On the stress- and strain-based fatigue behavior of welded thick-walled nodular cast iron

Abstract

Nodular cast iron (GJS) represents one of the most widely used materials for vehicle, energy and heavy machinery industry. Nevertheless, foundries struggling with the influence of local material defects in GJS like pores, shrinkages and dross often leading to a locally reduced fatigue strength of the entire component. One measure to tackle those negative effects is the welding of the affected areas. This measure is then successful when locally achieved material strengths and surface qualities are higher than the component with the casting defect. Unfortunately, data for the lifetime and fatigue assessment of welded GJS are not present right now. Thus, the research project »nodularWELD« assessed the local stress- and strain-based fatigue data of different thick-walled GJS grades for building a basis for a successful usage even of defect affected components. So, three ferritic and pearlitic GJS grades were investigated in the heat-affected zone, the base material, the welding filler and more over in an integral material state comprising all those three aforementioned states based on axial and bending investigations. Additionally metallographic and fractographic analysis were conducted.