Abstract
Hadfield steel contains high carbon above 1% manganese content above 11% to stabilise austenite at room temperature while ADI has low manganese content of typically less than 0.4% to suppress the precipitation of carbide during austempering. In ADI austenite is stabilised by dissolving carbon that diffuses from graphite nodules and pearlite (in the case of pearlitic ductile iron). The high silicon in the order of 2.6% promotes graphitisation. The heat treatment procedures for the two materials are also different. However, the resulting matrix of microstructure contains austenite, which is meant to transform to martensite by mechanism believed to be both strain-induced and strain-assisted once the material has been strained. The toughness of Hadfield steel and ADI found to be 90J and 8.3J for respectively. These were below the standard values. Similarly, tensile properties of Hadfield steel i.e. yield strength 338 MPa, UTS 568 MPa and elongation of 20% were all below values of the standard values confirming the inferior quality of the local product.