The Fracture Mechanisms of an Austenitic Heat Resisting Steel in Copper Converter Atmosphere

The openings of Copper converter in Sarcheshmeh Copper Complex in Iranis made of a heat resisting austenitic steel (Fe-25Cr-12Ni) and many failures have been reported. Understanding the failure mechanism of the alloy helps to develop better alloys for similar complex environments. Samples of as-cast alloy and those taken from failed ones were examined. Optical Microscopy (OM), X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) have been applied to examine the alloy and oxide scales. Investigations show that microscopic structure and operational conditions are parameters which affect the fracture of the alloy. The existence of SO2 in the environment increases the reaction rate and formation of sulphides comes near the surface and around the grain boundaries. The sulphides decrease the oxidation resistance of the alloy.