Department of Metallurgical & Materials Engineering

&ldquo;IIT Jodhpur is committed to impart quality education to facilitate the creation of qualified, competent and responsible human resources to meet the emerging technological challenges of the world. It is working towards creating an equitable learning platform that is positive, accessible and effective in the face of the modern societal and scientific advancements.

Flexibility in curriculum, in all its academic programs, encompassing elements of teaching, research, creativity, innovation and entrepreneurship is the most unique feature of IIT Jodhpur. The Department of Science and Technology (DST), under the National Mission on Cyber Physical Systems, has identified IIT Jodhpur as a Technology &amp; Innovation Hub in the area of Augmented Reality and Virtual Reality. The institute has also been nominated as the coordinator for the Jodhpur City and Knowledge Cluster by the Office of Principal Scientific Adviser, Government of India.

The sprawling 852-acre IIT Jodhpur campus is a majestic tribute to the deep-rooted diverse cultural heritage of the region. The campus is an architectural masterpiece, which is slated to become an international exemplar of sustainability with net-zero energy, and advanced water and waste management strategies.&rdquo;

IIT Jodhpur

A microduplex stainless steel (IN744) was investigated to understand the source of variation in the parameters of the constitutive relation for superplastic deformation. In the early stage of deformation strain rate sensitivity, grain size exponent and activation energy depend on strain due to microstructural instability. After suitable prestraining such variations are sufficiently reduced and then the experimental data conform to the steady state which is an important criterion in the theoretical models. The Q obtained after suitable pre-straining of the specimens also compares with the activation energy for grain boundary diffusion in contrast to the activation energy for lattice diffusion as reported in the earlier investigations on this material. Refs.

World University root node

Proceedings of the Riso International Symposium on Metallurgy and Materials Science

IMPORTANCE OF PRESTRAINING IN EVALUATING PARAMETERS OF THE CONSTITUTIVE RELATION FOR SUPERPLASTIC DEFORMATION.

Stress (σ)-strain rate ( {Mathematical expression}) data of banded and elongated grain microstructures of the Pb-Sn eutectic alloy were analysed over 298 to 443 K to evaluate microstructural instability during differential strain rate tests in the superplastic region. With reference to a stable equiaxed microstructure exhibiting unique σ- {Mathematical expression} relation, banded structure is more susceptible to strain hardening while the elongated grain microstructure exhibits either strain softening or strain hardening depending on the test temperature. This flow behaviour is considered in terms of a change in grain size, represented by the cube root of the grain volume. Activation energy for grain growth calculated from the differential strain rate test data indicates that the activation energy depends on strain rate and type of microstructure. © 1983 Chapman and Hall Ltd.

Journal of Materials Science

Evaluation of microstructural instability during the differential strain rate test of a superplastic alloy

STRAIN EFFECT ON STRESS-STRAIN RATE RELATIONS OF SUPERPLASTIC IN744 STEEL.

Superplastic behavior of a microduplex stainless steel (IN744) was studied by deforming specimens with initially elongated grains. As a result of deformation, grain growth and breaking up of elongated grains were noticed to occur concurrently. These microstructural instabilities result in strain hardening or strain softening, respectively. This then leads to nonuniqueness in the flow behavior. Some examples of nonuniqueness in stress-strain rate relation include the presence of: strength anisotropy, increase in strain rate sensitivity, constant stress level for varying grain size, and two distinct stress-strain rate curves over comparable test condition for the same initial microstructure. These have been explained by the concomitant microstructural changes and the influence of such changes on instantaneous flow stress. Emphasis is made on the need to eliminate microstructural instability in order to characterize the deformation phenomena under steady state. © 1983 The Metallurgical of Society of AIME.

Metallurgical Transactions A

Influence of nonsteady state behavior on superplastic deformation of a 25.7 Cr-6.6 Ni stainless steel

Materials Science and Engineering

Reply to comments on "experimental constitutive relations for the high temperature deformation of a PbSn eutectic alloy"

Scripta Metallurgica

Activation energy of superplastic deformation of a microduplex steel by differential temperature tests

Superpastic behavior was studied by mechanically working the cast material to varying degrees. The flow behavior was explored in the temperature range of 298 to 443 K and metallographic observations of longitudinal and transverse sections were made. Due to changes in microstructure and the nonunique stress-strain rate relation, the as-worked material is not suitable for assessing the mechanisms of superplastic flow based on steady state.

Metallurgical transactions. A, Physical metallurgy and materials science

SUPERPLASTIC BEHAVIOR OF THE Sn-Pb EUTECTIC IN THE AS-WORKED STATE.

On the existence of a low strain rate regime during high temperature deformation of a superplastic 25.7% Cr - 6.6% Ni steel

The high temperature steady state deformation behaviour of PbSn eutectic alloy was investigated over wide ranges of grain size (9.7 - 32.0 μm), temperature (298 - 443 K) and strain rate (10-7 - 10-2 s-1), after stability of microstructure and strength had been achieved through prior tensile deformation. The σ-ε{lunate} plots for these materials consisted of regions II and III. In region II the strain rate sensitivity index m is 0.6 ± 0.1 and the grain size exponent p is 3.34 ± 0.23. The activation energy Q in region II was found to depend on temperature with Q = 44.7 ± 1.1 kJ mol-1 below about 408 K and Q = 81.1 ± 3.9 kJ mol-1 above this temperature. These experimental parameters do not agree with any of the superplasticity models that have been proposed to date. However, in region III the parameters m = 0.09 ± 0.01, p = 1.00 ± 0.72 and Q = 100.0 ± 8.8 kJ mol-1 observed are in better agreement with the recovery creep model of Gifkins. © 1981.

Experimental constitutive relations for the high temperature deformation of a PbSn eutectic alloy

Stress-strain rate data of the Pb-Sn eutectic alloy specimens were obtained from differential strain rate and stress relaxation tests. The data were found to differ from each other in the higher temperature range in some cases. This discrepancy could be accounted for in terms of the anelasticity effect on the relaxation behavior by means of the rheological model of H. Schneibel and P. M. Hazzledine. Since the internal stress measurement by the stress dip test may also be affected by the anelasticity, a method of checking whether the internal stress thus measured is a consequence of the anelastic effect or not is proposed on the basis of the rheological model of Schneibel and Hazzledine.