Pengaruh Kecepatan Dan Temperatur Uji Tarik Terhadap Sifat Mekanik Baja S48c

Influence of Strain Rate and Temperature of Hot Tension Testing on Mechanical Properties of Medium Carbon Steel S48C. The characterization of S48C by hot tension testing was done to understanding the influence of temperature and strain rate for S48C flow stress, that close relationship with its forge ability. The hot tension testing was performed on temperatures and strain rates variation (T 850, 900, 950 0C and έ 0,01;1 s-1). The result of hot tension testing showed that increasing temperature decreases ultimate tensile strength (UTS) and flow stress of S48C. The higher decreasing of UTS is on 950 0C about 85% from room temperature condition, while the higher decreasing of flow stress has occurred on 950 0C about 31 % compare to conditions of temperature 850 0C, strain 0,23 & strain rate (έ)1 second-1 and about 27% compare to the same conditions but έ= 0,01 second-1 . For increasing strain rate from 0,01 to 1second-1 on the temperature range (850-950 0C) increases UTS about 33 - 50 % and flow stress about 46-53%

Punch Force Behavior during Micro V-Bending Process of the Copper Foil

Sheet metal bending is defined as a straining process of flat strip material around a linear axis. The micro V-bending process was conducted to investigate its punch force behavior with 0.1 mm thick copper foil. The V-shaped configuration of the punch and die provides a simplicity of tools and an ability to produce different bending angles with a single tool. During the straining of material, a unique force profile, which is related to punch trajectory, occurs. The process was performed with the punch speeds 0.5 mm/s, 1.0 mm/s, 5.0 mm/s and 10.0 mm/s. The results showed that the punch force profile consists of the free-bending stage and the coin-bending stage. In the free-bending stage, the force magnitude was not influenced by the punch speed for the same geometrical and mechanical properties of the sheet material. Furthermore, during the coin-bending stage, the force magnitude increased significantly since the material needed to be bottomed

PENGARUH KECEPATAN DAN TEMPERATUR UJI TARIK TERHADAP SIFAT MEKANIK BAJA S48C

Influence of Strain Rate and Temperature of Hot Tension Testing on Mechanical Properties of Medium Carbon Steel S48C. The characterization of S48C by hot tension testing was done to understanding the influence of temperature and strain rate for S48C flow stress, that close relationship with its forge ability. The hot tension testing was performed on temperatures and strain rates variation (T 850, 900, 950 0C and έ 0,01;1 s-1). The result of hot tension testing showed that increasing temperature decreases ultimate tensile strength (UTS) and flow stress of S48C. The higher decreasing of UTS is on 950 0C about 85% from room temperature condition, while the higher decreasing of flow stress has occurred on 950 0C about 31 % compare to conditions of temperature 850 0C, strain 0,23 & strain rate (έ)1 second-1 and about 27% compare to the same conditions but έ= 0,01 second-1 . For increasing strain rate from 0,01 to 1second-1 on the temperature range (850-950 0C) increases UTS about 33 - 50 % and flow stress about 46-53%.Keywords : forgeability, flowstress, temperature, strain rate, hot tensile testin

SYNTHESIS OF EMPTY FRUIT BUNCHES CARBON POLYMER COMPOSITES AS GAS DIFFUSION LAYER FOR ELECTRODEMATERIALS

SYNTHESIS OF EMPTY FRUIT BUNCHES CARBON POLYMER COMPOSITES AS GAS DIFFUSION LAYER FOR ELECTRODEMATERIALS. Empty Fruit Bunches (EFB) of oil palmhas been used, for example, for biofuels, automotive components, particle board, as a carbon source. Carbon material scan be widely used for many applications, for hydrogen storage, conductive or reinforcement plastics, catalyst supports, batteries and fuel cells. In this study, EFB carbon powder has been used as a raw material to make sheets of carbon-polymer composites. The composition of the composite sheet was varied, the electrical properties of the sheets were measured to determine the potential application as a Gas Diffusion Layer for Proton Exchange Membrane Fuel Cell (PEMFC) electrodes. Composites made with carbon composition weight % compared to the polymer are 65/35, 70/30, 75/25 and 80/20. The materials used is EFB carbon powder as a result of the pyrolysis temperature of 900 °C for 1 hour, then crushed and sieved to 200 mesh size, and the polymer was ethylene vinyl acetate. The rawmaterials are mixed in a solvent xylene, and printed using tape casting method, then dried at room temperature. The electrical properties were tested using a HIOKI 3522-50 LCR meter HiTESTER The measurement results show that the greater the ratio of carbon to polymer, the higher the electrical conductivity, the values are between 1.54 S/m-11.34 S/m.Morphology of the composite sheet was observed using Scanning Electron Microscope (SEM) to determine the distribution of carbon and polymer. According to the measurement of morphology and electrical conductivity, the composite is suitable for the gas diffusion layer of the PEMFC electrode

Effect of Annealing Temperature on Microstructure and Mechanical Properties of Ultrafine Grained Brass Produced by Equal Channel Angular Pressing

The present study investigated the mechanical properties and microstructure of ultrafine grained (UFG) brass processed by four passes of equal channel angular pressing (ECAP) and annealed at elevated temperatures. The mechanical properties of all samples were assessed using tensile and micro-hardness tests. Microstructure analysis was performed using optical microscopy (OM) and scanning electron microscopy (SEM). Ultimate tensile strengths (UTS) and yield strengths (YS) of 878 and 804 MPa, respectively, ductility of 15%, and hardness of 248 HV were obtained for samples processed by four passes of ECAP with equivalent true strain of 4.20. Annealing at 300°C caused UTS and YS to decrease significantly, to 510 and 408 MPa, respectively, ductility to increase to 28%, and hardness to decrease to 165 HV. Fractography analysis of un-annealed samples after four ECAP passes showed small brittle fractures with shallow dimpling. Ductile failures were found on annealed samples. After four ECAP passes, the microstructure of un-annealed samples was UFG and dominated by lamellar grain with shear band. In contrast, after annealing, the microstructure changed due to recrystallization, showing nucleation and grain growth

EFFECT OF SULFUR IN THE REDUCTANTS ON SULFIDATION MECHANISM OF NICKEL LATERITE

Processing nickel laterite conventionally, namely by pyrometallurgy method, requires high temperature and energy, results in a costive process. Due to its lower temperature reduction process, selective reduction with additives could be an alternative in nickel ore processing. Additives such as sulfur/sulfate have a critical role in promoting the low melting point phase. Sulfur is also found in coal. Therefore, it is important to investigate the effect of sulfur content in reductant on selective reduction of lateritic nickel ore. In this work, the effect of sulfur content (2.68% and 5% S) in anthracite coal as a reductant on selective reduction of limonitic ore was studied clearly. Nickel ore, reductant and sodium sulfate were mixed homogenously and pelletized up to 10-15 mm in diameter. Pellets were reduced using a muffle furnace at 950 to 1150°C for 60 min. Reduced pellets were crushed into -200 mesh before separating the ferronickel and its impurities using a wet magnetic separation process. The result showed that the anthracite coal with 5% S produced concentrate containing 3.56% Ni with 95,97% recovery, which is higher than 2.68% S. The sulfur content in reductant could replace the addition of sulfur/sulfate as the additives in the selective reduction of lateritic nickel ore

Preliminary Investigation of Micro-V-Bending

Bending in sheet metal forming is defined as uniformly straining process around a linear axis. A V-bending process is normally used in sheet metal working due to the tool and process simplicity. The main problem in bending process is a springback occurrence which causes an error in part dimension. In a micro level, the springback angle is difficult to be assessed because of the influence of size effects in all aspects of the system. The springback behavior has been investigated in many previous kinds of research. However, the springback correction is still needed to be studied extensively so that it can be implemented reliably in micro-bending. The purpose of this research is to investigate the influence of punch velocity and holding time to the springback angle. The process is performed to the 0.1 mm thickness of copper foil. The punch velocities are 0.1 mm/s, 1 mm/s, and 10 mm/s. While the variation of holding time, which is set during the bottoming stage, are 7 s, 9 s, and 11 s. The result shows that the punch velocity clearly influences the springback angle. In addition, the holding time during the bottoming stage is a potential factor in springback angle correction

Influence of Strain Rate and Temperature of Hot Tension Testing on Mechanical Properties of Medium Carbon Steel S48C

The characterization of S48C by hot tension testing was done to understanding the influence of temperature and strain rate for S48C flow stress, that close relationship with its forge ability. The hot tension testing was performed on temperatures and strain rates variation (T 850, 900, 950 0C and έ 0,01;1 s-1). The result of hot tension testing showed that increasing temperature decreases ultimate tensile strength (UTS) and flow stress of S48C. The higher decreasing of UTS is on 950 0C about 85% from room temperature condition, while the higher decreasing of flow stress has occurred on 950 0C about 31 % compare to conditions of temperature 850 0C, strain 0,23 &amp; strain rate (έ)1 second-1 and about 27% compare to the same conditions but έ= 0,01 second-1 . For increasing strain rate from 0,01 to 1 second-1 on the temperature range (850-950 0C) increases UTS about 33 - 50 % and flow stress about 46-53%.<br