressure had the highest effect on particle size distribution. Finally, the optimal condition was the arc voltage and air pressure of 36.7429V and 0.5436 MPa, respectively, achieving a maximum particle circularity of 0.8284 and a targeted particle size distribution of 45 μm with the desirability of 0.7566 and 0.9928, respectively.

Abstract: Nanotechnology research has lacked to provide new studies on nanofibers using the electrospinning method, the reasons are attributed that all parameters have been covered by previous studies. Believing that science is in a state of constant renewal leads to the possibility to study a parameter that has not been studied before, which affects the morphology of nanofibers. One of the disadvantages of nanofibers manufacturing is the formation of beads, and controlling the parameter helps reduce these beads. Field emission scanning electron microscope (FESEM) images reveal the formation of nanofibers and surface topography observations by atom force microscopy (AFM) indicates that the roughness is improved by changing the distance between rods of the collector. The rods function as a collector for nanofibers, changing this parameter improves the morphology and diameter of the nanofibers.

Abstract: Indium tin oxide (ITO) thin films with 100 nm thickness were successfully deposited on soda-lime glass substrates by metal oxide electron beam evaporation at room temperature. The deposited films were post annealed via rapid thermal processor (RTP) in vacuum environment at 400 to 550 °C. All deposited ITO thin films were studied on the structural, electrical, and optical properties. Results showed that the post annealing treatment by RTP improved the crystallinity, increased crystallite size, and increased surface roughness values. Higher RTP post annealing temperature also enhanced the electrical performance that led to higher transmittance of ITO thin films.

Abstract: In this work, polystyrene/aluminium (PS/Al) nanocomposites were fabricated based on the various concentrations (0, 1, 5, 10, and 15 mg) of Al nanoparticles using the casting method. The resulting polymer/metal nanocomposites have good optical properties. The optical features such as transmittance and absorbance of the as-fabricated nanocomposites were investigated using the UV-Vis spectrophotometer. The effect of constriction of Al nanoparticles was noticed clearly on the transmittance and absorbance of PS/Al nanocomposites. The samples showed high absorption in the UVB range. Photoluminescence spectra (PL) revealed the UVB region of emission peak with the increasing concentration of Al NPs.