Generation Mechanism of TiN Inclusion for GCr15SiMn during Electroslag Remelting Process

TiN inclusion with large size found in ESR ingot is of great harm to steel GCr15SiMn, it is significant to elucidate the possibility of this inclusion in consumable electrode retaining in the subsequent ingot and the effect of slag composition on the content of TiN inclusion in ingot after ESR refining. Based on three remeltings and with the help of ultrahigh-temperature confocal scanning violet laser microscope, it demonstrates that TiN inclusion in electrode will completely decompose in the solid-liquid coexistence region at the electrode tip, reflecting that TiN inclusion found in ESR ingot is regenerated. For different contents of Ti in slag, there is a corresponding equilibrium value of Ti content in steel, when the content of Ti in electrode is higher than this critical equilibrium value, it will decline in steel, otherwise Ti pick-up will occur. The effect of increasing SiO2 content in slag on decreasing Ti content in steel is obvious due to the Si/Ti exchange reaction taking place, further leading to the low content of TiN in ingot.