The Use of Spheroidal Graphite Cast Irons to Develop Forgeability Criteria Based on Local Strain Measurements

Abstract

An attempt has been made to develop forgeability criteria based on data obtained from local strain measurements. Nodular case iron has been used as the modelling material because its microstructure may be manipulated to contain near-spherical graphite nodules which are suitable for the study of deformation, foregeability, etc. Cracking will occur under certain deformation conditions which may be determined by following the changes in spherulite/nodule shape and habit. Local strain in any area of interest may be determined by measuring the shape change of the previously spherical nodules in terms of an aspect ratio b/a (a = major axis, b = minor axis of the deformed nodules) from specimens sectioned after deformation. A wide variety of forgeabilities can be obtained by changing the microstructure and composition of the matrix.