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J. Kandasamy ¹, M. Manzoor Hussain ², S. Rajesham ³

Affiliations
1 Dept. of Mech Engg, MVSR Engg., College, Nadergul, Hyderabad, IN
2 Dept. of Mech Engg, College of Engg., JNTUH, Kukatpally, Hyderabad, IN
3 T.K.R. Engg., College, Meerpet, Saroor Nagar, Hyderabad, IN

Abstract

Experimental investigations conducted on SiC/SiC brazed joints with nickel-tungsten as filler material in active vacuum is presented. Brazing experiments are performed at three different temperatures 1400°C, 1450°C and 1500°C in vacuum (10^-2 m.bar) with a heating rate of 3°C per minute, holding at the peak brazing temperatures for 30 minutes and furnace cooled. The microstructures, leak test and joint strength are observed and analyzed. Microstructures of the brazed joints are examined to know the role of temperature, heating rate, soaking time and brazing atmosphere during the reaction. The joint strength results show that the 1400°C brazing temperature provides better leak proof high strength joints. This is due to the optimum thickness of reaction layer obtained through optimum reaction between the ceramic and the brazing alloy during the reaction.

Keywords

Brazing, SiC/SiC, Microstructures, Mechanical Properties.

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S. V. Narsimha Rao ¹, M. Manzoor Hussain ², S. Rajesham ³

Affiliations
1 MVSR Engineering College, Nadergul – 501510, IN
2 JNTUH CES, Sultanpur, Medak, IN
3 TKR Engineering College, Medbowli, Hyderabad, IN

Abstract

Equal channel angular Pressing (ECAP) is at present one of the most promising technique to produce bulk nanostructured or ultra fine-grained materials .ECAP is a severe plastic deformation process where a material is extruded through a channel that intersect at an angle. As the material crosses the channel's intersection, the material is deformed by simple shear and the billet accumulates deformation. The channel of the die are manufactured with approximately the same cross-section. As the cross-section at the entrance and exit is equal, the billet dimension does not change when the part is extruded.In the present work, AA7075 aluminum alloys are processed through ECAP dies with various channel angles at room temperature. After deformation, all the pressed samples are subjected to microstructure test. The results showed improved grain orientation of the ultra-fine grained aluminum alloy that is developed. The results are compared with the microstructure of pure aluminium billet . This research provides an opportunity to examine the significance of the ECAP process for aluminum alloys on microstructure.

Keywords

ECAP, AA7075, Microstructure.

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J. Kandasamy ¹, M. Govindaraju ², M. Manzoor Hussain ³, S. Rajesham ⁴

Affiliations
1 JNTUH, Dept of Mechanical Engg., M.V.S.R. Engg College, Nadergul, Hyderabad, IN
2 Non Ferrous Materials Technology Development Centre, Kanchanbagh, Hyderabad, IN
3 Dept, of Mechanical Engg., College of Engg., JNTUH, Kukatpally, Hyderabad, IN
4 PRRM Engg. College, Shabad, R.R. District, Andhrapradesh, IN

Abstract

Friction Stir Welding (FSW) is an innovative and promising solid state joining process invented by The Welding Institute (TWI). It is considered to be one of the most significant developments in metal joining technology over the lost two decodes. FSW experiments were conducted on 6mm thick AA6061 and AA7075 aluminum plates by changing the position of the plates on advancing and retreating sides of the joint. Characterisation of the mechanical and metallurgical properties shows a strong influence of the plate positions in the weld joint strength. An in-depth analysis of the results indicates the difference in mechanical and metallurgical properties of the weldments due to the intermetollic compound (IMC) formed, with change in position of plates.

Keywords

FSW, AA6061, AA7075, Plate Position, Mechanical Properties, Macrostructures, Proctography.

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