Nitridation technique of supersupercritical high-pressure boiler tube billet steel

Abstract

The invention relates to a nitridation technique, particularly a nitridation technique of supersupercritical high-pressure boiler tube billet steel. The nitridation technique comprises the following steps: electric furnace smelting, primary LF (ladle furnace) refinement, VD (vacuum degasser) vacuum degassing and secondary LF refinement, wherein in the electric furnace smelting process, the tapping components and temperature need to be controlled, and stirring with argon is also needed; in the primary LF refinement process, the mass percents of Cr and C need to be controlled; and in the secondary LF refinement process, calcium treatment is needed after the components are adjusted to a proper state, soft argon blowing treatment is performed after the temperature and all the components are adjusted, and the molten steel can be fed to a continuous casting process after the soft argon blowing is finished. In the nitridation technique, the nitrogen content is adjusted respectively by introducing nitrogen as a stirring gas into the ladle in the primary LF refinement process and VD vacuum degassing process and supplementing chromium nitride alloy in the secondary LF refinement process. According to the technique, the nitrogen content can be controlled at 0.030-0.070% by introducing nitrogen and adding chromium nitride in a scientific proportion; and after adding the nitrogen, no quality problems of the casting blank, such as surface pores, subsurface pores and the like, are produced.

Description

technical field [0001] The invention relates to a nitrogen-increasing process, in particular to a nitrogen-increasing process for ultra-supercritical high-pressure boiler tube blank steel. Background technique [0002] The electric power industry is one of the key steel users in China, and the steel products used are of various varieties and specifications. Among them, steel technology for power stations and power systems is a national strategic technology, and its products have extremely high added value, which has a direct and decisive support for the development of the national economy and national defense construction. Therefore, the governments and enterprises of the United States, Europe, Japan and other countries have long-term funded the research and development of thermal power steel technology. [0003] According to China's natural resources and national conditions, for a long period of time in the future, thermal power generation with coal-fired generating units ...

AI Technical Summary

Problems solved by technology

[0007] The technical problem to be solved by the present invention is to provide a nitrogen-increasing process for ultra-supercritical high-pressure boiler billet steel in order to meet the need for nitrogen adjustment in the production of ultra-supercritical high-pressure boiler billet steel using an electric furnace + continuous casting process flow. The process can control the nitrogen content at 0.030-0.070% through the scientific ratio of feeding nitrogen and adding chromium nitride. At the same time, the addition of nitrogen can not cause slab quality problems such as pores on the surface of the slab and subcutaneous bubbles.