EFFECT OF ALLOYING ELEMENTS ON THE PROPERTIES OF MALLEABLE IRON CASTINGS

Abstract

The present investigation has been undertaken with a view to ex} lore the possibili.tes of beneficial additions of Nickel. Aluminium, and Tin to malleable cast iron from strength,machinability and corrosion resistance considerations. Mechanical properties tested include tensile, compressive and shear strengths, hardness 'and toughness. The machinability has been evaluated using chip formation as criterion during turning and power consumption during turning and drilling. The corrosion resistance has been evaluated in 5% N p3 and HCl media. Following beneficial facts of alloying elements has been established: I. Improvement In Mechanical properties with optimum addition of 2.5% Ni, and 1% Al. ii. Improvement in toughness with optimum additions of 1.5% Ni, 1% Al and .075% tin. iii. Improvement in machinability with optimum additions of .5% Ni, 1% Al, and .05% tin. iv. Beneficial effects on corrosion resistance in 5% NNO media with optimum addition of .5% Ni. and Al.each and .059 tin. v. The improvement in corrosion resistance in 5% HCl with optimum additions of .2% tin and 2% Ni and Al each. The results have been discussed with reference to metallographic changes brought about by alloying during mallea-bilization. Literature survey has indicated that previously no work has been cone in the above direction. LIT dF TABLES Table No. fescription Pa a 1.1 Engines►ring Properties of Malleable Cast iron 5.6 4.1 Relative Importance of four machinability criterion 37 x.7.1 Alloying Elements and Microstructure 58 4.7.2 Renge and average microstructures of the pre-determinant contituents found in cast Irons 39 4.7.21 Relative tool life of cast iron structure 61 6.1 Composition of Pig Iron 73 6.2 Composition of the base metal 77 6.3 Details about the casting and test specimens 82 7.1 Effect of Ni » addition on the mechanical properties 96 7.2 Effect of N'1- additions on the mac i1 nability properties 97 7.3 Effect of Ni- additions on the corrosion behaviour properties 98 8.1 Effect of Al- addition 3 on the mechanical properties 113 8.2 Effect of A1. additions on the machinabilityr properties 114 8.3 Effect of Al•acditiong on the corrosion behaviour properttos 115 9.1 Effect of tin-additions on the mechanical properties 126 9.2 Effect of tin ""r:fh1 L1op on the machinability properties 127 9.3 Effect of tin. additions or the corrosion behaviour properties 128 (W