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             LIFE ENHANCEMENT THROUGH SURFACE ENGINEERING OF

TI-6AL-4V UNDER FRETTING FATIGUE CONDITION

 

Investigators             : Dr. S. Ganesh Sundara Raman and Prof. S. D. Pathak

Sponsoring agency     : MHRD

Value                       : Rs. 10 lakhs

Period                      : 2003 - 2006

Objectives:

(i) To create a dedicated fretting fatigue test facility

(ii)To study the mechanisms of life improvement through surface   modification of Ti-6Al-4V under fretting fatigue loading conditions.

 

EFFECT OF PULSED CURRENT AND ARC OSCILLATION WELDING TECHNIQUES ON THE FATIGUE BEHAVIOR OF TI-6AL-4V AND INCONEL 718 WELDS

 

Investigators         : Dr. S. Ganesh Sundara Raman and Prof. S. D. Pathak

Sponsoring agency : DRDO

Value                   : Rs. 19.96 lakhs

Period                  : 2003 - 2006

Objectives:

(i)               To study the effects of  welding techniques like pulsed current and arc oscillation (separately and in combination) on the welds of two materials -  Ti-6Al-4V and Inconel 718 with respect to

(a) high cycle fatigue life

(b) low cycle fatigue life and

(c) fatigue crack growth characteristics in the short and long crack regimes at low and high stress ratios

 

(ii)              To compare the fatigue behavior of welds produced by the techniques of pulsed current and arc oscillation with that of welds made by continuous current welding without pulsing and arc oscillation

 

(iii)            To compare the fatigue behavior of welds with that of base metal

 

(iv)    To correlate the microstructure of the material with the fatigue behavior.

 

FRETTING FATIGUE BEHAVIOR OF A STRUCTURAL STEEL

Investigators              : Dr. S. Ganesh Sundara Raman

Sponsoring agency      : DST

Value                        : Rs. 7.68 lakhs

Period                       : 2002 - 2005

Objectives:

(1)To design and fabricate an experimental set-up to do fretting fatigue tests on the existing servo-hydraulic testing machine at the Materials Testing Lab., Department of Metallurgical Engineering, IIT Madras. This will help to initiate research work in the area of fretting fatigue at IIT Madras.


(2)To design, fabricate and load-calibrate a Proving Ring to apply fretting on the test specimens through bridge type contact pads.


(3)To get a good understanding of fretting fatigue analyzed from two different perspectives at the same time: Materials Science and Mechanical Engineering.


(4)To find out the effect of fretting on the fatigue life of a structural steel by conducting fatigue tests with and without fretting.


(5)To find out the effect of contact pressure on the fretting fatigue life.


(6)To evaluate the influence of pad span on the fretting fatigue life.


(7)To study the effect of grain size on the fretting fatigue behaviour.


(8)To conduct two-stage tests, i.e., fatigue tests with fretting for a fixed fraction of life and subsequently plain fatigue tests (without fretting) in order to study the effect of fretting.


(9)To describe fretting damage qualitatively and evaluate failure mechanisms through microstructural study employing optical and scanning electron microscopy.


     (10)  To predict fretting fatigue strength/life using already available model(s) and compare with the experimental results.



PRE- AND POST-DEFORMATION STUDIES ON SUPERPLASTICALLY FORMED TI-6AL-4V

       

 

Investigators           : Dr. S. S. Bhattacharya and Dr. S. Ganesh Sundara Raman

Sponsoring agency  : ISRO

Value                      : Rs. 7.16 lakhs

Period                     : 2001 - 2003

Objectives:

a)    To characterize superplastic Ti-6Al-4V in the temperature range of 850-950oC and in the strain rate range of 10-3s-1 to 10-4s-1.



b)    To estimate the ambient temperature tensile properties of the material before and after superplastic deformation.



c)     To perform a qualitative metallographic analysis of the material under different test conditions.



d)    To analyze the mechanical response of the material under the test conditions with a view to understand the operating mechanisms.



e)    To try and predict the change in the mechanical properties, as a rough estimate, in terms of the constitutive equation of flow.





 

 

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