Steelmaking method of microalloy steel with added vanadium nitride alloy in steel

Abstract

The invention provides a steelmaking method of microalloy steel with added vanadium nitride alloy in the steel, and the method is characterized in that during steel making, when molten steel poured into a ladle accounts for 20-40% of the steel tapping amount, a packaging block of a vanadium nitride alloy additive which is specially sealed and packaged is thrown into the ladle, and residual moltensteel is poured into the ladle; the vanadium nitride alloy additive is a mixture of vanadium nitride alloy powder and 0-10% of aluminium powder or aluminium particles, and is sealed and packaged intoa packaging block by a packaging bag; the packaging bag comprises an outer layer of paper-based packing paper with sufficient strength, and a lining of a single-layer or double-layer airproof plasticfilm; the vanadium nitride alloy powder is directly prepared by the following steps: mixing vanadium compound powder and carbon powder to obtain a mixed powder raw material, adding the powder raw material into a preparation furnace, introducing ammonia gas or nitrogen into the preparation furnace, and allowing the raw material to perform pre-reduction, carbonization and nitridation reactions. Compared with existing steelmaking methods of microalloy steel, the invention can effectively increase recovery rates of vanadium and nitrogen, and improve steel quality.

Description

technical field [0001] The invention belongs to the technical field of iron and steel metallurgy, and relates to a method for smelting micro-alloyed steel in which vanadium nitride is added. Background technique [0002] In the steelmaking process of microalloyed steel, the vanadium and nitrogen in the microalloyed steel can be increased by adding vanadium nitride (VN) alloy to the steel, thereby improving the performance of the steel. But for a long time, powdered vanadium nitride alloys are considered unsuitable for steelmaking. In the existing process, block VN alloys are generally directly added to the ladle before and after tapping. These bulk VN alloys are usually prepared by adding vanadium oxides such as V 2 o 5 , VO 2 , V 2 o 3 etc. mixed with carbonaceous powder and ground to 120 mesh, then mixed with aqueous solution of binder, briquetted, shaped, dried, and then sent to the preparation furnace. Nitrogen or nitrogen-ammonia mixed gas was introduced into the p...

AI Technical Summary

Problems solved by technology

Steelmaking with this bulk VN alloy product has the following disadvantages: 1. The density of this bulk VN alloy is generally 3.0-4.0g / cm 3 , after being put into molten steel, it will float on the surface of molten steel for a long time, and the melting speed in molten steel is slow, and it is easy to be oxidized to reduce the recovery rate of vanadium and nitrogen; 2. There are a large number of small pores in this block product, and its adsorption The air and water vapor in the high-temperature molten steel interact with VN, which will also reduce the recovery rate of vanadium and nitrogen; 3. The uniformity of the composition of this block product is poor, which makes it difficult to accurately control the amount of its addition in the steel, and in the steel The distribution in the medium is not uniform enough, which makes the mechanical properties of the steel poor and the dispersion is large, and the quality is not stable enough

However, this scheme also has the following disadvantages: a special cored wire manufacturing process is required and a large number of steel strips are used; a wire feeder is required to feed the cored wire into molten steel during steelmaking; the molten steel needs to melt the cored wire first. After the steel outer layer interacts with VN alloy powder, not only the VN alloy enters the molten steel at a slower speed, but also consumes more heat energy to melt the steel outer layer of the cored wire steel; the weight ratio of the outer steel layer of the cored wire Large, high shipping cost