Method for reducing molten steel nitrogen in steelmaking link

Abstract

The invention discloses a method for reducing molten steel nitrogen in a steelmaking link. The method comprises the following steps: controlling combined blowing parameters of a converter, and carrying out phased adjustment; controlling the bottom blowing manner and the flow rate of a steel ladle; adjusting a furnace rear alloying sequence, and adopting a deoxidation principle from weak to strong in sequence; judging whether the converter needs after-blow or not, wherein, for a steel ball of which temperature is increased by blowing oxygen through an RH technology, the converter endpoint temperature is within10 DEG C lower than the lower limit of a key point specified steel tapping temperature, and after-blow warming is not needed; for a steel ball capable of blowing oxygen in the RH technology, the converter endpoint carbon is smaller than or equal to 0.02% higher than aim carbon, and when the temperature reaches a required value, after-blow is not needed. According to the method for reducing molten steel nitrogen in the steelmaking link provided by the invention, by optimizing converter combined blow flow, steel ladle argon bottom blowing and deoxidation alloying sequence and establishing an after-blow principle, under the condition that other technological parameters are not changed, the content of nitrogen in a finished product is averagely reduced by 12 ppm, the performance of steel billets is stably improved, and a larger operation space is provided for a latter process; the method is easy to operate, the cost is not increased, and the practical application effect is good.

Description

technical field [0001] The invention relates to the technical field of steelmaking, in particular to a method for reducing molten steel nitrogen in the steelmaking process. Background technique [0002] With the development of industrial technology, the quality requirements for steel are becoming more and more stringent, especially for the purity of steel. Under certain circumstances, the nitrogen content in steel directly affects the properties of steel materials. Due to the nitrogen content, the formability, welding performance, high temperature toughness and plasticity of steel are reduced, and the aging and cold brittleness of steel are aggravated. On the other hand, nitrogen can also cause cracking of the billet (severe corner cracking). Therefore, it is necessary to control and reduce the nitrogen content of molten steel to avoid problems caused by excessive nitrogen content. [0003] At present, the steelmaking process mainly reduces the nitrogen content of molten s...

AI Technical Summary

Problems solved by technology

[0003] At present, the steelmaking process mainly reduces the nitrogen content of molten steel by avoiding post-blowing, changing the type of re-blowing gas, maintaining the tap hole, and controlling the amount of ore added in the later stage of blowing, but avoiding post-blowing is mainly by improving the model hit rate and the operation level of workers To achieve, in order to reduce the impact of post-blowing on nitrogen, there is no regulation under what circumstances can not post-blowing, therefore, can not directly reduce post-blowing, and then can not reduce the nitrogen absorption of molten steel caused by post-blowing (nitrogen increase by post-blowing at 4- 7ppm); after the type of reblowing gas is determined, the impact on the nitrogen content of molten steel is fixed; in addition, it is difficult to control the amount of ore added in the later stage of blowing, which is affected by many factors such as the condition of molten iron and the end point requirements of steel grades

In fact, it has not really solved the problem of reducing the nitrogen increase in molten steel in the steelmaking process