Among the range of ladle metallurgy, the popularization and development of cored wire technology in the metallurgical industry provide a good example and simple way for the production of cast steel and cast iron to improve the performance of castings by improving the inherent quality of molten steel or molten iron.
1. Strengthen the Final Deoxidation of Molten Steel
Generally, under the conditions of top blowing or bottom blowing of argon, 0.4-0.6kg/t aluminum wire is added to the molten steel according to the different steel types, and the residual aluminum content of the molten steel is maintained at the level of 0.025-0.04%, thereby eliminating the scrap due to the casting pores.
2. The Grains of Steel
① Add barium, titanium, niobium and other nitrogen and carbide forming elements to the molten steel to inhibit the deformation and recrystallization of austenite during hot working, prevent the growth of their grains, and through the process of the strain-induced precipitation of their carbon nitride compounds, to achieve the precipitation strengthening of steel.
② Add a certain amount of aluminum to the steel to form a fine dispersive compound with nitrogen and other elements in the steel, and precipitate at the austenite grain boundary, so as to prevent the growth of the austenite grain during the process of the hot working of the casting.
③Adding rare-earth to the molten steel, while purifying the molten steel, forms a film that can hinder the continued growth of grains, thereby making the grains refined.
3. Modification Treatment of Inclusions in Molten Steel
It uses the method of adding aluminum wire and calcium silicon cored wire (or silicon-aluminum-barium-calcium and gold cored wire) to change the number, size, morphology and distribution of inclusions and improve the strength and performance of steel.
Hot Metal Alloying Treatment
The characteristics of using alloy cored wire for hot metal alloying are: the yield of the added elements is very high; the addition amount is accurate and easy to fine-tune; the total amount of alloy addition is the least.
The characteristics of gray iron inoculation treatment with inoculant cored wire technology are: high alloy yield; accurate control of the addition of inoculant; can achieve flow inoculation and instant inoculation; can eliminate insufficient inoculation and occurrence of inoculation The possibility of adding alloys or inoculants by artificial methods is fundamentally eliminated.
Treatment of Molten Ductile Iron
Desulfurization treatment of high-sulfur molten iron smelted in cupola.
Production practice has proven that: in order to reduce the sulfur content of molten iron from 0.15% to 0.015%, the method of spraying or sprinkling granular calcium carbide on molten iron with calcium carbide cored wire method can completely eliminate the unreacted calcium carbide. The environmental impact can greatly reduce (about 40%) the amount of calcium carbide.
Desulfurization Treatment of Non-high-sulfur Molten Iron Smelted in Cupola, Induction Furnace, or Cupola + Induction Furnace
The use of pure magnesium cored wire, or pure magnesium + calcium carbide alloy cored wire, and high-magnesium alloy cored wire for desulfurization can reduce the sulfur content of molten iron from 0.025-0.030% to 0.005-0.009% Level.
Magnesium Treatment of Molten Iron
Currently, there are three types of cored wires used for the treatment of molten iron and magnesium: cored wires with pure magnesium as core agent, cored wires with metal magnesium + ferrosilicon as core agent (ferro manganese nitride), and multi-component composite high-magnesium alloys. Cored wire of core agent. The most widely used is high magnesium alloy cored wire. Magnesium treatment on the wrapped core wire has the advantages of high alloy yield, stable treatment results, and can eliminate the influence of flue gas on the working environment. Data has proved that as long as the alloy of the cored wire contains 25% magnesium, it can economically outperform the traditional flushing method.
Use Cupola High-sulfur Hot Metal to Produce Large-section Ductile Iron
It uses a high-magnesium alloy cored wire containing an appropriate amount of light rare earth, calcium and other elements to desulfurize and spheroidize molten iron at a temperature of 1330°C, and then use a large amount of silicon and an appropriate amount of magnesium, heavy rare earth, calcium, barium, etc. Element's inoculant cored wire is inoculated, and the slag is removed immediately after casting. Compared with the flushing method, it has the advantages of high and stable product quality; small spheroidization and inoculation and recession; low production cost and good control.