Investigation on Cutting Force, Flank Wear, and Surface Roughness in Machining of the A356-TiB2/TiC in-situ Composites

1. Introduction

Aluminium matrix composite has high strength, low weight, good wear resistance, excellent formability, high thermal conductivity and low thermal expansion (Chen et al., 2000). These materials successfully applied in centrifugal pumps, control valves, heat exchangers, nozzles and barrel liner for guns (Lewis, 1991). A356 alloy has good castabilty and strength to weight ratio. These properties make them to use in various fields, including torpedoes, missile bodies and automobile components like engine cylinders and pistons. (Amneesh et al., 2016; Shyam Kumar et al., 2015; Srinivasu et al., 2015). TiB₂ and TiC are boride, and carbide-based reinforcements and has superior hardness, stiffness and resistance. These reinforcements will act as good grain refining agents for aluminium alloy (Kennedy & Wyatt, 2000). TiB₂ and TiC reinforcements refine aluminium grains and enhanced the interfacial bonding strength between reinforcements and matrix, which causes improvement in mechanical properties (Birol, 2006).

Machining of the composite material and achieve the geometrical accuracy is a paramount task. Turning is a basic operation is to covert fabricated composites into the desired size and shape (Devinder, 2012; Singh & Singh., 2013). During turning operation, composite material offers variable forces on cutting tool edge. Due to presence of ceramic reinforcement phase, this reinforcement shears the cutting edge and causes the tool wear. This worn-out tool increases an area of contact and spoils the surface texture of a machined surface (Mishra & Sahu, 2014). It is essential to understand the mechanism of chip formation and surface generation and address the challenges associated with the machining of the composites (Hiremath & Auradi, 2016). In-situ composites are attracted many scientists due to its superior mechanical properties. These properties are achieved by reinforcing of small size, dirt and oxide-free reinforcements, which are generated by exothermic chemical reaction. (Tjong and Ma, 2000). Al₂O₃, AlN, TiB₂, TiC, ZrB₂, and Mg₂Si ceramics can be reinforced into aluminium alloys via in-situ synthesis (Pramod et al., 2000). Fabrication of the in-situ reinforcement by reacting with the inorganic halide salts were well documented from the literature. Mahamani, (2011) described that the mechanism of flux assisted synthesis method to fabricate the TiB₂ reinforced composites. The role of the exothermic reaction in developing of high interfacial strength, improved wettability and the cluster-free reinforcement formations are discussed. Dinaharan et al., (2011) synthesized zirconium diboride reinforced composites via K₂ZrF₆-KBF₄ reaction system. Experimental results revealed that the hardness, ultimate tensile strength and wear resistance of composites is improved by an increase in the volume fraction of ZrB₂ particles within the matrix. Mahamani et al., (2015) presented the dual reinforced in-situ composites fabricated through K₂TiF₆-KBF₄-K₂ZrF₆ reaction system. Presence of micro size TiB₂ and sub-micron size ZrB₂ reinforcements in the matrix improved the mechanical properties. Jerome et al., (2010) discussed the synthesis of Al-TiC composites produced by fabricating the composite by reacting with the K₂TiF₆ and graphite with aluminium melt. Analysis of results shows that the addition of reinforcement enhanced the wear performance of aluminum composites.