Evaluation and modification of inclusion characteristics in HK40 heatresistant cast steel

In this investigation, specifications of inclusions such as type, morphology, number, composition, size, and place of inclusions in HK40 heat-resistant casting steel were studied by optical microscopy and scanning electron microscopy equipped with energy-dispersive spectroscopy system. Then, the effects of calcium silicide (CaSi) addition on these characteristics were evaluated in two pouring temperatures of 1420°C and 1470°C. Results showed that most of the appeared inclusions were in type of chromium oxide and addition of CaSi had a significant effect on the modification of morphology, size, distribution of inclusions, and changing the composition to oxide-sulfide compounds.