CN104451385A - Low-carbon low-nitrogen and high-oxygen industrial pure iron and production method thereof - Google Patents

Abstract

The invention discloses low-carbon low-nitrogen and high-oxygen industrial pure iron and a production method thereof. New varieties of the industrial pure iron are designed, and existing EAF+LF+VOD+VHD smelting process equipment is used for producing the industrial pure iron; the tapping C content of an LF (ladle furnace) is more than or equal to 0.25%; because the required carbon content of low-carbon industrial pure iron is less than or equal to 0.09%, ultra low carbon industrial pure iron is not produced, an over-blowing phenomenon cannot occur in a VOD vacuum oxygen blowing process, and factors of returning S in steel can be reduced; [C] and [O] in liquid steel can react with each other by adopting a VOD vacuum oxygen blowing method, so that the content of [N] in the steel can be reduced, and strong deoxidation is not needed in subsequent production of a VHD furnace to ensure that high-oxygen and low-nitrogen industrial pure iron can be produced. The low-carbon low-nitrogen and high-oxygen industrial pure iron disclosed by the invention has the beneficial effects that designed auxiliary materials of the new varieties of the industrial pure iron are suitable for producing ultra-high strength steel varieties such as low-carbon ultra-high strength steel 9310 steel by a vacuum induction furnace, the purity can be improved, the smelting time can also be shortened, and the efficiency can be improved; and the new varieties of the industrial pure iron can be produced by using the existing smelting equipment, so that the cost can be lowered.

Description

A kind of low-carbon (LC), low nitrogen, hyperoxia technically pure iron and production method thereof

Technical field

This is bright relate to produce the low-carbon (LC) of high clarity for vacuum induction furnace, low-gas content steel prepares burden, particularly relate to technically pure iron, the invention still further relates to the production method of the technically pure iron of this high clarity.

Background technology

The current standards iron content of China's technically pure iron is >=99.5%, and below carbon containing≤0.04%, other element is more low better.; Pangang Group Steel Vanadium & Titanium Co., Ltd. adopt converter just smelt iron water be converted into molten steel, ladle refining, vacuum outgas method produce a kind of technically pure iron, its principal character is that chemical component weight per-cent consists of: C≤: 0.03%, patent publication No.: CN101948980A; Baoshan Iron & Steel Co., Ltd adopts the method for electric furnace+AOD to produce a kind of ultra-low carbon high-purity industrial pure iron, and its principal character is the chemical element comprising following weight percent proportioning: C≤0.008%, Si≤0.05%, Mn≤0.05%, S≤0.002%, P≤0.005%, Al≤0.055% patent publication No. CN101353753; Iron and Steel Research Geueral Inst, it is produced and adopts adopting non-vacuum process, utilize hot metal pretreatment-bessemerize-LF refining-billet continuous casting Production Flow Chart to produce the low manganese of a kind of amorphous, low-sulfur raw material pure iron, this pure iron as raw material is characterised in that its weight percent consists of: C:0.03-0.07%, Si:0.10-2.0%, Mn:0.03-0.06%, P :≤0.02%, S :≤0.005%, Al :≤0.02%, Sn≤0.008%, Ti≤0.01%.Patent publication No. CN101041878; Above-mentioned Ultra-low carbon technically pure iron is used for the smelting of ultra low-carbon steel, and low manganese, low-sulfur raw material pure iron sulphur, phosphorus content are high, for gas content not requirement.The common feature of the chemical composition of above-mentioned standard industry pure iron and patent technically pure iron is that carbon content is low, S content is high, and the GN 2 content is high, is not suitable for vacuum induction furnace and produces class super-high strength steel requirement S, the O such as 9310 steel, production that N content is low.

The class super-high strength steels such as 9310 steel produced by external vacuum induction furnace, and general this steel grade or the similar steel grade of using returns steel production, and gas content is lower.Along with the development of ultra pure alloy, require that in alloy, the element sum content such as O, N, S, P all controls 70 × 10 ^-6below or lower level, the special smelting equipment such as existing starting material and vacuum induction furnace can not be satisfied the demand completely.Propose both at home and abroad at present to adopt the mode installing breather, dusting device and extraordinary stirring coil in vacuum induction furnace additional to solve associated materials melting clarity problem, and the ultra pure iron adopting the technology such as vacuum induction, Cold Crucible Melting, electromagnetic levitation-melt, zone-refine, solid electromigration to prepare, production cost is high, cannot be used for vacuum induction furnace batching and use.

The kinds such as current high clarity aircraft engine gear and axle class super-high strength steel 9310 steel, low-carbon (LC), demand content are low, [O]≤15 × 10 ^-6, [N]≤25 × 10 ^-6.Adopt vacuum induction furnace produce such steel can only by the reaction between carbon and oxygen in steel, add the object that strong mixing reaches denitrogenation, because reality batching uses above-mentioned technically pure iron and alloy material, oxygen level is low, nitrogen content is high, such steel carbon content is lower, reaction between carbon and oxygen is restricted, oxygen when vacuum induction furnace is produced, that nitrogen controls difficulty is large, causes that tap to tap time is long, efficiency is low, increases production cost.Therefore research and develop the production of a kind of special technically pure iron for the vacuum induction furnace of the kinds such as super-high strength steel 9310 steel, shorten the heat while the clarity improving steel, raise the efficiency and become the task of top priority.

Summary of the invention

The present invention discloses a kind of low-carbon (LC), low nitrogen, hyperoxia technically pure iron, and object meets dispensing requirements by Composition Control.

The present invention discloses the production method of a kind of low-carbon (LC), low nitrogen, hyperoxia technically pure iron, and object utilizes existing smelting equipment to produce.

The thinking of the present invention program is: design a kind of technically pure iron new variety, utilize existing installation to produce this special technically pure iron, improve oxygen level, reduce nitrogen content raising technically pure iron clarity, enable vacuum induction furnace use this technically pure iron new variety to prepare burden and produce low-carbon (LC) super-high strength steel, shorten the heat while clarity improves, raise the efficiency.

The technical scheme that the present invention's first object realizes: design a kind of high clarity, low-carbon (LC), hyperoxia, low nitrogen technically pure iron new variety:

(1) chemical composition (%):

C≤0.09, Si:0.15 ~ 0.20, Mn≤0.35, S≤0.001, P≤0.006, Ni, Cr, does not limit, Al≤0.030, Ti≤0.015, and all the other are Fe, [O] >=0.0040,

[N]≤0.0040；

(2) clarity index (%): S≤0.001, P≤0.006, Al≤0.030, Ti≤0.015.

The technical scheme that second object of the present invention realizes: a kind of low-carbon (LC), hyperoxia, low nitrogen technical pure

Iron production method, comprises following processing step:

Adopt oxidation style smelting technology, carry out EAF+LF+VOD+VHD smelting by mentioned component, refining rear mold forms steel ingot;

1. eaf process:

Batching: steel scrap, other for the pig iron or return steel composition.

Tapping condition: C >=0.04%, P≤0.003%, temperature >=1630 DEG C;

2. LF technique:

LF puts in place by 0.05% hello Al, adopts silicon carbide, the deoxidation of Al powder, makes white slag, C >=0.25%, and S≤0.002% is tapped, and opening temperature is: 1650 DEG C ~ 1680 DEG C;

3. VOD technique:

VOD puts in place, oxygen blast after thermometric, adds slag charge after stopping oxygen thermometric, and vacuum outgas adds AL2.0 kg/t ~ 4.0kg/t, and vacuum tightness≤100Pa keeps 10min, when S≤0.001% directly hangs out cast, enters LF production treatment S when S >=0.001%.

4. VHD technique:

Be heated to T >=1620 DEG C, add Al powder in right amount depending on Si amount and carry out desulfurization, until hang out cast after S≤0.001%.

5. pour into a mould: adopt argon for protecting pouring.

Thinking of the present invention and innovative point: (1) adopts existing EAF+LF+VOD+VHD smelting technology to equip, LF stove tapping C >=0.25%, due to low-carbon (LC) technically pure iron carbon content≤0.09% required, it not Ultra-low carbon technically pure iron, over-blowing phenomenon is there is not during VOD vacuum oxygen, reduce the factor of returning S in steel, utilize VOD vacuum oxygen method that [C] and [O] in molten steel are reacted, reduce [N] content in steel, follow-up VHD stove is produced not to be needed to carry out strong deoxidation, can produce the technically pure iron of hyperoxia, low nitrogen.(2) in vacuum induction furnace smelting process, carbon has very strong deoxidizing capacity, pressure in vacuum tank during smelting is all at≤5Pa, the deoxidizing capacity of carbon has exceeded many strong deoxidant elements, the oxygen level in molten steel is increased by hyperoxia technically pure iron, make molten steel produce strong carbon boil under vacuo, denitrogenation speed can be accelerated, denitrogenation and deoxidation are carried out simultaneously.

The invention has the beneficial effects as follows: the technically pure iron new variety batching of design is applicable to vacuum induction furnace and produces the super-high strength steel steel grades such as low-carbon (LC) super-high strength steel 9310 steel, shortens the heat, raises the efficiency while clarity improves; Utilize existing smelting equipment to get final product manufacture pure iron new variety, reduce costs.

Embodiment

Embodiment 1 ~ 3

(1) produce three stove high clarity microalloy technically pure irons, chemical composition working control level is as table 1;

Table 1 %

Heat (batch) number	C	Mn	Si	S	P	Ni
							13209122134	0.063	0.03	0.22	0.001	0.0042	0.08
13209122145	0.057	0.04	0.15	0.001	0.004	0.12
							13209101113	0.055	0.05	0.15	0.001	0.004	0.1
Standard-required	≤0.09	≤0.35	0.15～0.25	≤0.001	≤0.006	—

Table 1 continues %

Heat (batch) number	Cr	Al	Ti	O	N
						13209122134	0.11	0.01	≤0.010	40×10 -4	35×10 -4
13209122145	0.33	0.01	≤0.010	53×10 -4	25×10 -4
						13209101113	0.27	0.03	≤0.010	55×10 -4	18×10 -4
Standard-required	—	≤0.03	≤0.015	≥40×10 -4	≤40×10 -4

(2) operational path: EAF+LF+VOD+LF → breaking down cogging → vacuum induction furnace is produced.

(3) process for making:

Embodiment 1

Heat (batch) number: 13209122134

1. eaf process:

Batching: steel scrap 15 tons, the pig iron 16.7 tons, total batch 31.7 tons;

Tapping: C:0.05%, P:0.003%, temperature 1672 DEG C;

2. LF technique:

LF puts in place by 0.05% hello Al, and adopt the deoxidation of SiC, AL powder, keep white slag, C:0.35%, S:0.001% tap, and opening temperature is: 1670 DEG C;

3. VOD technique

Put in place, the oxygen blast of thermometric final vacuum, vacuum outgas adds AL30kg, Si-Ca80kg, vacuum tightness: 1mbar, maintenance 10min, sampling analysis C:0.017%, Si:0.225%, S:0.0015%;

4. VHD technique

Put in place and be heated to 1630 DEG C, add Al grain 10kg, tapping S:0.001%;

5. argon for protecting pouring is adopted, cast Φ 430, Φ 450 electrode bar.

Embodiment 2

Heat (batch) number: 13209122145

1. eaf process:

Batching: steel scrap 15 tons, the pig iron 19.1 tons, total batch 34.1 tons;

Tapping: C:0.03%, P:0.0023%, temperature 1660 DEG C;

2. LF technique:

LF puts in place by 0.05% hello Al, and adopt the deoxidation of SiC, AL powder, keep white slag, C:0.465% S:0.001% taps, and opening temperature is: 1680 DEG C;

3. VOD technique

Put in place, the oxygen blast of thermometric final vacuum, vacuum outgas adds AL30kg, Si-Ca110kg, vacuum tightness: 1mbar, maintenance 10min, sampling analysis C:0.027%, Si:0.18%, S:0.001%;

4. VHD technique

Put in place and be heated to 1623 DEG C, add Si-Ca grain 8kg, tapping S:0.001%;

5. argon for protecting pouring is adopted, cast Φ 430, Φ 450 electrode bar.

Embodiment 3

Heat (batch) number: 13209101113

1. eaf process:

Batching: steel scrap 15 tons, the pig iron 19.1 tons, total batch 34.1 tons;

Tapping: C:0.05%, P:0.002%, temperature 1681 DEG C;

2. LF technique:

LF puts in place by 0.05% hello Al, and adopt the deoxidation of SiC, AL powder, keep white slag, C:0.28% S:0.002% taps, and opening temperature is: 1678 DEG C;

3. VOD technique

Put in place, the oxygen blast of thermometric final vacuum, vacuum outgas adds AL100kg, Si-Ca50kg, vacuum tightness: 1mbar keeps 10min, sampling analysis C:0.012%, Si:0.11%, S:0.0017%;

4. VHD technique

Put in place and be heated to 1618 DEG C, add Al powder 10Kg, Si-Ca grain 30kg, tapping S:0.001%

5. argon for protecting pouring is adopted, cast Φ 430, Φ 450 electrode bar.

Claims (5)

1. low-carbon (LC), low nitrogen, a hyperoxia technically pure iron, is characterized in that: chemical composition (%):

C≤0.09, Si:0.15 ~ 0.20, Mn≤0.35, S≤0.001, P≤0.006, Ni, Cr, does not limit, Al≤0.030, Ti≤0.015, and all the other are Fe, [O] >=0.0040, [N]≤0.0040.

2. a production method for low-carbon (LC), low nitrogen, hyperoxia technically pure iron described in claim 1, is characterized in that: adopt oxidation style smelting technology to carry out EAF+LF+VOD+VHD smelting, refining rear mold forms steel ingot;

Production craft step is as follows:

1. eaf process:

Batching: steel scrap, other for the pig iron or return steel composition;

Tapping condition: C >=0.04%, P≤0.003%, temperature >=1630 DEG C;

2. LF technique:

LF puts in place by 0.05% hello Al, adopts silicon carbide, the deoxidation of Al powder, makes white slag, C >=0.25%, and S≤0.002% is tapped, and opening temperature is: 1650 DEG C ~ 1680 DEG C;

3. VOD technique:

VOD puts in place, oxygen blast after thermometric, adds slag charge after stopping oxygen thermometric, and vacuum outgas adds AL2.0 kg/t ~ 4.0kg/t, and vacuum tightness≤100Pa keeps 10min, when S≤0.001% directly hangs out cast, enters LF production treatment S when S >=0.001%;

4. VHD technique:

Be heated to T >=1620 DEG C, add Al powder in right amount depending on Si amount and carry out desulfurization, until hang out cast after S≤0.001%;

5. pour into a mould: adopt argon for protecting pouring.

3. the production method of low-carbon (LC), low nitrogen, hyperoxia technically pure iron described in a kind of claim 1 according to claim 2, is characterized in that: described production craft step is as follows:

1. eaf process:

Batching: steel scrap 15 tons, the pig iron 16.7 tons, total batch 31.7 tons;

Tapping: C:0.05%, P:0.003%, temperature 1672 DEG C;

2. LF technique:

LF puts in place by 0.05% hello Al, and adopt the deoxidation of SiC, AL powder, keep white slag, C:0.35%, S:0.001% tap, and opening temperature is: 1670 DEG C;

3. VOD technique

Put in place, the oxygen blast of thermometric final vacuum, vacuum outgas adds AL30kg, Si-Ca80kg, vacuum tightness: 1mbar, maintenance 10min, sampling analysis C:0.017%, Si:0.225%, S:0.0015%;

4. VHD technique

Put in place and be heated to 1630 DEG C, add Al grain 10kg, tapping S:0.001%;

5. argon for protecting pouring is adopted, cast Φ 430, Φ 450 electrode bar.

4. the production method of low-carbon (LC), low nitrogen, hyperoxia technically pure iron described in a kind of claim 1 according to claim 2, is characterized in that: described production craft step is as follows:

1. eaf process:

Batching: steel scrap 15 tons, the pig iron 19.1 tons, total batch 34.1 tons;

Tapping: C:0.03%, P:0.0023%, temperature 1660 DEG C;

2. LF technique:

LF puts in place by 0.05% hello Al, and adopt the deoxidation of SiC, AL powder, keep white slag, C:0.465% S:0.001% taps, and opening temperature is: 1680 DEG C;

3. VOD technique

Put in place, the oxygen blast of thermometric final vacuum, vacuum outgas adds AL30kg, Si-Ca110kg, vacuum tightness: 1mbar, maintenance 10min, sampling analysis C:0.027%, Si:0.18%, S:0.001%;

4. VHD technique

Put in place and be heated to 1623 DEG C, add Si-Ca grain 8kg, tapping S:0.001%

5. argon for protecting pouring is adopted, cast Φ 430, Φ 450 electrode bar.

5. the production method of low-carbon (LC), low nitrogen, hyperoxia technically pure iron described in a kind of claim 1 according to claim 2, is characterized in that: described production craft step is as follows:

1. eaf process:

Batching: steel scrap 15 tons, the pig iron 19.1 tons, total batch 34.1 tons;

Tapping: C:0.05%, P:0.002%, temperature 1681 DEG C;

2. LF technique:

LF puts in place by 0.05% hello Al, and adopt the deoxidation of SiC, AL powder, keep white slag, C:0.28% S:0.002% taps, and opening temperature is: 1678 DEG C;

3. VOD technique

Put in place, the oxygen blast of thermometric final vacuum, vacuum outgas adds AL100kg, Si-Ca50kg, vacuum tightness: 1mbar keeps 10min, sampling analysis C:0.012%, Si:0.11%, S:0.0017%;

4. VHD technique

Put in place and be heated to 1618 DEG C, add Al powder 10Kg, Si-Ca grain 30kg, tapping S:0.001%;

5. argon for protecting pouring is adopted, cast Φ 430, Φ 450 electrode bar.