According the issue of nitrogen content in key steel grades being on the high side at Pangang

by survey and study it is defined that the main factors led to nitrogen being on the high side are the LD end nitrogen content in liquid being on the high side

serious pick-up of nitrogen during tapping and serious pick-up of nitrogen in the process from end refining to tundish

and the key technique to control o£ nitrogen in liquid is put forward including "LD low nitrogen blowing"

"two-step deoxidation to control pick-up of nitrogen in tapping process" and "double argon sealing long nozzle shielding casting" etc. technique

it shall be to control the average LD end nitrogen in liquid no more than 13 x 10

-6

and the average pick-up of nitrogen in liquid du

ring tapping and end refining process to tundish no more than 5 x

10

-6

. Application results show the nitrogen content in finished products of beam steel slab

electrical steel and IF steel is respectively 30.3 x

10

-6

18.2 x

10

-6

and 16.3 x

10

-6

and the average nitrogen content in finished products of heavy rail steel and tire cord steel is respectively 40. 8 x 10-6 and 38.2 x

10

-6

to greatly improve the control level of nitrogen content in low-ni- trogen steel grades at Pangang.