If the molten steel is not deoxidized, the continuous casting billet will not have the correct solidification structure.The high oxygen content in steel can also cause defects such as subcutaneous air bubble and porosity, and aggravate the harmful effect of sulfur.The residual oxide inclusion in the steel will reduce the plasticity, impact toughness and other mechanical properties of the steel. Therefore, the excess oxygen in the steel must be removed.
(1) control the molten steel temperature.
(2) Control (TFe) does not aggregate.
(3) Do not drop the lance easily once a splash occurs during the blowing process.
(4) When the furnace temperature is very high, the slag can be thickened with white ash while carrying the oxygen lance.
(1) Impact of scrap and molten iron on furnace lining and mechanical wear.
(2) Agitation and gas scouring of molten steel and slag.
(3) Chemical erosion of lining by slag.
(4) Cracking and peeling of furnace lining temperature, heat shock and microstructure change
The mass production at home and abroad proves that the implementation of the concentrate policy is an important way to realize the automation of the converter steelmaking process and improve the technical and economic indicators.Reasonable selection of raw materials is based on the level of smelting steel, operation technology and equipment to achieve low input, high quality output.
(1) Concentrate policy, reduce slag.
(2) Rational slagging system
(3) Adopt reasonable oxygen supply system and loading system to reduce mechanical splashing.
(4) Adopt heat compensation technology, eat more scrap steel, reduce chemical burning loss.
(5) Adopt reasonable reblowing technology.
When the amount of lime added to each ton of metal is less than 20kg/t, the metal forming slag per ton is less than 30kg/t, which is a low-slag operation.
(1) The addition of less lime reduces slag and energy consumption and reduces the discharge of pollutants.
(2) High oxygen utilization rate, low end oxygen content, high residual manganese, high alloy yield.
(3) Reduce lining erosion and splash.
To reduce oxide inclusions in steel, foreign inclusions should be minimized.Improve the purity of raw materials;Adopt reasonable smelting process, deoxidizing system and refining process of molten steel according to the requirements of steel types;Improve the quality and performance of resistant materials used in converter and pouring system;Reduce and prevent the secondary oxidation of molten steel, maintain the normal casting temperature, implement the whole protection casting, select the protection slag with good performance;The selection of reasonable steel thermal processing and heat treatment technology is beneficial to improve the properties of inclusions and improve the quality of steel.
The inert gas argon, which is insoluble in molten steel and does not react with any element, is an ideal stirring gas and is therefore widely used.From mixing, nitrogen and argon, and nitrogen gas is cheap, but nitrogen can dissolve in the molten steel at high temperature, the increased nitrogen is on the rise of temperature and blowing nitrogen increased with the extension of time, when the temperature higher than 1575 ℃, can make the nitrogen content in steel increased by 0.003%, affects the quality of the steel, thus is restricted to use nitrogen as the mixing gas, only a small amount of nitrogen steel available nitrogen used as mixing gas, but also exists the problem of the increasing nitrogen.
(1) The carbon in the molten iron is oxidized by decarburization to a range close to or equal to the carbon in the molten steel when the steel is produced.
(2) The CO generated by the circulating stirring of the molten pool is necessary to remove the gas in the steel.
(3) It is conducive to the removal of non-metallic inclusions in steel.
(4) It provides heat source for steelmaking reaction.
(5) It is beneficial to the slag steel reaction during blowing
Slag is the first step in steel making. Almost all steelmaking tasks are related to slag melting.The purpose of steelmaking and slagging is:
(1) Remove harmful elements P and S from steel.
(2)The molten steel slag covers the surface of the liquid steel to protect the liquid steel from excessive oxidation and absorption of harmful gases.
(3) Absorb floating inclusions and reaction products.
(4) Ensure that the carbon and oxygen reactions proceed smoothly.
(5) The lining erosion can be reduced.
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