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Shabani M.O.,Iranian Materials and Energy Research Center | Mazahery A.,University of Tehran
JOM | Year: 2011

In this paper, a relatively new approach is presented in order to predict the microstructure of A356 using finite element technique and artificial neural network. In the training and test modules of the neural network, different primary and secondary dendrite arm spacing obtained from finite element method were used as inputs and eutectic volume percentage, silicon volume percentage, silicon rod spacing, average length of silicon rods and silicon rod diameter were used as outputs. After the training set was prepared, the neural network was trained using different training algorithms, hidden layers and neurons number in hidden layers. The results of this research were also used to form analytical equations followed with solidification codes for SUT Cast software. © 2011 TMS.

Aminikia B.,Iranian Materials and Energy Research Center
Powder Technology | Year: 2012

NanocrystallineTiB 2-TiC composite was readily prepared by self-propagating high-temperature synthesis (SHS) of the mechanically milled powders. Mixture of Ti and B 4C as the starting materials were initially milled for 1, 3, 6 and 9h, and pressed to form the pellets. The green compacts were placed in a tube furnace preheated to 1100°C and 1200°C in argon atmosphere. The samples were characterized by XRD, SEM and TEM analytical techniques. The results showed that, increasing the milling time enhances the formation of TiC and TiB 2 phases and reduces the furnace temperature necessary for the synthesis process. In fact, the powder milled for the longer time, required the lower temperature for the SHS process to occur. © 2012 Elsevier B.V.

Ebadzadeh T.,Iranian Materials and Energy Research Center
Journal of Alloys and Compounds | Year: 2010

Nano-structured mullite was produced from the microwave heating of a mixture of clay and alumina activated mechanically in a planetary ball mill for 30, 50 and 70 h. XRD results showed after 30 h milling time, clay disappeared and alumina and quartz appeared as the only crystalline phases. The maximum specific surface area was 34.92 m2/g for the sample activated mechanically for 30 h. The mullitization was completed for powders milled for 30 and 50 h and heated for 30 min (equal to 1376 °C) in a microwave oven. The maximum density and flexural strength values were measured for samples milled for 30 and 50 h, respectively, and sintered for 30 min. The flexural strength values of these samples were 3 and 4.7 times of the strength value of the sample milled for 2 h and sintered at the same conditions. © 2009 Elsevier B.V. All rights reserved.

Esmaily H.,Iranian Materials and Energy Research Center | Nuranian H.,Iranian Materials and Energy Research Center
Construction and Building Materials | Year: 2012

In this study, the use of alkali activated slag (AAS) in place of usual cementitious materials in the production of autoclave aerated concrete (AAC) was studied. This substitution altered autoclave curing stage by steam curing in AAC production process. In this way, after mixing of AAS paste with aluminum powder, enough time was given to the mixture. The resultant green body was then cured at 70, 78 and 87 °C. To achieve the best results, microscopic pore structure, compressive strength of the body and mini-slump of initial paste were studied. The results approved that AAC can be produced without autoclave by using AAS. © 2011 Elsevier Ltd. All rights reserved.

Hashemi S.H.,Birjand University | Mohammadyani D.,Iranian Materials and Energy Research Center
International Journal of Pressure Vessels and Piping | Year: 2012

The variation of microstructure and mechanical properties in various sub-zones of double submerged arc welded line pipe steel of grade API X65 was investigated. Instrumented Charpy V-notch tests and Vickers hardness experiments were conducted on the fusion zone, base metal and heat affected zone of the weld joint in 14.3 mm thick, 1219 mm outside diameter spiral pipeline. The lowest impact energy and the highest hardness level (160J and 218 HV, respectively) were recorded in the fusion zone. The low energy and high hardness characteristics of the seam weld can be attributed to its cast microstructure and the presence of grain boundary phases (such as proeutectoid ferrite), confirmed by standard metallographic observation. Despite this, service requirements set by the API 5L industry code (minimum impact energy of 73J, maximum hard spots of 350 HV) were fulfilled by the tested steel. © 2012 Elsevier Ltd.

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