Effect of Stirring Mode on Non-Metallic Inclusions in Alloy 825 during Ladle Treatment

• It is well known thatinclusions affect the properties of steels and alloys. Therefore, it is essentialto understand what types of inclusions that exist and how they behave duringthe production. This study has examined the behavior of Al2O3-MgOand TiN inclusions in the melt during the ladle treatment of Ni-based Alloy825. The effects of different directions of electromagnetic stirring (EMS) incombination with different gas flows were investigated based on two dimensionaldeterminations of the inclusion characteristics on a polished surface of themetal samples by using Inca Feature analysis. More specifically, the number,size, composition and morphology of different inclusions were determined byusing SEM in combination with EDS. The results show that the use of EMS in thedownwards direction in combination with a 0.04 m3 min-1gas flow rate promotes a significant removal of Al2O3-MgO and TiN inclusions. Furthermore, the use of an upwards EMSstirring direction promotes a drastical increase of the amount of inclusionshaving an equivalent size smaller than 11.2 µm. Also, the use of both stirringdirections in combination with a 0.02 m3 min-1 gasflow rate promote a ~20% to ~60% removal of Al2O3-MgO and TiN inclusions for most heats. No influence on the composition andmorphology could be seen from the different stirring modes.

Ämnesord

TEKNIK OCH TEKNOLOGIER  -- Materialteknik -- Metallurgi och metalliska material (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Materials Engineering -- Metallurgy and Metallic Materials (hsv//eng)

Nyckelord

Ni-based Alloy 825

ladle treatment

stirring conditions

non-metallic inclusions

Metallurgical process science

Metallurgisk processvetenskap

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