CN101353753B - Ultra-low carbon high-purity industrial pure iron and manufacturing method thereof - Google Patents

Abstract

The invention discloses an ultra-low-carbon (ULC) high-purity industrial pure iron and a production method thereof. The invention is mainly characterized in that: the ULC high-purity industrial pure iron contains chemical elements in weight percentage as follows: C is less than or equal to 0.008 percent, Si is less than or equal to 0.05 percent, Mn is less than or equal to 0.05 percent, S is lessthan or equal to 0.002 percent, P is less than or equal to 0.005 percent, and Al is less than or equal to 0.055 percent. The materials with the proportions of the above chemical compositions are smelted for dephosphorization and desulfurization in an arc furnace, blown with oxygen for decarbonization by AOD (argon-oxygen decarburization), and desulfurized under high temperature and high alkalinity, and finally cast into steel ingots; therefore, the purity of the steel ingots produced by the method can reach 99.5 to 99.7 percent. The maraging steel trial produced by the pure iron of the invention can reach the best level of the steels in China; the pure iron produced by the method of the invention can also improve the performance of other steels such as 00Ni12Cr5Mo3AlTiVA, and push the research and development of high-purity steels.

Description

A kind of ultra-low carbon high-purity industrial pure iron and manufacture method thereof

Technical field

The present invention relates to field of metallurgy ferrous materials pure iron, belong to the novel low carbon ultra-high purity technically pure iron of metallurgy industry ferrous metallurgy especially.The pure iron of using in particular for high purity Ultra-low carbon, low-sulfur phosphorus, low silicon manganese steel is as maraging steel, high purity Ultralow Carbon Stainless Steel.

Background technology

China adopts GB9971, GB6983 raw materials for production pure iron and technically pure iron at present, generally be used to make electromagnetic component, soft magnetic materials, it is higher also to be useful on manufacturing silicomanganese sulphur phosphorus, generally with converter or converter+external refining manufacturing, have through the manufacturing of AOD stove, all there were production in Taiyuan Iron and Steel Co., Baosteel, Wuhan Iron and Steel Plant, Nanjing steel mill etc. in recent years, also a large amount of abroad imports, but, purity is not high, pure iron impurity element height, chemical Composition Control (wet%): C≤0.025, SiMn≤0.2, S≤0.015, P≤0.015, Cr≤0.2, Ni≤0.2, Cu≤0.15; Level (wet%) in kind: C0.005～0.02, SiMnO.02～0.20, S0.005～0.01, P0.005～0.015, quality in kind purity is lower, and particularly carbon, sulphur, phosphorus are higher, can only be used to make common component.Along with more and more higher to the requirement of Precise Alloy, magnetic elements, most advanced and sophisticated high-tech product is also more and more higher to purity requirement, these pure iron have been not suitable for making high-end product, be not suitable for the starting material of the high clarity maraging steel of production Ultra-low carbon, high strength stainless steel, Premium Features material (non-retentive alloy etc.) usefulness, can not be used for sophisticated technology and high quality component.

Abroad for these high-purity industrial pure irons, Japan uses electrolysis process manufacturing, purity can reach iron-holder 99.9%, but price is too high, is not suitable for the starting material as maraging steel, high-purity stainless steel.The domestic electric elements and the soft magnetic materials of GB9971, GB6983 raw materials for production pure iron and technically pure iron manufacturing of adopting can only be used for low-grade component, can't compare with external material object, and the maraging steel performance of producing with this pure iron is low.China's electrolytic process also of no use is manufactured the throughput of technically pure iron at present.

Summary of the invention

The purpose of this invention is to provide a kind of ultra-low carbon high-purity industrial pure iron and manufacture method thereof, it can improve the purity of technically pure iron, and then improves the performance of steel.

The present invention realizes that the technical scheme of above-mentioned purpose is: a kind of ultra-low carbon high-purity industrial pure iron comprises the chemical element of following weight percent proportioning: C≤0.008%, Si≤0.05%, Mn≤0.05%, S≤0.002%, P≤0.005%, Al≤0.05%.

Preferably, described ultra-low carbon high-purity industrial pure iron comprises the chemical element of following weight percent proportioning: C≤0.006%, Si≤0.03%, S≤0.001%.

Carbon nitrogen forms sosoloid in the technically pure iron, easily separates out under the normal temperature to form carbide and nitride, produces magnetic aging, and the carbon height descends magnetic permeability, rectifys stupid rate and improves, and iron loss increases, the magnetization difficulty; Simultaneously carbon nitrogen forms titanium carbide and titanium nitride in maraging steel (Ni-Co-Mo-Ti), the intensity of reduction steel, influences the plasticity and toughness of steel, and therefore, carbon nitrogen must be controlled lower level; The high inclusion that easily forms of silicomanganese makes the plasticity and toughness reduction of steel as the raw material of high purity steel; Sulphur phosphorus reduces the plasticity and toughness of steel, particularly as the starting material of high-intensity high-tenacity steel, reduces the plasticity and toughness of steel, therefore must limit; Aluminium is the most effective deoxidant element, and control aluminium content will effectively reduce the oxygen level of steel.

The manufacture method of described ultra-low carbon high-purity industrial pure iron comprises following steps:

(1) adopts electric furnace (20 tons of electric furnaces) technology: adopt the electric furnace dephosphorization, guarantee that electric furnace reaches the technical requirements of P; Important is that the electric furnace oxidation thoroughly scratches clean oxidation sludge latter stage, prevents that reduction period from returning P;

Reaction formula:

2[P]+5FeO+4CaO _s＝4CaOP ₂O ₅(s)+5Fe (1)

△G°＝—343000+143.35T(J/mol)

2[P]+5FeO+3CaO _s＝3CaOP ₂O ₅(s)+5Fe (2)

△G°＝—338600+142.05T(J/mol)

(a) oxidation style is smelted;

(b) food ingredient C:0.7-1.0%, P≤0.020%, high-quality hangs down the flat steel of S, P and electrode block is formed, (lime requires selected, and fluorite requires superfine, and add-on is a convention amount);

(c) the molten oxygen phase is taken off the P operation, controlled temperature 1540-1570 ℃, until C≤0.08%P≤0.002%, skim 100%, add slag charge after oxygen blast be warming up to 1650 ℃.This stage process is with existing electric arc furnace smelting technology;

(d) reduction: add lime 15～20Kg/ ton in three batches. batch, fluorite 5～8Kg/ ton. batch; Skim 100% when sulphur≤0.010%, add CaO15～20kg/ ton, CaF ₂1～2kg/ ton, aluminium 1～2.52kg/ ton are made new slag tapping, go into the AOD stove;

(2) AOD smelts: AOD oxygen blast argon mixture gas carbon elimination, and when adding aluminium less than 0.008%, carbon heats up 〉=1680 ℃, add CaO and CaF simultaneously ₂Reduce, when sulphur less than 0.0015%, the tapping;

Oxidation principle: 2[C]+O ₂=2CO

[Si]+O ₂＝(SiO ₂)

Desulfurization principle: 5CaO+2[Al]+3[S]=3 (CaS)+(2CaO.Al ₂O ₃)

(a) oxygen blast carbon elimination process: add CaO20～40kg/ ton in two batches, CaF ₂2～7kg/ ton, aluminium 5～10kg/ ton, its flow of oxygen blast (argon) is: O ₂: Ar ₂=8:2 when carbon reaches below 0.008%, reduces, and temperature is controlled at more than 1680 ℃;

(b) reduction period: pre-deoxidation scratches clean oxidation sludge, adds CaO10～30kg/ ton, CaF ₂About 5～10kg/ ton, 2～4kg/ ton aluminium, Argon stirs, argon flow amount 200～500m ³/ h; Add second batch of reductor (CaO5～10kg/ ton, 2～4kg/ ton left and right sides aluminium), Argon (its flow 200～500m after the pre-deoxidation ³/ h), when sulphur reaches tapping below 0.0015%; If S 〉=0.0015% continues to add about CaO5～10kg/ ton, aluminium 2～4kg/ ton and carries out desulfurization, tap less than 0.0015% up to sulphur;

(c) tapping temperature is greater than 1600 ℃;

(d) teeming temperature: 1590～1610 ℃.

Cast 2.3t ingot, without covering slag, the cap mouth is supplied.

Annotate the Bi Mo demoulding in cold 10 hours.

Preferably, described step (1) (d) in, at reduction period, oxidation sludge scratches clean the floating carbon dust in back, makes C about 1.0%, adds calcium oxide 40-65kg/ ton, fluorite 15～25kg/ ton in batches; Make white slag and keep more than 20 minutes,, skim 100%, make new slag when S≤0.008%, tapping, tapping temperature T 〉=1600 ℃, molten steel is poured the AOD stove into, and reduction period uses the agent of Al bulk deoxidation, with CaO and CaF ₂Reduce,, make new slag tapping when S skims 100% less than 0.006% the time.

The present invention compared with prior art has following beneficial effect:

1, the ultra-low carbon high-purity industrial pure iron of manufacturing of the present invention reaches the level of the low impurity element of Ultra-low carbon, and purity has reached 99.5～99.7%.

2, use this pure iron to make the maraging steel of trial-production reach domestic best level; Use this pure iron to significantly improve the performance such as the 00Ni12Cr5Mo3AlTiVA of other steel, promoted the development and the exploitation of high purity steel.

Embodiment

Embodiment

(1) EAF stove:

Divide 4～6 batches to add lime behind the furnace charge fine melt, oxide treatment is carried out in oxygen blast, and 1560 ℃ of phosphorus of temperature skim 100% less than 0.003%; The reduction: add lime 15～20Kg/ ton in three batches. batch, fluorite 5～8Kg/ ton. batch, aluminium 1～2.5kg/ ton; Skim 100% when sulphur≤0.010%, add the 3rd batch of CaO15～20kg/ ton, CaF ₂1～2kg/ ton and aluminium 1～2.5kg/ ton are made new slag tapping, and 1620 ℃ of tapping temperatures are gone into the AOD stove;

(2) AOD stove:

After converting steel, divide to add two batches of CaO20～40kg/ tons, CaF ₂2～7kg/ ton, aluminium 5～10kg/ ton, its flow of oxygen blast (argon) is: O ₂: 800m ³/ h, Ar200m ³About 800 cubic metres of/h blowing oxygen quantities,, reduce 1720 ℃ of temperature when carbon reaches below 0.008%.

Reduction scratches clean oxidation sludge, pre-deoxidation: add CaO10～30kg/ ton, CaF ₂5～10kg/ ton, aluminium 2～4kg/ ton heats up, and Argon stirs, argon flow amount 480m ³/ h; Add second batch of reductor: CaO5～10kg/ ton, aluminium 2～4kg/ ton, when sulphur less than 0.0015%, the tapping.

Tapping: 1620 ℃ of tapping temperatures, big mouthful of tapping of tapping, slag mixes to dash and helps desulfurization.

Teeming temperature is 1600 ℃.

Test-results: see Table 1, table 2.

Table 1 slag charge add-on (22 tons of molten steel) is annotated: blowing oxygen quantity: cubic meter

The chemical ingredients (Wt%) of table 2 trial-production pure iron

Heat (batch) number

C

Mn

Si

S

P

Al

Ti

Cu

Fe

-1063	0.008	0.04	0.05	0.002	0.005	0.01	0.01	0.06	Surplus
										-1065	0.008	0.01	0.01	0.001	0.003	0.01	0.01	0.06	Surplus
-2833	0.007	0.01	0.03	0.001	0.002	0.04	0.04	0.02	Surplus
										-1163	0.008	0.01	0.01	0.0015	0.002	0.01	0.01	0.06	Surplus
-1165	0.008	0.01	0.01	0.001	0.003	0.01	0.01	0.06	Surplus

Claims (2)

1. the manufacture method of a ultra-low carbon high-purity industrial pure iron is characterized in that comprising following steps:

(1) furnaceman's EAF skill:

(a) oxidation style is smelted;

(b) food ingredient C:0.7-1.0%, P≤0.020%;

(c) the molten oxygen phase is taken off the P operation, and 1560 ℃ of controlled temperature until C≤0.08%P≤0.002%, are skimmed, add slag charge after oxygen blast be warming up to more than 1650 ℃;

(d) reduction;

(2) AOD smelts:

(a) oxygen blast carbon elimination process: add CaO 20～40kg/ ton in two batches, CaF ₂2～7kg/ ton, aluminium 5～10kg/ ton, its flow of oxygen blast or argon is: O ₂: Ar ₂=8: 2, when carbon reaches below 0.008%, to reduce, temperature is controlled at more than 1680 ℃;

(b) reduction period: pre-deoxidation scratches clean oxidation sludge, adds CaO10～30kg/ ton, CaF ₂5～10kg/ ton, 2～4kg/ ton aluminium, Argon stirs, argon flow amount 200～500m ³/ h; Add second batch of reductor CaO5～10kg/ ton, 2～4kg/ ton aluminium, its flow of Argon 200～500m after the pre-deoxidation ³/ h is when sulphur reaches tapping below 0.0015%; If S 〉=0.0015%, continuation add CaO5～10kg/ ton, aluminium 2～4kg/ ton carries out desulfurization, tap less than 0.0015% up to sulphur;

(c) tapping temperature is greater than 1600 ℃;

(d) teeming temperature: 1590～1610 ℃.

2. the manufacture method of ultra-low carbon high-purity industrial pure iron as claimed in claim 1, it is characterized in that: step (1) is middle reduction period (d): oxidation sludge scratches clean the floating carbon dust in back, make C 1.0%, add lime 15～20Kg/ ton in three batches. batch, fluorite 5～8Kg/ ton. batch, aluminium 1～2.5kg/ ton; Make white slag and keep more than 20 minutes,, skim 100%, make new slag when S≤0.008%, tapping, tapping temperature T 〉=1600 ℃, molten steel is poured the AOD stove into.