S. Ramesh Kumar

Effect of Processing Routes on Microstructure and Mechanical Properties of 2014 Al Alloy Processed by Equal Channel Angular Pressing

Al-Cu alloy was deformed through equal channel angular pressing (ECAP) by routes A, B(subscript a), B(subscript c) and C up to 5 passes. ECAP was done using a 90o die for three different conditions, namely 1) as received, 2) solutionised at 768 K for 1 h and 3) solutionised at 768 K for 1 h + aged at 468 K for 5 h. The microstructure, microhardness and tensile strength were studied for all the three conditions and four routes. Significant improvement in hardness (HV 184 after five passes) and strength (602 MPa after three passes) was observed in solutionised and aged 2014 Al alloy deformed through route B(subscript c). Microstructure evolution was reasonably equiaxed in route B(subscript c). with aspect ratio of 1.6. Solutionised and aged 2014 Al alloy deformed through route B(subscript c) was identified to have better microstructure and mechanical property than the other processing routes and conditions.

Densification of Al 5083 Mechanically Alloyed Powder by Equal Channel Angular Pressing

Equal channel angular pressing (ECAP), one of the most important methods in SPD, is used for the consolidation of mechanically alloyed Al 5083 powder. This paper mainly focuses on the densification of Al 5083 mechanically alloyed powder by ECAP with and without application of back pressure up to three passes with four different routes at room temperature. Aluminum can is used to encapsulate the powder. The particle size, crystallite size, microstructure and density were evaluated by scanning electron microscope and X-ray diffraction peak profile analysis. The crystallite size was measured by Williamson Hall analysis. Density and hardness were increased with increasing number of passes and upon sintering after ECAP. Good densification as well as good powder bonding was observed after three passes of ECAP.

Equal Channel Angular Pressing of an Aluminium Magnesium Alloy at Room Temperature

Severe plastic deformation affects grain size and its distribution to a great extent and it in turn has an impact on the mechanical properties of the specimen. This paper mainly focuses on the microstructure and mechanical properties of the Al 5083 processed by equal channel angular pressing at room temperature. The grain size, crystallite size and dislocation density were evaluated by transmission electron microscopy and X-ray diffraction peak profile analysis. The crystallite size and dislocation density were calculated by Williamson–Hall plot method. The mechanical properties such as hardness, tensile strength increase as the number of passes increases. Interestingly percentage of elongation also increases as the number of passes increases. The factors responsible for the change in mechanical properties were identified by electron diffraction and discussed.

Comparative analysis of delamination factor prediction using RSM and ANN during endmilling of GFRP composites

Abstract This research work is to study the comparison between a response surface methodology (RSM) and artificial neural network (ANN) in the modelling and prediction of delamination factor during endmilling of glass fibre reinforced polymer (GFRP) composites. Aiming to achieve this goal, several milling experiments were performed with polycrystalline diamond inserts at different machining parameters namely feed rate, cutting speed, depth of cut and fibre orientation angle. Mathematical model is created using central composite face centred second-order in RSM and the adequacy of the model was verified using analysis of variance. ANN model is created using back propagation algorithm. With regard to the machining test, it was observed that feed rate is the dominant parameter that affects the delamination factor followed by the fibre orientation. The comparison results show that models provide accurate prediction of delamination factor in which ANN perform better than RSM. The data predicted from ANN is very nearer to experimental results compared to RSM, therefore we can use this ANN model to determine the delamination factor for various FRP composites and also for various machining parameters.

Modelling of machining force in end milling of GFRP composites using MRA and ANN

Abstract Glass Fibre Reinforced Plastic (GFRP) composites show a tremendous increase in applications due to their superior properties. Some damages on the surface occur due to their complex cutting mechanics in cutting process. Minimization of the machining force is fairly important in terms of product quality. In this study, a GFRP composite material with 15°, 60° and 105° were milled to experimentally minimize the cutting forces on the machined surfaces, using solid carbide end mills with 25°, 35° and 45° helix angles at different combinations of cutting parameters. Experimental results showed that the machining force increased with increasing fibre orientation and feed rate; on the other hand, it was found that the machining force decreased with increasing cutting speed and helix angle of the end mill cutter. In addition, analysis of variance (ANOVA) results clearly revealed that the helix angle of the end mill cutter was the most influential parameter affecting the machining force in end milling of GFRP composites. A model based on an artificial neural network (ANN) is introduced to predict the machining force of GFRP with three different fibre orientations. This model is a feed forward back propagation neural network with a set of machining parameters as its inputs and the machining force as its output. Levenberg–Marquardt learning algorithm was used in predicting the machining force to reduce the number of expensive and time-consuming experiments. The highest performance was obtained by 4-18-18-1 network structure. ANN was notably successful in predicting the damage factor due to higher R2 and lower RMSE and MEP.

Microstructural and Mechanical Characterization of as Weld and Aged Conditions of AA2219 Aluminium Alloy by Gas Tungsten Arc Welding Process

In this article, Welding of AA2219 aluminium alloy using Gas tungsten arc welding process (GTAW) and evaluation of metallurgical, mechanical and corrosion properties of the joints are discussed. The weld samples were subjected to ageing process at the temperature range of 195°C for a period of 5 h to improve the properties. AA2219 aluminium plates of thickness of 25 mm were welded using gas tungsten arc welding (GTAW) process in double V butt joint configuration. The input parameters considered in this work are welding current, voltage and welding speed. Tensile strength and hardness were measured as performance characteristics. The variation in the properties were justified with the help of microstructures. The same procedures were repeated for post weld heat treated samples and a comparison was made between as weld condition and age treated conditions. The post weld heat samples had better tensile strength and hardness values on comparing with the as weld samples. Fracture surface obtained from the tensile tested specimen revealed ductile mode of failure.

Effect of Equal Channel Angular Pressing on Densification Behavior of Al 5083 Alloy Powder

In this present study Al-5083 alloy powders were prepared from elemental powders using high energy ball milling under optimized milling parameters. Various properties such as crystalline size, particle size and morphology have been studied using X-Ray diffraction analysis and Scanning Electron Microscopy. It was found that Al-5083 alloy was formed and nanocrystalline size particles were achieved. These nanocrystalline Al-5083 alloy powders were consolidated using equal channel angular pressing with and without application of back pressure. Physical and mechanical properties such as density and hardness are studied.