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Shukla A.K.,JBIET Yenkapally | Raghu T.,Near Net Shape Group | Rajesham S.,Pulla Reddy Institute of Technology | Balasunder I.,Near Net Shape Group
Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications | Year: 2014

A material's inherent ability of strain distribution decides forming limits and affects the overall formability. In the present work, aero space grade titanium alloy - Titan 31 developed by MIDHANI India is selected. The material is hot rolled under alpha-beta-rolling process and heat treated at different temperatures and subjected to various cooling rates in the alpha plus beta regime to obtain a fine equiaxed alpha-beta microstructure that ensures high formability . Taguchi's design of experiments approach is used to optimize the processing parameters (temperature, crosshead speed and angle-torolling direction specimen tested) to maximize formability depending on intrinsic material properties. Percentage contributions of these parameters towards maximizing the formability are also determined using analysis of variance. The optimal combination of parameters is evaluated as a temperature of 998 K, a crosshead speed of 1.25×10-5 m/sec and an angle of testing the specimen from rolling direction 45°, among all the parameters selected in the study. © IMechE 2013.


Kandasamy J.,MVSR Engineering College | Manzoor Hussain M.,JNTUH College of Engineering | Rajesham S.,Pulla Reddy Institute of Technology
International Journal of Microstructure and Materials Properties | Year: 2012

Friction stir welding (FSW) experiments were conducted on AA7075 alloys under optimised conditions with copper as external alloy on the faying sides of the base material in thin strip and spray coating form. The idea behind the experimentation is to determine the influence of the formed inter metallic compound (IMC) in enhancing the weld strength, by providing uniform frictional heat input to the top and bottom sides of the plates. Test results of mechanical and metallurgical properties indicate that the interaction of AA7075 alloy with copper, in coating form, enhances the bond strength by formation of Al2Cu and Al4Cu9 IMCs. Lack of metallurgical bond strength due to reduced material flow, caused by the difference in the developed friction heat between the top and bottom sides of the weld in conventional weldments, is considerably reduced by copper coating. High thermal conductivity of the copper in coating form has reduced the temperature gradient and maintained homogenous material flow in the weld zone. Reduction in weld strength is observed in copper strip inserted weldments due to interruption of the unmelted copper particles in aluminium matrix in the weld zone leading to a weak bond. Copyright © 2012 Inderscience Enterprises Ltd.


Kandasamy J.,MVSR Engineering College | Hussain M.M.,JNTUH College of Engineering | Rajesham S.,Pulla Reddy Institute of Technology
Materials and Manufacturing Processes | Year: 2012

Friction stir welding (FSW) experiments are conducted on AA7075 and AA6061 alloys under optimized conditions with copper as intermediate inclusion on the faying sides of the base material assisted by external heating from the root side during the process. The concept behind the experimentation is to minimize the temperature gradient that exists between the top and bottom sides of the plates. The work attempts to relocate the crack initiation point from the root of the retreating side, as in conventional friction stir weldments due to the variation in material flow along the weld cross-section. Analysis of the formed intermetallic compound (IMC) indicates that the interaction of AA7075, AA6061 alloys with copper, in coating form, enhances the bond strength by formation of Al2Cu and Al4Cu9 IMCs. High thermal conductivity of the copper in coating form along with external heating from the root side has minimized the temperature gradient and maintains homogenous material flow in the weld zone and increased bond strength. © 2012 Copyright Taylor and Francis Group, LLC.


Upender G.,Osmania University | Vardhani C.P.,Osmania University | Suresh S.,Osmania University | Awasthi A.M.,Consortium of Scientific Research | And 2 more authors.
Materials Chemistry and Physics | Year: 2010

Differential scanning calorimetry (DSC), optical absorption and Raman scattering studies have been carried out on (90-x)TeO2-10GeO2-xWO3 glasses with 7.5 ≤ x ≥ 30 mol%. The Raman studies show that the glass system contains [TeO4], [TeO3+1]/[TeO3], [GeO6], [WO4] and [WO6] groups as basic structural units. From DSC thermogram, thermal properties such as the glass transition temperature (Tg), onset crystallization (To), thermal stability (ΔT), glass transition width (ΔTg), heat capacities in the glassy and liquid state (Cpg and Cpl), heat capacity change (ΔCp) and ratios Cpl/Cpg of the glass systems have been calculated. The compositional variation of the glass transition temperature (Tg) and the calculated oxygen packing density (OPD), oxygen molar volume (Vo) values have been correlated. The variations in the optical band gap energy (Eopt) and optical basicity (Λth) with WO3 content have been discussed interms of the glass structure. © 2010 Elsevier B.V. All rights reserved.


Kumar A.,JBIET Yenkapally | Balasunder,Defence Metallurgical Research Laboratory | Raghu T.,Defence Metallurgical Research Laboratory | Rajesham S.,Pulla Reddy Institute of Technology
Advanced Materials Research | Year: 2012

High specific strength metals with high formability are paramount requirement for maximizing productivity of structural components, aircraft panels and engine components in Automotive and aerospace industry. The material must be suitably processed for better strength and more formability. The formability depends upon several factors one of which is grain size. Finer the grain size better is the formability. In the present study the influence of temperature of thermomechanical treatment on the microstructure of titanium alloy (Titan 31) has been studied to identify suitable thermo-mechanical treatment that refines the grain size. The material was subjected to hot rolling at different temperatures in the range 800°C -900°C. Subsequently the material was subjected to annealing as well as normalizing. Grain size and hardness measurements were carried out to identify suitable thermo-mechanical treatment. The study revealed that rolling at 800°C followed by annealing at the same temperature resulted in finer grain size and low hardness that are conducive for better formability. © (2012) Trans Tech Publications, Switzerland.

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