TO DESIGN THE MOULD AND EVALUATION OF MECHANICAL PROPERTIES OF S S REINFORCED ALUMINIUM ALLOY

Abstract

High strength and low weight are of considerable importance to engineers in most of the mechanical engineering designs as the heavy materials consume more power than light materials. In recent years, weight of the component is important so light weight materials are preferred which have high strength to weight ratio and better mechanical properties. It has created .interest in aluminium base components particularly in aero space applications and automobile industries. The Al-alloy containing Cu, Si, Fe etc. reinforced with stainless steel wires is designed so that it has high strength to weight ratio. Reinforced casting is carried out to fabricate these Metal MatrixComposite (MMC) with an advantage of its simplicity and low cost than other non-conventional methods. A suitable mould is designed to fabricate the reinforced casting in which special care is taken to reinforce stainless steel wires of 0.1 mmo uniformly into the Aluminium alloy and investigations are carried out to know the mechanical properties of Aluminium alloy. The problem under investigation has been introduced in Chapter 1. Chapter 2 is a critical review of theliterature of various non-conventional castings, the design of mould for these castings, mechanism in fibre reinforced metal ncEYix composites(MMCs), the mechanical properties of the ductile fibre and ductile matrix composites and reinforced castings, interface study of the Al-alloy embedded with stainless steel wires, effect of heat-treatment on the strength and on the interface of stainless steelwires embedded in Al-alloy and fractography of the fractured specimens. In chapter 3, a suitable mould which is designed for reinforcing stainless steel wires in Al-alloy is described along with the fabricating procedure and details. Furnace which is constructed for reinforced casting is also describe. The casting procedure is explained. Reinforced castings with different number of stainless steel caries (5, 8 and 15 Numbers) were prepared and heat treated for different extent of time (15 h and 30 h). The mechanical properties are determined by the tensile tests. By metallographic technique, interface studies are carried out by optical microscope. Fr actographic studies are carried out by scanning electron mricroscope (SEM). Chapter 4 deals with the reinforcing response of the stainless steel wires in the aluminium-4.8 weight percent copper alloy, at 5, 8 and 15 number of wires on the mechanical properties. The effect of 15 h and 30 h of heat-treatment at 530°C has also been observed on the reinforced castings with 5,8 and 15 number of wires. It is seen that the ultimate tensile strength is improved with the number of stainless steel wires reinforced in the aluminium-48 weight percent copper alloy. When the heatreatment is increased from 15 h to 30 h, it is observed that the strength is decreasing. Interface thickness increases from 9.451. to 22.24 p when heattreated from the as iv cast condition to 15 h. and becomes 49.984 p after 30 h of heat-treatment. The stainless steel wires have the ultimate tensile strangth (UTS), 700 MN/m2 while the Aluminium alloy matrix has 121 MN/m2. With increase in the reinforced volume fraction of stainless steel wires (i.e. no. of wires 5, 8, and 15), the strength of the composite is increasing. The strength of the composite is higher than the strength calculated from the rule of mixture (from the volume fraction of matrix and the wire). This is because of the very high ultimate tensile strengh (UTS) of the interface region i.e. the intermetallic, Iron Aluminide. With further heat treatment from 15 h to 30 h, the strength fort a particular number of reinforced wires is decreased due to the predominant matrix region which is overaged. The percentage elongation is seen to decrease with the extent of heat-treatment from 15 h to 30 h as the volume fraction of the interface is more and has got negligible ductility. The dictile frac