Effect of factors including sulfur alloying process and slag series on casting performance of steel GS35C-A (/% : 0. 32 ~0. 39C

≤0. 40Si

0. 50 ~0. 80Mn

≤ 0. 045P

0. 015 ~0. 055S

≥0. 020Al) has been analyzed

and the original LF (sulfur alloying)-RH-calcium treatment process is modified to optimized LF-RH-calcium treatment-sulfur alloying process. Results show that with using calcium treatment after sulfur alloying process

in casting the main nozzle blocking materials are CaS and CaO-Al

2

O

3

-CaS complex inclusions ； as using sulfur alloying after calcium treatment process the number of continuous-continuous casting heats increases from original 2 heats by using calcium treatment after sulfur alloying process to 6 heats; and with using optimized slag series (R 5. 66

~9. 55)

before RH feeding sulfur wire the number of micro-inclusions in steel decreases by 84% as compared with original process

and the number of micro-inclusions at end RH decreases from 9. 09 inclusions /mm

2

to 5. 06 inclusions /mm

2

.