Effect of smelting process on inclusions in C- Cr- Ni- Mo stainless steel and its mechanical properties

The effect of two smelting processes (process 1: vacuum induction melting + electroslag remelting and process 2??vacuum induction melting + vacuum arc remelting) on the inclusions in C- Cr- Ni- Mo stainless steel ingot and its mechanical properties were comparatively investigated by means of Aspex Explorer, scanning electron microscopy and EDAX spectrometer. The results show that the mass fraction of gas in the steel ingot casted through process 2 is less than 25??10-6 with irregular shaped Al2O3 inclusions. On the other hand, the mass fraction of gas in the steel ingot casted through process 1 is approximate to 100??10-6 with evenly distributed Cr2O3, Al2O3 inclusions in the size around 5??m. It is obvious that the number of oxide inclusions in ingot casted through process 1 is larger than that in ingot casted through process 2, due to the higher mass fraction of oxygen. Meanwhile, the impact toughness and ductility of specimens sampling from ingot casted through process 1 are clearly lower than those sampling from ingot casted through process 2. Thus, the conclusion could be carefully drawn that taking process 2 could significantly contribute to reducing the mass fraction of gas in steel and improving the cleanliness of steel. Therefore, the higher toughness and ductility of the steel could be obtained.