DEPARTMENT OF MECHANICAL ENGINEERING

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The effect of A5TB refiner on the fatigue strength of 6063Al alloy
(2010) Ibitoye, S. A.; Adeleke, A. A.; Oluwole, O. O.; Tiamiyu, A. O.; Ode, E. B
The study focuses on the influence of aluminium titantium boron (ASTB) master alloy on the fatigue behaviour at 6063Al alloy. Cylindrical cast rods of 6063Al containing different proportions of A5TB ranging from 0-0.11 wt% were produced and were machined to conform to a standard fatigue specimen. The test specimens prepared were tested for fatique strength at various stress levels, and results obtained were compared. The resistance to fatique failure was observed to decrease as the stress level increased. It was also noted that irrespective of stress level, the optimum fatique strength was obtained when the A5TB content was about 0.06 wt%. It was found that 6063Al alloy to which A5TB master alloy have been added was most suitable for the design of components meant to operate under cyclic loading at low stresses below about 3.02KN/m2.
The role of forging during inertia friction welding of nickel-base superalloy RR1000
(2011-12) Oluwasegun, K. M.; Adedayo, A. V.; Adeleke, A. A.; Oluwole, O. O.
The dissolution response of y’ phase to thermal and mechanical effects in an inertia friction welded turbine disk nickel base superalloy RR1000 has been investigated. The thermo-chemical affected zone (TMAZ) and heat affected zone (HAZ) microstructures around welds in a commercial PM nickel-based RR1000 superalloy were simulated using a Gleeble thermo-chemical simulation system. Detailed microstructures examination of the simulated TMAZ and HAZ and those present in actual inertial friction welded specimens showed that y’ particles persisted during heating to the welding temperatures, where they reacted in the surrounding y matrix producing liquid film by a eutectic- type reaction. However, it was observed that the compressive strain during the forging stage of welding significantly enhanced resistance to weld liquation cracking of the alloy by strain-assisted rapid isothermal re-solidification of the constitutional liquation products within 150µm of the bond line.