Method for preventing molten steel of high nitrogen steel from spraying

Abstract

The invention relates to a method for preventing molten steel of high nitrogen steel from spraying, and comprises the following steps in order: I pouring molten steel smelted in a converter into a vacuum refining furnace, pumping vacuum, blowing argon at the bottom, and the stirring intensity is that the molten steel in per ton of steel is more than 2L/min; the requirements of the mass percents of C, Si, Mn, P, S, Cr and N in molten steel are as follows: C: 0.25-0.40%; Si: 0.02-0.2%; Mn: 0.06-2.0%; P<=0.018%; S<=0.02%; Cr: 16-22%; N: 0.12-0.8%; II setting vacuum degree 150 mbar-200 mbar, vacuum-pumping time>5 minutes; III setting oxygen lance position>1700 mm, flow <1200 m<3>/h; IV after oxygen blowing, setting vacuum degree valve<2 mbar for more than 10 minutes; V adding lime, fluorite and alloy; VI breaking vacuum and closing bottom argon blowing. The method for preventing molten steel of high nitrogen steel from spraying can prevent molten steel from spraying.

Description

technical field [0001] The invention relates to a method for preventing high nitrogen steel molten steel from splashing. [0002] Background technique [0003] Since stainless steel can be greatly denitrified during vacuum treatment, more and more steel mills use cheap nitrogen instead of argon. By using this method, the nitrogen content of the molten steel can be greatly increased, and the highest nitrogen content can reach 7000ppm , which greatly saves expensive argon, but with the increase of nitrogen usage, the nitrogen content of molten steel at the destination also increases. After the nitrogen content of molten steel increases, there will be a large amount of outgassing during the vacuum treatment process. This process Molten steel will splash, resulting in vicious production accidents such as aluminum cap burn-through, bottom-blown argon tube blown, and ladle stained with slag. Vacuum refining furnace is a kind of airtight furnace, and it is often impossible to det...

AI Technical Summary

Problems solved by technology

[0003] Since stainless steel can be greatly denitrified during vacuum treatment, more and more steel mills use cheap nitrogen instead of argon. By using this method, the nitrogen content of the molten steel can be greatly increased, and the highest nitrogen content can reach 7000ppm , which greatly saves expensive argon, but with the increase of nitrogen usage, the nitrogen content of molten steel at the destination also increases. After the nitrogen content of molten steel increases, there will be a large amount of outgassing during the vacuum treatment process. This process Molten steel will splash, resulting in vicious production accidents such as burning through the aluminum cap, blowing the bottom blowing argon tube, and slag on the ladle.

Vacuum refining furnace is a kind of airtight furnace, and it is often impossible to detect the splash of molten steel in time. The existing method to prevent the splash of molten steel from high nitrogen steel is to analyze the splash of molten steel, and basically determine that the splash of molten steel occurs at the point where the gun is lowered. At this time, due to the superimposition of the three functions of molten steel degassing, carbon-oxygen reaction and vacuuming, molten steel splashes. By adjusting the production process parameters of each stage, the above reactions are carried out separately, so as to avoid the malignant production accident of molten steel spraying. However, the three parameters are difficult to choose reasonably, and the anti-splash effect is poor