The structure and composition of slag shell and final slag during remelting process of 9. 5 t remelting ingot of hot working die steel H13 with 380 kg 60CaF

2

-30Al

2

O

3

-10CaO ternary slag system have been analyzed. Results show that during electroslag remelting process the slag shell presents obvious laminating-structure

from out-side to inner-side in proper order being rapid cooling layer

aluminum oxide precipitating layer and inner remelting layer； the CaF2 content in final slag is generally lower than that in initial slag and the CaF

2

content in lag shell is higher than that in initial slag； the aluminum oxide content in outside of final slag is highest ； and the oxygen content in remelted slag is obviously higher than that in original slag.