Assessment of the fatigue strength of thick-walled nodular cast iron with Dross

Abstract Dross in large castings made of nodular cast iron reduces the quasi-static and the fatigue strength of the materials significantly, which causes afford to remove the Dross or to reject the complete component, if a secure assessment of the component’s lifetime cannot be performed. The aim is thus to find appropriate methods to determine the quasi-static and cyclic material behavior of Dross and to set up an assessment concept for components affected by Dross with the help of non-destructive testing. For this purpose, cast blocks made of EN-GJS-400-15 were casted with Dross. These blocks were investigated with different NDT methods to achieve information about the position and the characteristics of Dross present. Afterwards fatigue and tensile specimens were removed from the blocks taken from the Dross and the baseline material, which were tested under strain control to determine the cyclic strain based material behavior. Additionally, all fatigue specimens were investigated concerning their Dross distribution with X-ray computer tomography and partly also with magnetic particle inspection to correlate the NDT and the destructive test results with the forms of Dross detected. Further, a fatigue assessment concept including these research results was developed to assess large cast components with Dross.