K. Manisekar

Influences of Welding Speed on Tensile Properties of Friction Stir Welded AZ61A Magnesium Alloy

This article reports the influences of welding speed on tensile properties of the friction stir welded AZ61A magnesium alloy. Five different welding speeds ranging from 30 to 150xa0mm/min were used to fabricate the joints. Tensile properties of the joints were evaluated and correlated with the stir zone microstructure and hardness. From this investigation, it is found that the joint fabricated with a welding speed of 90xa0mm/min exhibited the acceptable tensile properties compared to other joints. The formation of fine grains in the stir zone is the main reason for the higher hardness and acceptable tensile properties of these joints.

Influences of tool rotational speed on tensile properties of friction stir welded AZ61A magnesium alloy

This paper investigates the influence of the rotational speed of the tool used in the friction stir welding of an AZ61A magnesium alloy. Five different rotational speeds were used to fabricate joints between plates of the alloy. The tensile properties of the joints were evaluated and correlated with the microstructure observed in the stir zone. The formation of very fine grains in the stir zone is observed to create superior tensile properties for these joints.

Effect of Reinforcement and Tribological Behaviour of AA 7068 Hybrid Composites Manufactured through Powder Metallurgy Techniques

In this article, an attempt was made to study the mechanical behaviour of AA7068 - 6 vol. % of MoS2 - X vol. % of WC (X = 0, 5, 10 and 15) hybrid aluminium composites produced by blend–press–sinter methodology. Compacted Powders (700MPa) were sintered at different temperatures (450 0c, 500 0c and 550 0c ) in order to find the influence of sintering temperature on mechanical properties and tribological behavior of AA7068 hybrid composites.The sintered samples have been characterized by x-ray diffraction (XRD) method for identification of phases and also to investigate the phase changes. The change in density, hardness and porosity values of composites were reported. The composite with 15 vol. % of tungsten carbide and 6 vol. % of MoS2 showed the highest hardness and density at the sintering temperature range of 550 0c. Pin-on-disc type apparatus was used for determining the wear loss occurring at different conditions. The hybridization of the two reinforcements enhanced the wear resistance of the composites, especially under high applied load, sliding distance and sliding speeds. Due to this, the hybrid aluminium composites can be considered as an outstanding material where high strength and wear-resistant components are of major importance, predominantly in the aerospace and automotive engineering sectors. The morphology of the wear debris and the worn out surfaces were analyzed to understand the wear mechanisms.