Effect of Al content on non-metallic inclusions in Fe–23Mn–xAl–0.7C lightweight steels

ABSTRACT

The composition, morphology, number, area, size and average distance of inclusions in Fe–23Mn–xAl–0.7C steels were evaluated through an inclusion automatic analysis system (INCA Feature). According to their composition and morphology, six types of inclusions are classified in the present steels: MnS(Se), AlN, Al₂O₃, AlN–MnS(Se), Al₂O₃–MnS(Se), and other inclusions (i.e. Al₂O₃–AlN and MgO–Al₂O₃). Thermodynamic calculation results show that AlN inclusions are formed in molten steel with Al contents of 3.28 and 6.76 wt-%. Irregularly shaped MnS(Se) inclusions precipitate during the solidification processe. AlN and Al₂O₃ generally serve as sites for the heterogeneous nucleation of MnS(Se). Sometimes, AlN particles can precipitate on the surfaces of Al₂O₃ and MnS(Se) inclusions in the solidification process. As the Al content increases to 6.76 wt-%, a large number of agglomerated AlN and AlN–MnS(Se) inclusions are observed. Agglomerated AlN inclusions normally form in the smelting process due to the combined effects of the cavity bridge force and viscous resistance.

KEYWORDS:

• Non-metallic inclusion
• lightweight steel
• AlN inclusion
• MnS inclusion
• high manganese steel
• high aluminium steel
• aggregation behaviour
• average distance

Acknowledgements

This work was supported by the National Natural Science Foundation of China (Grant Nos. 52074199 and U20A20270).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the National Natural Science Foundation of China [grant number 52074199] and [grant number U20A20270].