Kazeem O. Sanusi

Microstructure and Mechanical Properties of Ultra-fine Grained Copper Processed by Equal Channel Angular Pressing Technique

The equal channel angular pressing (ECAP) technique is now recognised for achieving very significant grain refinement of ultra-fine grained materials which, at present produce unique mechanical properties. This study reports the results of the tensile tests and the microstructural analysis carried out on the specimens of ultra-fine grained (UFG) copper processed by ECAP technique at room temperature using a die with a 126 o between the die channels. The copper samples used in this work were subjected to six and twelve passes during the ECAP processing. Tensile tests were conducted for samples cut out in two different directions; in the parallel and perpendicular direction at room temperature to evaluate the mechanical properties after the ECAP at these two directions. The microstructural characterization was carried out using optical electron microscope (OEM) and scanning electronic microscope (SEM). The results show ECAP technique introducing significant grain refinement and produced ultrafine grains in copper and there is a potential for achieving high ductility in the copper alloy after processing. The tested sample is characterized by significant differences of strength properties depending on the direction.

The influence of scanning speed and number of scans on the properties of laser formed steel

Laser Beam Forming (LBF) process is an emerging and new forming method that generally requires brute force to forge the steel into the desired shape instead of using conventional methods. This study investigates the changes that occur in low carbon steel through the laser beam forming process. The parameters under investigation include variable scanning speed and number of scans at fixed laser intensity. The effect of these laser parameters on the chemical composition and properties of low carbon steel is assessed through characterisation of both the as received and LBF formed specimens. Characterizations of the laser formed steels were studied using microstructural analysis and micro hardness profiling. The results show that there is a significant increase in the mechanical properties of the LBF formed materials. Scanning power and the number of scans have a noticeable effect on the curvature achieved in the formed samples. The results obtained will contribute towards the further optimization of laser forming methods for steel for the optimization of the properties of steel using Laser Beam Forming process.

The Effects of Microstructural Evolution and Mechanical Behaviour of Unalloyed Medium Carbon Steel (EN8 Steel) After Subsequent Heat Treatment

The effect of microstructural evolution on mechanical properties of unalloyed medium carbon (EN8) steel with emphasis on the effects of grain size within solid phase mixtures and the mechanical response of the material is investigated and reported. Specimens with a range of microstructures (grain size and phase) were prepared by heat treatment. The microstructures were carefully characterized using both optical electronic microscope (OEM) and scanning electron microscope (SEM) and the mechanical properties were studied using tensile and hardness tests. The results indicated that structural parameter that directly controls the yield strength, the ultimate tensile strength and elongation at failure have some influence (direct or indirect) on the stress flow and formability of the material.