Fundamentals of High Temperature Processes
Evolution of TiN and Oxide Inclusions in Ti-containing Fe-25Ni-15Cr Alloy during Electroslag Remelting
2020 年 60 巻 8 号 p. 1577-1585
詳細
2020 年 60 巻 8 号 p. 1577-1585
The present study was undertaken to investigate the evolution of inclusions in a Ti-containing Fe-25mass%Ni-15mass%Cr alloy during electroslag remelting (ESR). The effect of slag composition on the inclusions in alloy was studied. The inclusions in both consumable electrode and remelted ingots are mainly 1 to 3 µm in size. The inclusions in consumable electrode are TiN, Al2O3–Ti2O3, Al2O3–Ti2O3 with a surrounded TiN layer. The inclusions in liquid metal pool and remelted ingots are TiN, MgO–Al2O3–Ti2O3 inclusion surrounded by TiN, MgO·Al2O3 inclusions, MgO·Al2O3 inclusions with an outer Ti2O3-rich layer. Increasing TiO2 content in slag has no influence on the types of inclusions in remelted ingots. The original TiN inclusions in consumable electrode cannot be dissociated at the electrode tip during the ESR process. TiN inclusions in remelted ingots mainly generated in liquid metal pool during ESR, and the TiN inclusions formed during the solidification of liquid alloy takes up a small amount fraction. Part of Al2O3–Ti2O3 inclusions in consumable electrode were removed through absorbing them into molten slag, and the remaining Al2O3–Ti2O3 inclusions in the liquid alloy reacted with Mg dissolved from ESR slag to form MgO–Al2O3–Ti2O3 inclusions which served as the nucleation sites for TiN inclusion formation. MgO·Al2O3 inclusions in the remelted ingots precipitated in the liquid metal pool during ESR process. The generation of MgO·Al2O3 inclusions with an outer Ti2O3-rich layer originated from the reaction between soluble titanium in liquid alloy and MgO·Al2O3 inclusion to form an outer Ti2O3-rich layer on unreacted MgO·Al2O3 inclusion core.
