Key Engineering Materials Vol. 833

Abstract: Bullet cases are usually made of Cu-28Zn alloy through various kinds of process such as cold rolling, deep drawing, and annealing. Alloying is needed to improve properties that increase forming capabilities of cartridge brass, one option is by addition of Al. Samples used in this research were prepared by melting Cu, Zn, and Al ingots in an induction furnace, followed by gravity casting. As cast samples were homogenized at 800 °C for 2 h followed by cold rolling for 5, 10 and 20 %. Annealing was conducted on the 20 % deformed samples at 300, 400, and 600 °C for 30 min. Hardness and microstructures formed by each treatment were then evaluated using Vickers microhardness test as well as optical and scanning electron microscopy. Addition of Al deteriorated Cu-28Zn alloy forming capabilities by reducing its ductility. It is also found that addition of Al reduced recrystallization temperature. Partial nucleation was found to occur locally around the edge of samples at 300 °C and 400 °C. Annealing at 400 °C exhibited γ phase precipitation due to the decomposition of β phase. While, homogeneous full recrystallization was achieved at 600 °C.

Abstract: Acrylonitrile-butadiene-styrene (ABS) is one of the most widely used plastic. The application of ABS increases rapidly in industries recently. The drawback of the increasing demand of ABS is the increment of ABS waste. Huge increment in ABS waste has led to the increasing of environmental pollution. The demand in green technology and sustainability of resources has urged the need of recycling of ABS waste. However, the mechanical properties of the recycled ABS are deteriorated. Hence, this work aims to study the mechanical properties of blend virgin and recycled ABS. The first sample started with 100wt% of virgin ABS. While the second to eleventh samples was a mixing of virgin and recycled ABS at 10wt% incremental recycled ABS. The last sample was prepared using 100wt% of recycled ABS. The results show that the tensile strength of 100wt% of recycled ABS is slightly decreased as compared to 100wt% virgin ABS. Similar trend was observed on traverse rupture strength (TRS) when the TRS for 100wt% of recycled ABS is lower by 8% when compared to 100wt% of virgin ABS. The most significant change is observed on the impact strength. The impact strength for 100wt% of recycled ABS is substantially dropped by 86% as compared to 100wt% of virgin ABS.

Abstract: Quenching process is the most important step in steel heat treatment as this process will determine the properties of the steel such as strength and hardness. Different cooling rate and thermal conductivity provided by the quench medium affect strongly to the mentioned steel properties. Recently, studies for nanoparticle added in the quench medium are developing rapidly. This nanoparticle added fluid is known as nanofluid and could affect the thermal property of the quench medium which ultimately changes the properties of the steel. The nanoparticle composition in nanofluid will affect its thermal property. In this research, carbon was used as the nanoparticle. The composition variations were 0.1, 0.3, and 0.5 weight percent in 100 ml distilled water. Pure distilled water was also used as a comparison control. Planetary ball-mill were utilized for 15 hours at 500 rpm to produce nanosized carbon particle. Field-Emission Scanning Microscope (FE-SEM) and Energy Dispersive X-Ray (EDX) were used to check the particle size, shape and purity of the carbon nanoparticles. These nanofluids were then used to quench S45C carbon steels samples annealed at 1000°C for 1 hour. Samples were attached with a thermocouple which connected to temperature data logger to observe the cooling rate of the quench medium. The quenched samples were be tested to get the information of hardness and metallography analysis for supporting data.

Abstract: In today’s industrial scenario, the requisite for elevated efficiency, better economic viability and higher quality asks for immense improvements in the cutting process stability. Such machining at higher cutting speeds and cutting depths causes an immense amount of heat generation at the work tool interface. The industry makes utilization of cooling techniques to contravene these ill-effects. These techniques make utilization of chemical coolants which are non-biodegradable in nature and consumed in immense quantities. In this study the role of minimum quantity lubrication (MQL) or green machining was experimentally evaluated when utilizing nanoparticle enriched coolants. The effect on the wear and roughness values while turning commercially pure Titanium (Grade 3) was analyzed. Experimentation was performed in two phases. In the first phase, the comparison in dry, flood and MQL process was made. The experimental design was composed factorially and 16 experiments were performed. Analysis was carried out utilizing ANOVA and the results were compared. In the second phase, a graphical cognation was established between the coolant application rate with both surface roughness and flank wear values. It was concluded that the nanoparticle enriched coolant i.e. the “eco nanomist”technique was more efficacious when machining the biocompatible Titanium grade 3.

Abstract: In this research, mild steel weldments are tested by varying nickel content into the weld beads. Three mild steel plates have been joined using three electrodes with similar chemical composition except nickel content 0%, 9-11% and 19-21% respectively, by SMAW process and keeping heat input constant at all. The performance of welded specimens was evaluated by Charpy V-notch impact tests under different temperature conditions (25°C, 0°C, -20°C, -40°C, -60°C). It was found that the weldment with 0% nickel content is suffering rapid transition from ductile to brittle at-60°C, thus toughness reduces to approximately 1/5th of its value at room temperature. Microstructure revealed that at inter-dendritic regions mainly martensite was found. In dendrite core regions of the low carbon weld metals, a mixture of upper bainite, lower bainite and a novel constituent coalesced bainite formed. The fractured surface pattern was also observed using SEM, to reveal the ratio of area underwent ductile or brittle type of failure.

Abstract: This paper presents an alternative algorithm for solving the laser cutting path problem which was modeled as Generalized Traveling Salesman Problem (GTSP). The objective is to minimize the traveling distance of laser cutting of all profiles in a given layout, where a laser beam makes a single visit and then does the complete cut of individual profile in an optimum sequence. This study proposed a hybrid method combining population-based simulated annealing (SA) with an adaptive large neighborhood search (ALNS) algorithm to solve the cutting path problem. Recombination procedures were executed alternately using swap, reversion, insertion and removal-insertion through a fitness proportionate selection mechanism. In order to reduce the computing time and maintain the solution quality, the 35% proportion of population were executed in each iteration using the cultural algorithm selection method. The results revealed that the algorithm can solve several ranges of problem size with an acceptable percentage of error compared to the best known solution.

Abstract: This article presents multi-response optimization of friction stir welding of dissimilar Al 6061-Titanium alloy using Taguchi based grey relational analysis. Taguchi’s L₉ orthogonal array was used for designing the experiments. Process parameters considered for the experiments were rotational speed, traverse speed and tilt angle. Ultimate tensile strength, yield strength, and % elongation were the responses measured which all are larger-the-better characteristics. Based on grey relational grade, optimum levels of process parameters were identified and further ANOVA analysis was carried out to find most significant process parameter.

Abstract: Metal Injection Molding (MIM) is an application of Powder Metallurgy (PM) and Plastic Injection Molding currently being developed to produce precisely-small components. Most of the metal applications using PM are stainless steel fabricated by a gas atomizer. In this study, an atomizer is designed and fabricated to produce stainless steel powder by using a free fall gas atomization method. The stainless steel used in this study is AISI 304 atomized with the diameter sizes varying from about 3 mm, 5 mm, and 7 mm. The variables of diameter size results are the lowest melt flow rate produces the smallest mean diameter, but no significant difference on the sphericity of powder morphology. While the gas pressure variation results shows that metal powder with smaller size will be produced more using the high gas pressure. The gas atomizer have successfully produced metal powder with the size <40 μm and have a spherical shape. The well rounded sphericity for melt flowrate 0.41x10^-3 m³/min, 1.14 x10^-3 m³/min, and 2.24x10^-3 m³/min are 60.0%, 36.0%, and 55.2% respectively.

Abstract: In recent times, aerospace, chemical industries and nuclear plant have usually used Inconel 718 alloy because of its excellent mechanical and chemical properties at elevated temperatures. It falls under the category of difficult-to-cut materials due to its high toughness, poor thermal conductivity and high hardness. The set-ups for electric discharge drilling (EDD) and powder-mixed electric discharge drilling (PM-EDD) were developed, and experiments were conducted on them separately. This research shows a comparative study amid producing holes by EDD and PM-EDD in Inconel 718 alloy workpiece with copper tool electrode. SiC was used as an abrasive powder because of its better thermal conductivity in order to get properly mixed with dielectric in a separate tank. Output response was assessed in the form of material removal rate, under the influence of discharge current, duty factor, pulse-on-time and tool speed, as the input parameters.