Papers by Author: T. Raghu

Abstract: High specific strength metals with high formability are paramount requirement for maximizing productivity of structural components, aircraft panels & engine components in Automotive & aerospace industry. The material must be suitably processed for better strength & 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 thermo-mechanical treatment (TMT) on the microstructure of titanium ally Titan 31 in order to identify suitable TMT to refine the grain size has been investigated.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 heat treatments. Grain size and hardness measurements were carried out to identify suitable TMT. The study revealed that rolling at 800°C followed by annealing at the same temperature resulted finer grain size and low hardness that are conducive for better formability.

Abstract: Pure nickel sheets are severe plastically deformed by constrained groove pressing technique at room temperature up to three passes. A total strain magnitude of 3.48 is imparted to the sheets and further processing is limited by initiation of surface microcracks. The grain size evolution studied by optical microscopy reveals significant grain refinement at the end of third pass evidently illustrating the effectiveness of groove pressing technique for grain refinement in sheet materials. Vickers microhardness measured during different stages of groove pressing process clearly describes the deformation behaviour in different segments of slant and flat regions. The change in mechanical properties of constrained groove pressed sheet is evaluated by room temperature tensile and microhardness tests. Results showed considerable increase in strength and hardness during initial passes followed by slight drop during third pass.