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In the upsetting process, flow of metal starts from centre region to outer region and failure occurs due to nucleation of void, growth of void and finally void coalescence into micro-crack. These micro-cracks extend in the hoop direction and fracture occurs at the equatorial region due to the presence of accumulated stresses. Hence, the failure of the components strongly depends on the stress accumulated on the failure zone. In the present work, the failure zone was identified through upsetting experiments on powder metallurgical Al–4 wt% Ti composites that have different initial relative densities and an aspect ratio of 1. It was found that the failure occurs at the equatorial region due to accumulation of maximum principal stresses. These accumulated stresses affect the failure limit of the work piece during cold upsetting. Hence, it is necessary to relieve these accumulated stresses for better failure limit in various engineering applications. Thus, this work is aimed at relieving the accumulated stresses on the failure zone by heating selectively on the region where more work hardening has taken place during the deformation stage. As the heating has been performed only at selected locations, the mechanical properties of the samples are not expected to deteriorate due to the heating step. As a result, initiation and progression of failure can be delayed by selective heating before the onset of failure initiation. Selective heating relieve the accumulated stresses and delay the failure onset, thereby increasing the failure limit of the metal.

In this work, a new method of selective heating is proposed to increase the deformation behaviour of cylindrical sintered aluminium preforms during the process. Initially, cold upsetting is carried out using 0.5 MN hydraulic press machine at 0.1 s−1 strain rate and the failure locations of the preforms are predicted for various initial relative densities with the aspect ratio of 1 during the deformation process. After the prediction of this failure location, various conditions of selective heating are attempted uniformly on the deformed preforms after a certain stage of deformation before the onset of the failure initiation, using portable gas cartridge at a different temperature and time to assess their consequence on formability behaviour. The detailed experimental results are evaluated for the formability of the selectively heated preforms under different variables such as flow stress, relative density, axial strain, formability stress index and stress ratio parameter. As a result, the initiation of failure and its progression can be delayed by selectively heating the samples before the onset of the failure initiation. Selective heating of the failure location may relieve the accumulated stresses and delay the onset of failure to a later strain level thereby increasing the formability of the metal.

Friction stud welding, a recent variant of friction welding process, is ideally suited for naval applications, short-term emergency repairs, submarine rescue, aerospace applications and automotive applications. In all these critical applications, there is a need for joining of dissimilar materials in general and aluminium matrix composites/steel joints in particular as in the case of recent aerospace and automotive applications. The strength of the dissimilar joint is a major concern in all these applications. Due to the variation in thermal properties and inhomogeneous temperature distribution, heat-affected zones are formed that lead to deterioration in strength in the dissimilar joints. In the present work, a new procedure is disclosed that can increase the strength of the dissimilar joint. The design of the specimen is modified and ceramic slurry is introduced at the interface in order to achieve increase in joint efficiency and higher joint strength.

The use of boron carbide-reinforced aluminium matrix composites has grown rapidly in critical applications of aerospace industries, automotive sectors, military, and nuclear engineering. However, boron carbide reinforcement within AA6061 alloy is worthy of investigation in terms of its mechanical and tribological properties. Novel aluminium matrix composites were developed with three different reinforcements (i.e. 5, 10, and 15 wt% of B4C) by using the stir casting process. The developed samples were then tested for performance in terms of mechanical properties (i.e. tensile strength, bending strength, impact strength, shear properties, and micro-hardness). The microstructure of the developed samples was analysed using a scanning electron microscope. By adding 5% B4C reinforcement, the samples display enhanced mechanical properties (high bending, increased resistance to impact test, and shear strength). The micro-hardness tends to increase by increasing the percentage of reinforcement. The novel composites have superior wear resistance due to an increase in the content of B4C particles. The measurements indicate that the wear rate resistance is significantly higher for the composite material with a large amount of B4C particles when was compared with AA6061 alloy. The patterns of surface analysis reveal a homogeneous distribution of ceramic reinforcements in 5 and 15 wt% of B4C samples, as well as a low agglomeration of embedded particles.

The present work investigates the densification and forming limit of sintered porous aluminium–titanium preforms for various relative densities and titanium particles. The compacts of 1 aspect ratio with 2–6% of titanium contents in aluminium matrix for various relative densities were prepared through powder metallurgy route by applying suitable powder forming pressures. A sequence of the cold upsetting test has been carried out using 0.5 MN capacity of hydraulic press machine at 0.1 s−1 strain rate. The relation between true axial strain and preforms relative density was plotted, and the influence of titanium and relative density on the densification curve was investigated at various compaction pressures. The specimen properties like apparent strain hardening exponent (na) and apparent strength coefficient (Ka) was determined through stepwise incremental deformation tests. The critical transition density (CTD) vide forming limit diagram was determined from the plot of na and Ka concerning the preforms relative density, and it was found to be 85.9%, 87.7% and 88% for 2%, 4% and 6% of titanium in the aluminium matrix. The CTD values of porous aluminium–titanium preforms were compared with those of the previous work of porous aluminium–copper preforms under the same compositions. Also, the average grain size of the components was determined and it is observed that 2% of titanium contains a larger grain size compared to other compositions. Hence, a higher forming limit was obtained in 2% of titanium reinforced with aluminium matrix.

Aluminium matrix composites (AMCs) have great potential for critical applications within aerospace, automotive, defence, marine, agriculture and nuclear engineering sectors. The composite materials are very attractive because of their good balance between lightweight versus high strength and machinability. Depending on the particular application, these properties can be further enhanced by adding silicon carbide, boron carbide and graphite, respectively. These reinforcements help to upscale the physical/mechanical properties in order to meet the novel industrial demand. In the present work, a novel hybrid composite is developed through stir cast welding technique. The novel materials manufactured are of great importance, because they exhibit higher mechanical properties and better wear resistance with respect to classical materials (i.e. pure aluminium). The results of mechanical test showed that the addition of 5% boron carbide content to aluminium matrix permits to enhance the tensile properties, shear strength and hardness values; 6% silicon carbide and 4% graphite allow to improve the flexural strength and wear rate, respectively. The best performance was obtained for aluminium composite with 5 wt% boron carbide. The correlation between industrial requirements and the findings from this research indicates that the newly developed composite is an excellent candidate material for structural neutron absorber, armour plate and as a substrate material for computer hard discs.

Friction welding is a solid state joining technique used for joining similar and dissimilar materials with high integrity. This new technique is being successfully applied to the aerospace, automobile, and ship building industries, and is attracting more and more research interest. The quality of Friction Stud Welded joints depends on the frictional heat generated at the interface. Hence, thermal analysis on friction stud welding of stainless steel (AISI 304) and aluminium silicon carbide (AlSiC) combination is carried out in the present work. In this study, numerical simulation is carried out using ANSYS software and the temperature profiles are predicted at various increments of time. The developed numerical model is found to be adequate to predict temperature distribution of friction stud weld aluminium silicon carbide/stainless steel joints.

Owing to high strength to low weight ratio, Aluminium matrix composites are widely used in diverse applications of many industries. This lucrative property is achieved by reinforcing the brittle ceramic particles in the aluminium matrix. Aluminium matrix composites are produced by liquid processing methods and solid processing methods. Nevertheless, liquidprocessing techniques stand out because of its simplicity and its suitability for mass production. In this review article, the production of aluminium matrix composites by different liquid processing technique is discussed and a comparative study is carried out.

Friction welding is the most suitable candidate for joining the dissimilar materials such as AA 6063 T6 alloy/Alumina for critical situations in high temperature and high corrosion resistance applications. In the present work, the numerical simulation was carried out to understand the mechanism of joining of AA 6063 T6 alloy/ Alumina rod by friction welding process. The developed thermo mechanical model is a highly nonlinear due to the interaction between the temperature fields and time dependent of the material properties. The developed numerical tool could be used to predict the temperature distribution, stress, strain and deformation of the dissimilar joints.