Method for smelting molten steel and adding rear earth by vacuum induction furnace

Abstract

The invention relates to a method for smelting molten steel and adding rear earths by a vacuum induction furnace, comprising the following steps: I, raw material preparation, weighed rear earth wiresare bent into an M shape and distributed on ingot moulds, and then the ingot moulds are arranged in a high-vacuum induction furnace; II, charging, pure iron, ferroalloy or returned scrap steels are charged into a crucible of the vacuum induction furnace, and ferrosilicon and metal manganese are put into a hopper; III, vacuum pumping by closing a furnace cover, vacuum pumping is carried out for 12min to 16 min, and furnace burden is heated by supplying power; IV, furnace burden melting; V, refining, solid raw materials which are charged into the furnace are all melted to form molten steel; VI,inflation, after the refining is finished, vacuum pumping is stopped, and argon gas is charged into a cavity of the vacuum furnace; VII, alloying, under the protective atmosphere of the argon gas, rear earth element composition is regulated; VIII, final deoxidation, Al pills are added to carry out deoxidation; and IX, steel tapping casting, steel liquid is poured into the ingot moulds which are wound by the rear earth wires. The method for smelting the molten steel and adding the rear earths by the vacuum induction furnace has high recovery rate of rear earth elements.

Description

technical field [0001] The invention relates to a method for adding rare earth to molten steel in a vacuum induction furnace. Background technique [0002] In order to meet the needs, rare earth must be added to some steel types, and rare earth is added when the molten steel is smelted in the vacuum induction furnace. There are generally two methods for adding rare earths to molten steel in the existing vacuum induction furnace smelting, one is to add rare earth wires to the molten pool at the end of refining, and the other is to add rare earth ferrosilicon to molten steel at the end of refining. Because rare earth elements react with dissolved oxygen and oxide inclusions in steel under vacuum and in molten steel, if rare earth wires are added to the molten pool at the end of refining, the recovery rate will be reduced due to the reaction of rare earth elements with crucible refractories. The recovery rate is less than 30%, and it is difficult to accurately control the fini...

AI Technical Summary

Problems solved by technology

Because rare earth elements react with dissolved oxygen and oxide inclusions in steel under vacuum and in molten steel, if rare earth wires are added to the molten pool at the end of refining, the recovery rate will be reduced due to the reaction of rare earth elements with crucible refractories. The recovery rate is less than 30%, and it is difficult to accurately control the finished rare earth; if the rare earth ferrosilicon (containing 23.3% rare earth, Si36%) is added to the molten steel at the end of refining, it is easy to increase silicon, which limits its use