Defect tolerance for castings

Heavy section cast GJS 400 nodular iron was studied. In ultrasonic factory inspection rejected and acceptable material blocks were evaluated by further ultrasonic measurements, radiography and fatigue testing. Radiography was capable to recognize porosity, but the sizes of individual pores could not be assessed. The defected area map of factory inspection resembles the C-scan image produced by semi-manual inspection using BAT method. Fatigue tests show a notable difference in fatigue resistance of the acceptable and rejected materials for 50 % failure probability, but the scatter was clearly higher in the acceptable material batch, meaning that reduction of safe fatigue design curve may be much smaller than the difference at 50 % failure probability