Nadarajan Murugan

Wire arc additive manufacturing is a promising reliable free-form fabrication technique suitable for producing large-scale components that feature a very low buy-to-fly ratio. This research work is aimed to fabricate a rectangular prototype Inconel-625 alloy slab using a robotic metal inert gas welding system. The microstructure and mechanical properties of as-deposited and solution-annealed (SA) alloys were investigated. It was found that the as-deposited alloy exhibited a columnar dendritic structure and the presence of intermetallic phases such as the Laves phase, NbC and carbides were observed in the gamma-nickel matrix. In SA deposit, the intermetallic phases were dissolved in the NiCr-matrix and the secondary carbides M₂₃C₆, M₆C were also observed in the microstructure. It was found that the ultimate tensile strength and microhardness of the as-deposited alloy were higher than that of SA deposit.

The application of artificial neural network (ANN) to predict the wear rate of the surface composites produced using a solid-state technique called friction stir processing (FSP) is presented in this work. The copper surface composites were prepared by incorporating different sort of ceramic particles such as SiC, TiC, Al₂O₃, WC and B₄C. The design of experiments (DOE) strategy was utilised to direct the experimental work. The considered operating parameters were sort of ceramic particle, traverse speed, tool rotational speed and groove width, whereas wear rate is the response. An approximation mechanism having an arbitrary function, the ANN was consequently used for simulating the wear rate of the surface composites. The feedforward back propagation technique was employed to alter the weights of the network to minimise the mean squared error for the development of ANN models. The predicted trends were explained and studied the influence of the considered factors with the aid of observed micro structures. The lower wear rate was observed with B₄C-reinforced surface composites.

Friction stir processing (FSP) was employed to fabricate Aluminium Surface Composites (SC) by reinforcing boron carbide (B₄C) particles with AA6082 aluminium matrix alloy. The role of reinforced particles on the microstructure and mechanical behaviour of the prepared surface composites was studied. The microstructure of the produced composite was examined utilising optical microscopy, scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD). The micrographs of the processed zone revealed fine grains and uniform dissemination of B₄C particles with good interfacial bonding. Microhardness and wear resistance tests were conducted on the matrix alloy, FSPed matrix and produced surfaced composites with the different volume fraction of B₄C particles. The microhardness and wear resistance showed the higher values compared to aluminium matrix and friction stir processed aluminium without B₄C particulates. It was seen that the wear resistance of the FSPed surface composite was improved significantly as compared to that of the AA6082 matrix alloy.