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The effects of artificial-aging temperature on tensile strength, hardness, microstructure, and fault morphology in AlSiMg

Andoko, Yanuar, Puspitasari P., Ariestoni T. B.

Journal of Achievements in Materials and Manufacturing Engineering

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2020

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Vol. 98, nr 2

49--55

EN

Purpose: This research examined the effects of artificial-aging temperature and time on tensile strength, hardness, microstructure, and fault morphology in AlSiMg. Design/methodology/approach: This research was conducted using aluminium alloy at 120°C, 150°C, and 180°C artificial-aging temperature and 6 hours holding time. The tensile test used ASTM B211-03 standard and hardness test adapted to ALCOA 6061 standard. Findings: Tensile test results indicated the highest tenacity on aluminium alloy at a 150ºC temperature that was 47.263% strain level. In addition to the strain level, this research also obtained the highest tensile strength level at 180ºC that was 62.267 kgf/mm2 and the highest hardness value that was 110 HV. The increase in tensile strength and hardness at 180°C was caused by the increase in Mg, Si, and Al. Based on the microstructure test, the highest tenacity was obtained at 150°C temperature as the result of closed and gathered Mg2Si precipitates; while at 180°C temperature, the precipitates appeared to be more distributed, causing a rise in hardness value and tensile strength. AlSiMg tenacity also exhibited from the number of dimples compared to cleavages at 150°C temperature. Research limitations/implications: The limitation that found in this research was conducted using AlSiMg aluminium Al6061 specimen with an artificial-aging treatment at 120ºC, 150°C, and 180°C temperature for 6 hours and then compared to the raw material. AlSiMg tensile specimen was made according to ASTM E8-E8M standard. Practical implications: This research can be applied in industrial manufacture process to find tensile strength, hardness, microstructure, and fault morphology of Al6061 alloy. Originality/value: According to research result, can be understood that by conducting these experiments, Artificial-aging treatment temperature variations in AlSiMg aluminium alloy could increase hardness.

2

The effect of thermal processing parameters on the mechanical properties of aluminium alloy foam

Puspitasari D., Ginta T. L., Puspitasari P., Mustapha M.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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Vol. 91, nr 1

12--17

EN

Purpose: The purpose of this study was to investigate the influence of three thermal processing parameter called stress relieving on mechanical properties of the aluminium alloy foam. Design/methodology/approach: The samples were undergone by stress relieving method using vacuum furnace. Hardness measurement was carried out using microhardness Vickers at 150 mN load and 15 s loading time. Compressive strength, plateau stress and energy absorption were calculated using a universal testing machine. Findings: It was found that the highest value of hardness of 192.78 Hv was obtained when the stress relieving process is set with the following parameters: heating (500°C); holding time (120 min) and stabilization temperature (450°C). Since higher heating temperature and longer holding time produce sample with larger grain size and has an adverse effect on the hardness value It was revealed that the mechanical properties of aluminium alloy foam were enhanced when the heating temperature was decreased, holding temperature was diminished and the stabilization temperature was increased. Overall, the presented results showed that the thermal processing parameters such as heating temperature, holding time and stabilization temperature have a significant influence on improving the mechanical properties of aluminium alloy foam. Research limitations/implications: The properties of closed-cell aluminium alloy foam are highly sensitive and depend on the post heat treatment process. The processing parameters should be controlled in order to manipulate the properties of closed-cell aluminium alloy foam. Originality/value: To investigate the influences of these processing parameters on the physical and mechanical properties of the closed-cell aluminium alloy foam.

3

The analysis of strength and fracture morphology of Al-Si compound made from moulding sand formulation with bentonite binding material and Portland cement

Andoko F., Puspitasari P., Gapsari F.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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Vol. 89, nr 1

5--12

EN

Purpose: This research aimed to analyse the casting result of Al-Si compound used formulation of moulding sand with bentonite binding material and Portland cement. Design/methodology/approach: Bentonite binding material’s type consisted of swelling (Na-bentonite) and non-swelling (Ca-bentonite). Optimum formulation of the moulding sand was 4% of swelling bentonite and 6% of Portland cement, 6% of non-swelling bentonite and 4% of Portland cement. The optimum formulation result of molding sand with bentonite binding material and Portland cement was used in Al-Si compound casting. The result of Al-Si compound casting strength was examined which in terms of its tensile strength, toughness, and hardness. Besides the three tests, the result was also supported by the fracture shape morphology of tensile test and impact toughness test result. Based on the Al-Si compound tensile test result, it was found that the best value was obtained when using 105.52 MPa of swelling bentonite. Findings: The impact toughness test result presented that the use of non-swelling bentonite produced better toughness value which was 0.00592 J/hour while the mickroVickers hardness test result showed that Al-Si compound result using non-swelling bentonite produced 111.04 HV hardness. Based on the fracture morphology test result using SEM of Al-Si compound casting result using swelling and non-swelling bentonite after being tested its tensile strength and impact toughness showed that the same fracture which was brittle fracture tended to appear. Research limitations/implications: In this casting process, combination which is being used is bentonite (swelling and non-swelling) and Portland cement as mould sand binding material. Practical implications: The combination can be used to find the bentonite type that can produce binding material formula with high binding level which can minimize defects on the resulted casting products. Originality/value: In this study swelling and non-swelling bentonite mixed with certain level of Portland cement combination are used.

4

Optimization of multistage artificial aging parameters on Al-Cu alloy mechanical properties

Tsamroh D. I., Puspitasari P., Andoko, Permanasari A. A., Setyawan P. E.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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Vol. 87, nr 2

62--67

EN

Purpose: This research is aimed to describe heat treatment process by using multistage artificial aging for Al-Cu alloy with Taguchi method in Minitab 16 to optimize the heat treatment parameters. This research conducted due to the applied of aluminium alloy in automotive industrial and aircraft industrial that has good properties for fabrication. Design/methodology/approach: Methodology that use in this paper is experimental design with statistical approach. Three controllable parameters were selected, they were temperature aging, holding time of aging, and the number of stages. The hardness value and impact value after multistage artificial aging were chosen as quality characteristics. The experiment was performed using orthogonal arrays of L9 (33). Findings: The finding that resulted in this research are the most significant parameters that affected hardness and toughness value of Al-Cu alloy against multistage artificial aging. The optimal hardness and toughness for Al-Cu alloy were obtained with heat treatment at temperature 200ºC, holding time for 6 hours, with two stages artificial aging. Research limitations/implications: The limitation that found in this research is even optimal level had been determined, it is unable to determine the true optimal value of each design parameters. Practical implications: This optimization process can be applied in manufacture process in industrial without spend expensive cost and time. Originality/value: According to research result, can be understood that by conducting these experiments, the impact value and the hardness value of Al-Cu alloy increase with multistage artificial aging treatment.

5

Morphology of aluminium with nickel addition on sand casting process

Puspitasari P., Fauzan R., Ginta T. L., Mustapha M., Puspitasari D.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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Vol. 87, nr 1

13--17

EN

Purpose: This research aimed to examine the morphology, elemental changes, and phase in the aluminium cast alloys with variations in nickel addition of 1%, 2% and 3%. Design/methodology/approach: Aluminium 98% was melted in sand casting process. The sand casting process was operated at 7000C and atmospheric pressure. The addition of nickel contain of 92.19% of its element. Specimens consist of 4 pieces Al-Ni with the size of 1 x 1 x 0.5 cm for morphological testing, while for phase identification testing consist of 4 pieces Al-Ni with the size of 1 x 1 x 2 cm. The morphological testing was performed using FEI Inspect S50 Scanning Electron Microscope (SEM) and the phase characterisation was conducted using Nikon ME5 Optical Microscope. Findings: The results showed that the addition of 1% nickel in the aluminium cast product could affect the morphology in granular shape with as similar size, at 2% nickel addition also has granular shape, while at 3% of nickel addition, the morphology of Al-Ni was in elongated shape. Phase identification of Al-Ni cast alloy shows that there were Al matrix with nickel that spread in grain boundary of Al. By increasing the percentage of nickel, it shows that the nickel dominated the grain boundary of Al. These results shows that Al-Ni alloy can be produced at simple route on sand casting process. Research limitations/implications: Sand casting process with 80% silica sand, 10% bentonite, 5% water. Raw material of aluminium contains of 92-99% of purity. Nickel as addition element contain of 90-92% purity. Practical implications: The addition of nickel should be prepared wisely in term of the calculation of alloying treatment because it will effect the mechanical properties of Al alloy itself. This research can be improved by varying the temperature of casting process, variation of nickel percentage, and observation of mechanical properties of Al-Ni alloy. Originality/value: Simple route of making Al-Ni alloy using sand casting method in laboratory and also the observation of nickel addition in aluminium matrix as the result of casting product.

6

Hardness and microstructure investigation of steel rod ST 42 coated by chrome steel using wire arc spray coating

Puspitasari P., Yudhistantra A., Haryono A. S., Dika J. W., Achyarsyah M., Shikh Zahari S. M. S. N.

Journal of Achievements in Materials and Manufacturing Engineering

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2018

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Vol. 90, nr 2

69--76

EN

Purpose: This research aimed to examine the hardness, surface roughness and microstucture in the Steel Rod ST 42 coated by chrome steel using wire arc spray coating with variations in spraying current of 140, 155, 170 and 180 Ampere. Design/methodology/approach: There was 12 specimens consisting of 3 specimens for each variation of the electric current coating. The specimens were cut to 30 mm in length and 27 mm in diameter; as many as 4 x 3 pieces, each specimen was cut to a size of 30 mm and put on a lathe to be drilled 1 mm deep. The hardness testing employed the Brinell hardness test method. The hardness testing process was followed by microstructure observation and SEM-EDAX testing. Findings: The highest hardness was 110.77 HRB by coated at 155 A and it contained many reinforcing inclusions and larger Cr. The lowest current of 140 A had many porosity holes and partially-melted particles, causing Cr grains did not attach perfectly. The current with 170 A had few inclusions and hence a decrease in hardness and at 180 A consisted of a low carbon content and evenly distributed inclusions and Cr and relatively large grain size, and thus the hardness rose. Research limitations/implications: The material of steel rod ST 42 coated by chrome steel. Practical implications: The variation of current should be prepared wisely in term because it will effect the hardness, surface roughness and microstucture. This research can be improved by varying the voltage, gas pressure, particle velocity, particle temperature, and molten wire width. Originality/value: Simple route of making steel rod ST 42 coated by chrome steel using wire arc spray coating and also the investigation of hardness, surface roughness and microstucture in steel rod ST 42 coated by chrome as the result.

7

Statistical optimization of stress relieving parameters on closed cell aluminium foam using central composite design

Puspitasari D., Ginta T. L., Mustapha M., Sallih A., Puspitasari P.

Archives of Materials Science and Engineering

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2018

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Vol. 89, nr 2

55--63

EN

Purpose: This study concerns about the influence of stress relieving parameters on the hardness of closed cell aluminium foam using central composite design. Design/methodology/approach: The responses of three stress relieving parameters: heating temperature, holding time and stabilization temperature are studied and analysed through 20 experimental runs designed according to central composite design. The results of microhardness test corresponded to the microstructural evaluation of closed-cell aluminium foam using optical microscope. Analysis of Variance (ANOVA) technique is employed to study the significance of each parameter on the microhardness property. In this process the design has five levels for each parameter. The stress relieving process of the samples were performed using a vacuum furnace. The hardness test was conducted using a micro hardness tester LM247AT and the microstructure of the samples were obtained using optical microscopy technique. Findings: It was found that the highest value of hardness of 192.78 HV was obtained when the stress relieving process is set with the following parameters: heating (500°C); holding time (120 min) and stabilization temperature (450°C). Since higher heating temperature and longer holding time produce sample with larger grain size and has an adverse effect on the hardness value. Research limitations/implications: Liquid metal and powder metallurgical processing still produces a non-uniform and poorly reproducible cellular structure. This cellular structure demonstrates poor quality difference on decomposition and melting temperature, called anisotropic early expansion. Originality/value: To improve the poor cellular structure quality, stress relieving method is proposed in this study. Stress relieving method can improve the microstructure of the material.