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2 Advances in Science and Technology. Research Journal

2 2019

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Effect of Natural Aging and Fatigue Crack Propagation Rate on Welded and Non-Welded Aluminum Alloy (AA2219-T87)

Ijaz Mudasir, Qayyum Faisal, Elahi Hassan, Ullah Mudaser, Eugeni Marco, Badshah Saeed, Gaudenzi Paolo

Advances in Science and Technology. Research Journal

2019

Vol. 13, no 3

129--143

Aluminum alloys are widely used for fabrication of aircraft, civil structures, and space vehicles. Fatigue life consideration of a material is the most important design criteria in many such critical applications. In this research work, a widely used Aluminum alloy AA2219-T87 was TIG welded using AA2319 as a filler material. The effect of natural aging on Fatigue Crack Propagation Rate (FCPR) of welded and non-welded compact tension (CT) specimens (AA2219˗T87) is studied. The relationship between stress intensity factor (ΔK) and crack ratio (a/W) for different value of the crack length in base metal and the welded zone is presented. Paris curves for both welded and non-welded specimens and compared to study the effect of natural aging (NA) on FCGR and compared with non-aged specimens. The results obtained provide a base for the development of Structural Health Monitoring systems for the propagation of crack growth in such components.

Effect of Distilled Water and Kerosene as Dielectrics on Machining Rate and Surface Morphology of Al-6061 During Electricdischarge Machining

Arshad Rubab, Mehmood Shahid, Shah Masood, Imran Muhammad, Qayyum Faisal

Advances in Science and Technology. Research Journal

2019

Vol. 13, no 3

162--169

Electric Discharge Machining (EDM) is widely used for manufacturing complex metal parts. The machining parameters like dielectric fluid, electrode material, current, voltage and pulse rate during EDM are controlled to obtain desired Material Removal Rate (MRR) and it also affects the surface morphology of manufactured components. In this research, effect of changing machining parameters, dielectric fluid (distilled water and kerosene) and electrode materials (copper and graphite) on surface morphology of Al 6061 T6 alloy during EDM is investigated. It is observed that the distilled water reacts with the molten aluminum and produces deep pits / voids on the surface due to liberation of hydrogen gas. A micro crack network is seen radiating from the edge of these pits. It is believed that the very high thermal conductivity of distilled water is responsible for the micro crack network and reduced material removal rate when compared with non-reactive kerosene oil.