Material Science and Engineering Technology VI

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Authors: Imam Basori, Hafsah I. Pratiwi, Bondan T. Sofyan
Abstract: Deformation characteristics of brass alloy are still under discussion, particularly concerning the critical level of when the change of deformation mechanism occurs. Previous research showed that the addition of Mn on brass alloys resulted in grain refinement and mechanical properties alteration. However, the effects of Mn on the deformation characteristic of brass alloys have not been investigated. In this research, Cu-Zn-xMn alloys were manufactured by gravity casting process using pure Cu and Zn ingots, as well as Mn chips as the feeding materials. Mn addition was varied to 1.26, 3.48, and 5.83wt.%. As-cast samples were homogenized at 800 °C for 2 h in a muffle furnace. The samples were then cold-rolled with the level of deformation of 20, 40, and 70 %. Samples characterization includes chemical composition analysis, microstructure observation, tensile and hardness testing. The results showed that addition of Mn for 5.83 wt.% and above created β’ phase, which is richer in Mn compare to that in the matrix. This phase segregated in the grain and along the grain boundary with irregular forms. Significant increase in hardness, yield and tensile strengths was observed with addition of Mn. The maximum elongation was achieved by addition of 3.48 wt.% Mn, while further addition tended to decrease it. At 20% deformation, slip dominated and its density reduced with addition of Mn. When the deformation level increased to 40%, twinning replaced slip as the predominant mechanism. Twinning density is slightly increase with the presence of Mn. Further deformation at 70% produced shear bands and flattened the β’ phase. Greater Mn content led to formation of more shear band.
Authors: Sonika Sahu, Mohd Zahid Ansari, Chong Du Cho
Abstract: Numerical simulation is performed to study the deformation and failure modes of Al 1100 plate of 2.4 mm thickness, subjected to low-velocity impact. Blunt and hemispherical nose shaped impactors are used in this study. The quasi-static tensile test is performed at a strain rate of 0.01/s to obtain the Johnson-Cook material parameters which are used in numerical simulation software, ABAQUS/CAE to perform impact analysis. Mesh convergence study is carried out to decide the appropriate number of elements for numerical analysis. The impact behavior of Al 1100 plate for each impactor shapes are studied at 22 J impact energy. Result indicate that increased in the nose radius of impactor will increase the amount of deformation energy for aluminium plate.
Authors: Suok Min Na, Nicholas J. Jones, Alison B. Flatau
Abstract: Grain growth and grain boundary character distribution relationships in Fe-Ga rolled sheet is investigated to study the influence of H2S gas content in argon on the development of selective grain growth through secondary recrystallization. Abnormal growth of (011) grains was predominant at the low content of H2S gas, while (113) grain growth was well developed at contents higher than 1.33% H2S. On the other hand, the development of (001) grains was challenging to produce because it is very sensitive to the anneal environment and has a relatively low fraction of high energy grain boundaries associated with misorientation angles that determine the mobility of boundaries.
Authors: Hirotaka Kato, Hiroto Ueki, Keitaro Yamamoto, Kazufumi Yasunaga
Abstract: Burnishing, which is one of the most powerful processes for microstructural evolution, was performed by a cemented carbide ball (6 mm in diameter) that was loaded and fed on the flat surface of a rotating disk specimen of carbon steel using a lathe machine. The effects of burnishing process parameters such as force and rotation speed on the surface roughness, microstructure and hardness were investigated. In addition the dry sliding wear properties of the burnished surface layers were studied using a ball-on-disk friction method. It was found that the burnished surface was much smoother than as-turned surface (before burnishing) owing to the plastic flow of the surface asperities through the rubbing motion of the burnishing ball. Nanostructure in the 30 - 50 nm grain size range was formed in the burnished sub-surface layer, and the hardness significantly increased due to the grain refinement. The nanocrystalline microstructure was observed at high burnishing forces and speeds owing to the high strain and strain rate of the friction-induced plastic deformation. Moreover the burnishing process reduced the specific wear rates by a factor of six. Thus we concluded that the wear resistance of carbon steel can be significantly improved by burnishing due to the smooth surface and nanostructured sub-surface layers.
Authors: In Soo Kim, Su Kwon Nam, Gwang Hee Kim, Dong Nyung Lee
Abstract: The Goss texture, or {110}<001>, shows soft magnetic property due to the <100>. Therefore, it is one of the most important texture in Si steels. The Goss texture is one of the shear deformation texture in steel which has bcc structure. During the asymmetric rolling, shear deformation is imposed on steel sheets. To obtain the Goss texture, the carbon and Si steel sheets were asymmetrically rolled by 50-85% reduction in thickness at room temperature and at 770 °C. The asymmetric rolling of steel sheets gave rise to the well-developed Goss texture to them.
Authors: Sally Elkatatny, Mohamed Abdel Hady Gepreel, Atef Hamada
Abstract: The microstructure and hardness changes of a non-equiatomic Al5Cr12Fe35Mn28Ni20high-entropy-alloys (HEA) with cold rolling are presented here. Using a variety of characterization methods, it is shown that the alloy is single FCC phase structure which doesn't change with cold rolling up to90%CR. With increasing the cold rolling reduction ratio, the hardness increased and the dendritic structures are broken and refined.
Authors: Kai Xu, Shu Quan Zhang
Abstract: A lap welding experiment of DP590 steel and 6061 aluminum plate is carried out by using Heating Friction Stir Spot Welding (HFSSW) to study the influence of welding parameters on the forming quality. The results show that a lap joint with better forming can be obtained for the dissimilar metal of steel and aluminum. Under the condition that the rotating speed of the stirring tool is 1000r/min, the penetration depth, 0.2mm, the dwell time, 90s, the welding pressure, 0.2Mp, and the flow rate of cooling air, 20L/min, the forming quality of the surface of the joint line is good & bright, and the exit hole is also smaller. The mechanism of heat production is revealed in the following: the main heat is produced by the friction between the stirring tool shoulder and the welded part & between the probe and the welded part as well as by the latent heat resulted from the plastic deformation of the material in joint line during welding.
Authors: Bryan B. Pajarito, Andrew Joelle F. Caguntas, Niño B. Felices, Honesto Ovid S. Tubalinal, Giselle Lou D. Leuterio
Abstract: Acrylic coatings were modified by adding 0.5 and 1.0% (v/v) of epoxysilane-treated (aluminosilicate, muscovite, nepheline syenite, and wollastonite) and alkoxysilane-treated (aluminosilicate) mineral fillers. Corrosion behavior of coated carbon steel specimens was studied using polarization method. Wetting behavior and adhesion of specimens were evaluated by static contact angle and cross-cut tape test. Addition of silane-treated mineral fillers dramatically improved the corrosion resistance of acrylic coating, with composite coating filled with alkoxysilane-treated aluminosilicate at 0.5% concentration showing significantly low corrosion tendency and rate in 2 M HCl solution. Contact angle also increased with the addition of fillers, with composite coating containing alkoxysilane-treated aluminosilicate at 0.5% yielding the highest mean value. Adhesion of acrylic coatings was enhanced after addition of fillers at 0.5%, with composite coatings filled with wollastonite and alkoxysilane-treated aluminosilicate giving the lowest percent area removed after application of adhesive tape. Alkoxysilane-treated aluminosilicate was found consistent in improving the anti-corrosion characteristics, water resistance, and adhesion to carbon steel of acrylic coatings.
Authors: Tung Sheng Yang, Chun Wang, Li Xiu Liu, Shuen Huei Yao
Abstract: Aimed at AISI-1010 low carbon steel pulley components, a finite element method-based metal forming simulation software of DEFORM 3D was used to simulate and analyze the near net forging process for the low carbon steel pulley, and to design forging molds. This technology was used in the pulley tooth forging in conjunction with the servo press-based servo motion curve technology. First, the cold forging process of the pulley preform forging and the near net forging were simulated. Also, the applications of the pulse wave servo motion curve in the pulley tooth forging was simulated, which was compared with the traditional motion curve-based forging forming, where the comparisons focused on the maximum forming force and maximum equivalent stress. The results indicated that the maximum forming force and the maximum equivalent stress of the punch caused by the pulse wave servo motion curve was smaller than caused by the traditional motion curve.
Authors: Wan Wu Shen, Feng Qiang Nan, Chun Jiu Zhu, Jun Hui Lu
Abstract: The rheological properties of propellant are several key factors in the process design, which affect the quality of propellant processing that determines the weapon's performance. The main technological parameters influencing the quality of nitroguanidine-based propellant are nitroguanidine (NGu) content, solvent ratio and temperature. Rheological test of the propellant dough was carried out by using capillary rheometer. The effects of these main process parameters on the shear stress and shear viscosity of the propellant during the rheological process were discussed. Power law model, modified Bingham model and Cross model were used to fit the rheological data. The results show that Power law model is better than the other two models, explaining Power law model can be used as the constitutive equation to describe the actual rheological behavior of the propellant extrusion moulding more accurately.

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