CN102051529B - Carbon steel and preparation method thereof - Google Patents
Carbon steel and preparation method thereof Download PDFInfo
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Abstract
The invention provides carbon steel and a preparation method thereof. The preparation method is as follows: primarily smelting liquid steel; tapping to a steel ladle when the content of C in the liquid steel is between 0.05% and 0.10%, the content of P in the liquid steel is not more than 0.015% and the content of S in the liquid steel is not more than 0.020%; during the process of tapping, regulating the content of Si in the liquid steel to 0.17%-0.37%, regulating the content of Mn in the liquid steel to 0.70%-1.00% and regulating the content of oxygen in the liquid steel to less than 0.0020%; controlling the content of Als in the liquid steel to 0.02%-0.03%, wherein the Als represents acid-soluble aluminium; regulating the content of oxygen in the liquid steel to 0.0010% below in a steel ladle refining furnace, and regulating the content of the C in the liquid steel to 0.17%-0.23%; and carrying out circulation vacuum degassing on the liquid steel and regulating the content of Ti in the liquid steel to 0.006%-0.010%, thereby obtaining the carbon steel which comprises the following components by weight percent: 0.17%-0.23% of C, 0.17%-0.37% of Si, 0.70%-1.00% of Mn, 0.006%-0.010% of Ti, 0.008%-0.015% of Als and the balance of Fe and inevitable impurities.
Description
Technical field
The present invention relates to a kind of carbon steel and method of manufacture thereof, particularly a kind of carbon steel and method of manufacture thereof that can be used for high-duty boiler.
Background technology
The 20MnG steel is a kind of carbon constructional quality steel among the CNS GB5310-2008 (seamless steel tubes and pipes for high pressure boiler), and the chemical composition of the SA-210C steel in its chemical composition and the ASTM/ASME technical specifications is basic identical.GB5310-2008 regulation 20MnG steel comprises 0.17%～0.23% C, 0.17%～0.37% Si, 0.70%～1.00% Mn by weight, be not more than 0.025% P, be not more than 0.015% S, be not more than 0.20% Cu, be not more than 0.25% Cr, be not more than 0.25% Ni, be not more than 0.15% Mo and be not more than 0.08% V.
Recent research shows that the Al content of control boiler steel is the key that boiler steel is produced in very low scope, and its reason is that mainly Al content height can cause the cold worked lumber recovery in rear portion extremely low.Yet generally, Al is an alloying element important in the steel.The effect of Al at first is presented as the final deoxygenation that is used for molten steel, can make the molten steel equilibrium oxygen be in lower level, avoids the appearance of high-oxygen steel; Secondly Al is again important thin brilliant element, can improve the obdurability of steel; Al also can be used to fixed nitrogen (N) in addition.The add-on of Al that embodies above-mentioned effect is generally more than 0.020%.
In existing boiler steel smelting technology, in steel, lack under the situation of enough Al, can adopt the refining of LF stove or LF stove refining+vacuum treated method to avoid high-oxygen steel, can adopt the crystal grain of controlled rolling method of temperature refinement steel.Yet prior art is not considered can occur the hazardness of the free N of part in the steel because of lacking enough Al all the time.
Even adopt bof process to smelt steel, also residual in the steel have 0.004%～0.006% nitrogen (the electric furnace flow process is higher).This part nitrogen is used the Al administration of fixed, otherwise nitrogen can be present in the form of free state in the steel, and it is ageing to increase steel, reduces impact resistance, and serious also can cause the steel premature failure.
In sum, in the production technology of existing 20MnG steel, should take low Alt (full aluminium) route; Yet low excessively Alt can cause and have a certain amount of free nitrogen in the steel, and it is ageing to increase steel, reduces impact resistance, and serious also can cause the steel premature failure.
Summary of the invention
The invention provides a kind of carbon steel and method of manufacture thereof, thereby overcome the one or more technical problems in the above-mentioned technical problem.
Comprise 0.17%～0.23% C, 0.17%～0.37% Si, 0.70%～1.00% Mn, 0.006%～0.010% Ti, 0.008%～0.015% Als by weight according to carbon steel of the present invention; Surplus is Fe and unavoidable impurities, and wherein Als representes the molten aluminium of acid.
Unavoidable impurities can comprise and is not more than 0.20% Cu, is not more than 0.25% Cr, is not more than 0.25% Ni, is not more than 0.15% Mo, is not more than 0.007% N, is not more than 0.025% P and is not more than 0.015% S in the carbon steel.
The Ti content of carbon steel and Als content sum can be not less than 0.018%.
Method of manufacture according to carbon steel of the present invention may further comprise the steps: (a) first steel-making water; (b) be 0.05%～0.10% at the C of molten steel content, P content is not more than 0.015%, and S content is not more than at 0.020% o'clock, taps to ladle; (c) in tapping process, the Si content of adjustment molten steel is 0.17%～0.37%, and Mn content is 0.70%～1.00%, and the oxygen level of adjustment molten steel is below 0.0020%; (d) the Als content of control molten steel is 0.02%～0.03%, and Als representes the molten aluminium of acid; (e) oxygen level of in ladle refining furnace, adjusting molten steel is below 0.0010%, and the C content of adjustment molten steel is 0.17%～0.23%; (f) molten steel being carried out the circulating vacuum degassing handles; And the Ti content of adjustment molten steel is 0.006%～0.010%; Thereby obtain carbon steel; This carbon steel comprises 0.17%～0.23% C, 0.17%～0.37% Si, 0.70%～1.00% Mn, 0.006%～0.010% Ti, 0.008%～0.015% Als, and surplus is Fe and unavoidable impurities, and the content of each element is weight percent content in the carbon steel.
In step (a), can adopt converter to come steel-making water just.
The oxygen level that in step (c), can adopt at least a adjustment molten steel in aluminium ferromanganese, ferro-aluminum, ferrosilicon, manganese metal and the low carbon ferromanganese is below 0.0020%.
In step (c), can adopt ferrosilicon to control the Si content of molten steel, can adopt at least a Mn content of controlling molten steel in manganese metal, aluminium ferromanganese and the low carbon ferromanganese.
In step (d), can add the Al content that aluminium is controlled molten steel to molten steel.
In step (e), can adopt CaC
2Or CaC
2With the oxygen level of the combination of aluminium adjustment molten steel below 0.0010%.
Step (a) can be included in the interior smelting molten iron of converter and obtain molten steel, in step (e), can adopt CaC
2The adjustment molten steel oxygen level below 0.0010%, CaC
2Usage quantity (kg) can be molten iron add-on (ton) * 95% * (1.8～2.2) * (0.7～1.0).
Can be in step (e) through adjust the C content of molten steel to molten steel feeding carbon.
Molten steel is carried out circulating vacuum degassing processed steps can be included in and in the RH vacuum unit molten steel is carried out the circulating vacuum degassing and handle, be not more than at pressure that the vacuum treated time can be no less than 10 minutes under the condition of 300Pa.
The step of Ti content of adjustment molten steel can comprise ferro-titanium is added molten steel.
This method of manufacture also can be included in step (f) and afterwards molten steel carried out continuous casting, and the temperature that continuous casting is operated the molten steel in the employed tundish is 1530 ℃～1555 ℃.
According to carbon steel of the present invention and method of manufacture thereof, N in the steel is fixing by fully, promptly can avoid the existence of free nitrogen effectively, thus ageing when having reduced and prevented the reduction of impact resistance as boiler steel.In addition, carbon steel of the present invention has very low Als or Alt, can the cold working at rear portion not had a negative impact.
Embodiment
Comprise 0.17%～0.23% C, 0.17%～0.37% Si, 0.70%～1.00% Mn, 0.006%～0.010% Ti and 0.008%～0.015% Als (aluminium is dissolved in acid) by weight percentage according to carbon steel of the present invention, surplus is Fe and unavoidable impurities.The content of all components that relates in this manual, is weight percent content.
Can comprise according to unavoidable impurities in the carbon steel of the present invention and to be not more than 0.025% P, to be not more than 0.015% S, to be not more than 0.007% N, to be not more than 0.20% Cu, to be not more than 0.25% Cr, to be not more than 0.25% Ni, to be not more than 0.15% Mo.
N is the harmful element in the steel.Ti fixes the N in the steel through forming titanium nitride (TiN) with N.If Ti content is less than 0.006%, then steel intermediate gap nitrogen-atoms is fixed fully inadequately, and because Ti content uses the Als of too high levels to fix N (of the back literary composition) very little, can increase the cold worked difficulty in rear portion of steel in this case.If Ti content more than 0.010%, then can produce the TiN inclusion of bulk, thus the fatigue property of reduction steel.Therefore, carbon steel of the present invention comprises 0.006%～0.010% Ti.
Aluminium in the steel is divided into two types.A kind of is to have little time to float to the deoxidation products Al in the slag when smelting
2O
3In aluminium because Al
2O
3Can not be dissolved in the acid, so will combine to form Al with oxygen
2O
3Aluminium be called sour insoluble aluminium.Another kind is to be mainly contained the aluminium in pure aluminum and the aluminium nitride AlN (AlN) by sour dissolved aluminium, and it is called acid and dissolves aluminium, usually with " Als " expression.Molten aluminium of acid and sour insoluble aluminium sum are called full aluminium in the steel, usually with " Al " or " Alt " expression.General molten steel is through after the refining, and having among the Alt more than 90% is Als, and perhaps Als content approximates Alt content.The alleged acid of the present invention dissolves that aluminium refers to be present in as stated in the steel can be by sour dissolved aluminium (Als), the related statement that the amount of aluminium is dissolved in acid refer to above-mentioned can be by the amount of sour dissolved aluminium element.
In the smelting process of steel, add aluminium as deoxidant element.In addition, aluminium fixes the N in the steel through forming AlN with N.If Als content less than 0.008%, then uses the Ti of too high levels to fix N because Als content is too little, be easy to produce the TiN inclusion of bulk.If Als content, then can increase the cold worked difficulty in rear portion of steel more than 0.015%.Therefore, carbon steel of the present invention comprises 0.008%～0.015% Als.
Bof process is smelted steel, passes through vacuum outgas (for example, RH vacuum outgas or VD vacuum outgas) again, can N content in the steel be controlled at below 0.006%, and only a few surpasses 0.006%, but also can not surpass 0.007%.In carbon steel of the present invention, 0.006%～0.010% Ti and 0.008%～0.015% Als be the N of this content in the steel fully fixedly.Preferably, in carbon steel of the present invention, Ti content and Als content sum are not less than 0.018%, the content summation be not less than 0.018% Ti and Als can be more fully the fixing N of this content in the steel, thereby reduce the ageing of steel to greatest extent.
The method of manufacture of carbon steel of the present invention comprises steel-making water, LF stove (ladle refining furnace) refined molten steel and RH vacuum outgas (the circulating vacuum degassing) just.
At first, in converter, add molten iron, utilize the function of Converter Oxigen Blowing decarburization, molten iron just is smelt molten steel.When molten steel just refines C content is 0.05%～0.10%, and P content is not more than 0.015%, and S content is not more than at 0.020% o'clock, taps to ladle.
In tapping process, can add pre-deoxidant and alloying material to ladle, the oxygen level of molten steel is removed to below 0.0020%, control Si content is 0.17%～0.37%, control Mn content is 0.70%～1.00%.Pre-deoxidant can comprise aluminium matter pre-deoxidant.Aluminium matter pre-deoxidant can comprise at least a among aluminium ferromanganese FeAlMn, the ferro-aluminum FeAl etc.Alloying material can comprise at least a in ferrosilicon (FeSi), aluminium ferromanganese, manganese metal and the low carbon ferromanganese.In addition, the Si in the alloying material, Mn also have the effect of deoxidation.Deoxidation mode in this step is the bulk deoxidation mode, and promptly the oxygen in the molten steel and the Al that added, Si and Mn generate the oxide compound that is insoluble to molten steel or composite oxides and separate out, and float in the slag on the deoxidation products that generates then.
Then, with aluminium (for example aluminum steel) feeding molten steel, the Als content of control steel is 0.02%～0.03%.Here, control Als content is 0.02%～0.03%, considers that rear portion refining procedure, RH vacuum outgas and optional continuous casting steel machine operation all possibly exist Als to change into Al
2O
3Phenomenon.Find that through further investigation if just in the refining process Als content is being controlled to 0.02%～0.03%, the Als content that then can guarantee the cooled strand of continuous casting is in 0.008%～0.015% scope.
Afterwards, adopt the LF stove under the condition of Argon, to carry out liquid steel refining.Specifically, can at first add CaC as reductor
2Or CaC
2Combination with aluminium (for example Al ball) begins electrically heated then.In refining process, because CaC
2And the proportion of aluminium (for example Al ball) is less than the proportion of molten steel, so reductor (that is CaC, that adds
2Or CaC
2Combination with aluminium) mainly is present in the slag and sloughs the oxygen in the slag.Because the oxygen level of slag less than the oxygen level of molten steel, so the oxygen in the molten steel is delivered in the slag, is removed by the reductor in the slag then, this deoxidation mode is called the diffusive deoxidation mode.Electrically heated in the refining process has guaranteed the molten state of slag, plays a role thereby be convenient to reductor.
Reductor CaC
2Or CaC
2Be as the criterion below 0.0010% with the oxygen level in the control molten steel with the add-on of the combination of aluminium (for example Al ball).
CaC
2Deoxidation products comprise CO gas, can make furnace gas also have certain reductibility, can make simultaneously the slag foaming, help the heating of LF stove submerged arc, reduce the possibility that molten steel absorbs airborne nitrogen.Therefore, the present invention preferably uses CaC separately
2As reductor.Using CaC separately
2Content is under the situation of calcium carbide as reductor more than 70%, and the add-on of calcium carbide (unit is kg) can be molten iron add-on (tonnage) * 95% * (1.8～2.2), to guarantee the Control for Oxygen Content in the molten steel below 0.0010%.
When ladle is tapped, can bring a certain amount of converter slag inevitably in converter in ladle.The converter slag phosphorus content is high, and under the effect of LF stove reducing atmosphere, a part of phosphorus in the slag is got back in the molten steel once more, and the P element is slightly increased.Yet, be not more than 0.015% because when the converter smelting molten steel, P content is controlled to, so, can not surpass 0.025% although P content slightly increases.
In refining process, can remove the S in the molten steel significantly.This is because the CaC in the reductor
2Make slag that good reductibility arranged, and increase the CaO content in the slag, so FeS in molten steel and the slag and CaO reaction generate CaS and remove significantly.
The temperature of molten steel is confirmed by the liquidus temperature of steel in the liquid steel refining process.The liquidus temperature of carbon steel of the present invention is 1504 ℃～1514 ℃.Method of manufacture at carbon steel of the present invention comprises that the temperature of molten steel is the loss temperature (for example 30～40 ℃) of liquidus temperature+RH vacuum outgas in the refining process under the situation of steel-making water, LF stove refined molten steel and RH vacuum outgas just.Comprise in the method for manufacture of carbon steel of the present invention under the situation of just steel-making water, LF stove refined molten steel, RH vacuum outgas and continuous casting that the temperature of molten steel is temperature loss (for example 40～50 ℃)+tundish superheating temperature (for example 20～35 ℃) of loss temperature (for example 30～40 ℃)+ladle of liquidus temperature or the temperature+RH vacuum outgas slightly higher than liquidus temperature to tundish in the refining process.
After heating finishes, carbon is fed molten steel, the C content of adjustment molten steel is 0.17%～0.23%.In one embodiment, adopt feeding wire machine feeding carbon cored-wire to adjust the C content of molten steel.
Then, molten steel is carried out the RH vacuum outgas handle, the main effect that the RH vacuum outgas is handled is the hydrogen in the steel is removed to lower level.Specifically, can in the RH vacuum unit, carry out vacuum-treat to molten steel, the treatment time that is not more than 300Pa vacuum treated total time with pressure was as the criterion more than 10 minutes.
In the process that the RH vacuum outgas is handled, the Ti content of adjustment molten steel makes that the Ti content in the molten steel is 0.006%～0.010%.For example, ferrotianium (FeTi) alloy is added molten steel and adjust Ti content.Preferably, make Ti content and Als content sum be not less than 0.018%.
The impurity element that possibly comprise in the carbon steel of the present invention (or being called residual element) Cu, Cr, Ni, Mo can not remove from molten steel through above-mentioned first steel-making water, LF stove refined molten steel and RH vacuum outgas.Therefore, can control the content of these elements in the carbon steel of the present invention through the content of these impurity elements in the control raw material (being molten iron).
According to the method for manufacture of carbon steel of the present invention, through smelting molten steel in converter, handle through LF stove refining and RH vacuum outgas again, can N content in the steel be controlled at below 0.007%.For example, at least a mode in can be in the following manner is controlled at N content in the steel below 0.007%: in the process of bessemerizing, carry out bottom blowing with Ar gas all the time; Change bottom blown gas into Ar gas by nitrogen bessemerizing the later stage; In LF stove refining process, make the slag foamed, avoid the direct and airborne nitrogen of air contact ionization of electric arc.
Pass through aforesaid method; Obtain carbon steel of the present invention; It comprises 0.17%～0.23% C, 0.17%～0.37% Si, 0.70%～1.00% Mn, 0.006%～0.010% Ti and 0.008%～0.015% Als by weight, and surplus is Fe and unavoidable impurities.The unavoidable impurities of this carbon steel can comprise and is not more than 0.025% P, is not more than 0.015% S, is not more than 0.007% N, is not more than 0.20% Cu, is not more than 0.25% Cr, is not more than 0.25% Ni, is not more than 0.15% Mo.
According to the method for manufacture of carbon steel of the present invention, only in the first refining process of molten steel, add aluminium as pre-deoxidant, in the refined molten steel at rear portion and RH vacuum outgas, can not add aluminium, so deoxidation products Al
2O
3Ascent time is long, is easy to produce Al
2O
3Poor high quality steel.
The step that also can comprise continuous casting according to the method for manufacture of carbon steel of the present invention.That is to say, after the RH vacuum outgas is handled, can cast continuously molten steel.The liquidus temperature of carbon steel of the present invention is 1504 ℃～1514 ℃, and the temperature of continuous casting tundish is controlled at 1530 ℃～1555 ℃, and this TR can realize through the electrically heated of front LF stove.The temperature of tundish molten steel is controlled at 1530 ℃～1555 ℃, can guarantees molten steel all casting completion under the low overheat condition.
Further specify carbon steel of the present invention and method of manufacture thereof below in conjunction with example.
Example 1:
In nominal capacity is the converter of 120 tons (actual tap is 120 tons～140 tons), add 140 tons of molten iron, utilize the function of Converter Oxigen Blowing decarburization that molten iron just is smelt molten steel.When molten steel just refines C content is 0.08%, and P content is 0.015%, and S content is 0.010%, and Si content is 0.01%, and Mn content is 0.05% o'clock, begins to tap to ladle.The amount of the molten steel after converter smelting is accomplished is 133 tons.
In tapping process; Add and can the molten steel oxygen level be removed to FeAl (aluminium content is 40%, and all the other the are Fe) 350kg below 0.0020% to ladle, and FeSi (Si content is 73%; All the other are Fe; The Si recovery is 80%) 550kg and metal M n (Mn content is 98%, and all the other are Fe, and the Mn recovery is 92%) 990kg.After adding, using apparatus for determination of oxygen to record molten steel actual oxygen content is 0.0015%, and Si and Mn content are increased to 0.25% and 0.72% respectively in the molten steel.Then, with the Al line 30kg feeding molten steel of feeding wire machine with φ 10mm, the Als content of control molten steel is 0.03%.
Afterwards, in the LF stove with 50kg Al ball and 270kg calcium carbide (CaC
2Content is more than 75%) add molten steel, heat then.Heat after 5 minutes, sampling analysis, the N content of molten steel is 0.0055%, C content is 0.10%; Continue heating 5 minutes then; After heating finished, (with the form feeding of carbonaceous cored-wire, this cored-wire was to process with the thick iron sheet parcel carbon dust of 0.6mm in molten steel, to feed carbon dust 150kg with feeding wire machine; The carbon dust C content is not less than 90%, and the C recovery is about 90%).Using apparatus for determination of oxygen to record molten steel actual oxygen content is 0.0008%.
Then, the molten steel after the processing of LF stove is transferred to the RH vacuum unit.The pure treatment time of vacuum unit is 11 minutes, and ultimate pressure is controlled to be 300Pa.Under ultimate pressure, handle and add FeTi30-A (the ferrotianium trade mark among the GB GB/T3282-2006) 41kg after 5 minutes (Ti content is 30%; All the other are Fe; The Ti recovery is 75%) (the raw material molten iron is for containing the Ti molten iron, so even do not add ferrotianium, residual all the time 0.003% the Ti of having an appointment in the molten steel).After vacuum-treat finishes, sampling analysis, the Ti content of molten steel, Als content and C content are respectively 0.010%, 0.012% and 0.19%, also are that Ti content and the Als content sum in the molten steel is 0.022%.
At last, on 6 machines 6 stream billet casters, molten steel casting become the strand of 200mm * 200mm.Tundish temperature is 1530 ℃ during continuous casting.The chemical composition of getting tundish steel sample analysis steel is 0.19% C, 0.25% Si, 0.73% Mn, 0.010% Ti, 0.012% Als, 0.013% Alt, 0.016% P, 0.008% S, 0.05% Cu, 0.04% Cr, 0.04% Ni and 0.03% Mo, and all the other are Fe and other unavoidable impurities.
200mm * 200mm continuously cast bloom forges into φ 30mm pole, and then is machined to the pole of φ 5 * 10mm and φ 15 * 60mm.Press total N content that GB/T 20124-2006 measures the pole of φ 5 * 10mm.The pole of φ 15 * 60mm dissolves → distillation through constant-current electrolysis → collection residue → (phosphoric acid+sulfuric acid) is sour, adopts the indophenol blue absorption spectrophotometry to measure chemical combination N content at last.Total N content is 0.0052%, and chemical combination N content is 0.0051%, and the Ti of this explanation 0.010% and 0.012% Als be the N in the steel fully fixedly.
Example 2:
In nominal capacity is the converter of 120 tons (actual tap is 120 tons～140 tons), add 140 tons of molten iron, utilize the function of Converter Oxigen Blowing decarburization that molten iron just is smelt molten steel.When molten steel just refines C content is 0.05%, and P content is 0.012%, and S content is 0.011%, and Si content is 0.02%, and Mn content is 0.03% o'clock, begins to tap to ladle.The amount of the molten steel after converter smelting is accomplished is 133 tons.
In tapping process; Add and can the molten steel oxygen level be removed to FeAl (aluminium content is 40%, and all the other the are Fe) 350kg below 0.0020% to ladle, and FeSi (Si content is 73%; All the other are Fe) 360kg and metal M n (Mn content is 98%, and all the other are Fe) 1200kg.After adding, using apparatus for determination of oxygen to record molten steel actual oxygen content is 0.0018%, and Si and Mn content are increased to 0.18% and 0.85% respectively in the molten steel.Then, with the Al line 30kg feeding molten steel of feeding wire machine with φ 10mm, the Als content of control molten steel is 0.02%.
Afterwards, in the LF stove with 50kg Al ball and 270kg calcium carbide (CaC
2Content is more than 75%) add molten steel, heat then.Heat after 5 minutes, sampling analysis, the N content of molten steel is 0.0060%, C content is 0.08%; Continue heating 5 minutes then, after heating finishes, in molten steel, feed carbon dust 245kg (with the form feeding of carbonaceous cored-wire, this cored-wire is to process with the thick iron sheet parcel carbon dust of 0.6mm, and the carbon dust C content is not less than 90%) with feeding wire machine.Using apparatus for determination of oxygen to record molten steel actual oxygen content is 0.0005%.
Then, the molten steel after the processing of LF stove is transferred to the RH vacuum unit.The pure treatment time of vacuum unit is 10 minutes, and ultimate pressure is controlled to be 300Pa.Under ultimate pressure, handle and add FeTi30-A (the ferrotianium trade mark among the GB GB/T3282-2006) 30kg after 5 minutes (Ti content is 30%; All the other are Fe; The Ti recovery is 75%) (the raw material molten iron is for containing the Ti molten iron, so even do not add ferrotianium, residual all the time 0.003% the Ti of having an appointment in the molten steel).After vacuum-treat finishes, sampling analysis, the Ti content of molten steel, Als content and C content are respectively 0.008%, 0.015% and 0.23%, also are that Ti content and the Als content sum in the molten steel is 0.023%.
At last, on 6 machines 6 stream billet casters, molten steel casting become the strand of 200mm * 200mm.Tundish temperature is 1545 ℃ during continuous casting.The chemical composition of getting tundish steel sample analysis steel is 0.22% C, 0.19% Si, 0.88% Mn, 0.0085% Ti, 0.015% Als, 0.015% Alt, 0.015% P, 0.009% S, 0.05% Cu, 0.05% Cr, 0.03% Ni and 0.03% Mo, and all the other are Fe and other unavoidable impurities.
200mm * 200mm continuously cast bloom forges into φ 30mm pole, and then is machined to the pole of φ 5 * 10mm and φ 15 * 60mm.Press total N content that GB/T 20124-2006 measures the pole of φ 5 * 10mm.The pole of φ 15 * 60mm dissolves → distillation through constant-current electrolysis → collection residue → (phosphoric acid+sulfuric acid) is sour, adopts the indophenol blue absorption spectrophotometry to measure chemical combination N content at last.Total N content is 0.0062%, and chemical combination N content is 0.0061%, and the Ti of this explanation 0.0085% and 0.015% Als be the N in the steel fully fixedly.
Example 3:
In nominal capacity is the converter of 120 tons (actual tap is 120 tons～140 tons), add 130 tons of molten iron, utilize the function of Converter Oxigen Blowing decarburization that molten iron just is smelt molten steel.When molten steel just refines C content is 0.10%, and P content is 0.015%, and S content is 0.008%, and Si content is 0.02%, and Mn content is 0.04% o'clock, begins to tap to ladle.The amount of the molten steel after converter smelting is accomplished is 123 tons.
In tapping process; Add and can the molten steel oxygen level be removed to FeAl (aluminium content is 40%, and all the other the are Fe) 350kg below 0.0020% to ladle, and FeSi (Si content is 73%; All the other are Fe) 700kg and metal M n (Mn content is 98%, and all the other are Fe) 1280kg.After adding, using apparatus for determination of oxygen to record molten steel actual oxygen content is 0.0018%, and Si and Mn content are increased to 0.35% and 0.98% respectively in the molten steel.Then, with the Al line 25kg feeding molten steel of feeding wire machine with φ 10mm, the Als content of control molten steel is 0.021%.
Afterwards, in the LF stove with 25kg Al ball and 250kg calcium carbide (CaC
2Content is more than 75%) add molten steel, heat then.Heat after 5 minutes, sampling analysis, the N content of molten steel is 0.0065%, C content is 0.15%; Continue heating 5 minutes then, after heating finishes, in molten steel, feed carbon dust 100kg (with the form feeding of carbonaceous cored-wire, this cored-wire is to process with the thick iron sheet parcel carbon dust of 0.6mm, and the carbon dust C content is not less than 90%) with feeding wire machine.Using apparatus for determination of oxygen to record molten steel actual oxygen content is 0.0005%.
Then, the molten steel after the processing of LF stove is transferred to the RH vacuum unit.The pure treatment time of vacuum unit is 12 minutes, and ultimate pressure is controlled to be 300Pa.Under ultimate pressure, handle and add FeTi30-A (the ferrotianium trade mark among the GB GB/T3282-2006) 38kg after 5 minutes (Ti content is 30%; All the other are Fe; The Ti recovery is 75%) (the raw material molten iron is for containing the Ti molten iron, so even do not add ferrotianium, residual all the time 0.003% the Ti of having an appointment in the molten steel).After vacuum-treat finishes, sampling analysis, the Ti content of molten steel, Als content and C content are respectively 0.010%, 0.008% and 0.21%, also are that Ti content and the Als content sum in the molten steel is 0.018%.
At last, on 6 machines 6 stream billet casters, molten steel casting become the strand of 200mm * 200mm.Tundish temperature is 1554 ℃ during continuous casting.The chemical composition of getting tundish steel sample analysis steel is 0.22% C, 0.37% Si, 0.97% Mn, 0.010% Ti, 0.008% Als, 0.009% Alt, 0.020% P, 0.005% S, 0.05% Cu, 0.05% Cr, 0.05% Ni and 0.03% Mo, and all the other are Fe and other unavoidable impurities.
200mm * 200mm continuously cast bloom forges into φ 30mm pole, and then is machined to the pole of φ 5 * 10mm and φ 15 * 60mm.Press total N content that GB/T 20124-2006 measures the pole of φ 5 * 10mm.The pole of φ 15 * 60mm dissolves → distillation through constant-current electrolysis → collection residue → (phosphoric acid+sulfuric acid) is sour, adopts the indophenol blue absorption spectrophotometry to measure chemical combination N content at last.Total N content is 0.0068%, and chemical combination N content is 0.0067%, and the Ti of this explanation 0.010% and 0.008% Als be the N in the steel fully fixedly.
Example 4:
In nominal capacity is the converter of 120 tons (actual tap is 120 tons～140 tons), add 130 tons of molten iron, utilize the function of Converter Oxigen Blowing decarburization that molten iron just is smelt molten steel.When molten steel just refines C content is 0.06%, and P content is 0.012%, and S content is 0.010%, and Si content is 0.02%, and Mn content is 0.05% o'clock, begins to tap to ladle.The amount of the molten steel after converter smelting is accomplished is 123 tons.
In tapping process; Add and can the molten steel oxygen level be removed to FeAl (aluminium content is 40%, and all the other the are Fe) 350kg below 0.0020% to ladle, and FeSi (Si content is 73%; All the other are Fe) 380kg and metal M n (Mn content is 98%, and all the other are Fe) 1100kg.After adding, using apparatus for determination of oxygen to record molten steel actual oxygen content is 0.0013%, and Si and Mn content are increased to 0.20% and 0.86% respectively in the molten steel.Then, with the Al line 38kg feeding molten steel of feeding wire machine with φ 10mm, the Als content of control molten steel is 0.028%.
Afterwards, in the LF stove with 25kg Al ball and 250kg calcium carbide (CaC
2Content is more than 75%) add molten steel, heat then.Heat after 5 minutes, sampling analysis, the N content of molten steel is 0.0065%, C content is 0.15%; Continue heating 5 minutes then, after heating finishes, in molten steel, feed carbon dust 100kg (with the form feeding of carbonaceous cored-wire, this cored-wire is to process with the thick iron sheet parcel carbon dust of 0.6mm, and the carbon dust C content is not less than 90%) with feeding wire machine.Using apparatus for determination of oxygen to record molten steel actual oxygen content is 0.0006%.
Then, the molten steel after the processing of LF stove is transferred to the RH vacuum unit.The pure treatment time of vacuum unit is 13 minutes, and ultimate pressure is controlled to be 300Pa.Under ultimate pressure, handle and add FeTi30-A (the ferrotianium trade mark among the GB GB/T3282-2006) 17kg after 5 minutes (Ti content is 30%; All the other are Fe; The Ti recovery is 75%) (the raw material molten iron is for containing the Ti molten iron, so even do not add ferrotianium, residual all the time 0.003% the Ti of having an appointment in the molten steel).After vacuum-treat finishes, sampling analysis, the Ti content of molten steel, Als content and C content are respectively 0.006%, 0.015% and 0.21%, also are that Ti content and the Als content sum in the molten steel is 0.021%.
At last, on 6 machines 6 stream billet casters, molten steel casting become the strand of 200mm * 200mm.Tundish temperature is 1540 ℃ during continuous casting.The chemical composition of getting tundish steel sample analysis steel is 0.21% C, 0.21% Si, 0.86% Mn, 0.006% Ti, 0.014% Als, 0.015% Alt, 0.015% P, 0.006% S, 0.05% Cu, 0.05% Cr, 0.03% Ni and 0.03% Mo, and all the other are Fe and other unavoidable impurities.
200mm * 200mm continuously cast bloom forges into φ 30mm pole, and then is machined to the pole of φ 5 * 10mm and φ 15 * 60mm.Press total N content that GB/T 20124-2006 measures the pole of φ 5 * 10mm.The pole of φ 15 * 60mm dissolves → distillation through constant-current electrolysis → collection residue → (phosphoric acid+sulfuric acid) is sour, adopts the indophenol blue absorption spectrophotometry to measure chemical combination N content at last.Total N content is 0.0065%, and chemical combination N content is 0.0063%, and the Ti of this explanation 0.006% and 0.014% Als be the N in the steel fully fixedly.
Claims (13)
1. the method for manufacture of a carbon steel may further comprise the steps:
(a) first steel-making water;
(b) be 0.05%～0.10% at the C of molten steel content, P content is not more than 0.015%, and S content is not more than at 0.020% o'clock, taps to ladle;
(c) in tapping process, the Si content of adjustment molten steel is 0.17%～0.37%, and Mn content is 0.70%～1.00%, and the oxygen level of adjustment molten steel is below 0.0020%;
(d) the Als content of control molten steel is 0.02%～0.03%, and Als representes the molten aluminium of acid;
(e) oxygen level of in ladle refining furnace, adjusting molten steel is below 0.0010%, and the C content of adjustment molten steel is 0.17%～0.23%;
(f) molten steel carried out the circulating vacuum degassing and handle, and the Ti content of adjustment molten steel is 0.006%～0.010%, thereby obtain carbon steel,
Said carbon steel comprises 0.17%～0.23% C, 0.17%～0.37% Si, 0.70%～1.00% Mn, 0.006%～0.010% Ti, 0.008%～0.015% Als; Surplus is Fe and unavoidable impurities, and the content of each element is weight percent content in the carbon steel.
2. method of manufacture according to claim 1; Wherein, unavoidable impurities comprises and is not more than 0.20% Cu, is not more than 0.25% Cr, is not more than 0.25% Ni, is not more than 0.15% Mo, is not more than 0.007% N, is not more than 0.025% P and is not more than 0.015% S in the said carbon steel.
3. method of manufacture according to claim 1 wherein, adopts converter to come steel-making water just in step (a).
4. method of manufacture according to claim 1, wherein, the oxygen level that in step (c), adopts at least a adjustment molten steel in aluminium ferromanganese, ferro-aluminum, ferrosilicon, manganese metal and the low carbon ferromanganese is below 0.0020%.
5. method of manufacture according to claim 1 wherein, adopts ferrosilicon to control the Si content of molten steel in step (c), adopts at least a Mn content of controlling molten steel in manganese metal, aluminium ferromanganese and the low carbon ferromanganese.
6. method of manufacture according to claim 1 wherein, adds the Als content that aluminium is controlled molten steel to molten steel in step (d).
7. method of manufacture according to claim 1 wherein, adopts CaC in step (e)
2Or CaC
2With the oxygen level of the combination of aluminium adjustment molten steel below 0.0010%.
8. method of manufacture according to claim 3, wherein, step (a) is included in the interior smelting molten iron of converter and obtains molten steel, in step (e), adopts CaC
2The adjustment molten steel oxygen level below 0.0010%, CaC
2Usage quantity be molten iron add-on * 95% * (1.8～2.2) * (0.7～1.0), said CaC
2The unit of usage quantity be kg, the unit of said molten iron add-on is a ton.
9. method of manufacture according to claim 1, wherein, in step (e) through adjust the C content of molten steel to molten steel feeding carbon.
10. method of manufacture according to claim 1; Wherein, Molten steel is carried out circulating vacuum degassing processed steps be included in and in the RH vacuum unit molten steel carried out the circulating vacuum degassing and handle, be not more than at pressure that the vacuum treated time is no less than 10 minutes under the condition of 300Pa.
11. method of manufacture according to claim 1, wherein, the step of Ti content of adjustment molten steel comprises ferro-titanium is added molten steel.
12. method of manufacture according to claim 1, wherein, said method of manufacture also is included in step (f) and afterwards molten steel is carried out continuous casting, and the temperature that continuous casting is operated the molten steel in the employed tundish is 1530 ℃～1555 ℃.
13. method of manufacture according to claim 1, wherein, the Ti content of said carbon steel and Als content sum are not less than 0.018%.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| EP1516934A1 (en) * | 2002-06-19 | 2005-03-23 | Nippon Steel Corporation | Oil well steel pipe excellent in crushing resistance characteristics after pipe expansion |
| CN1780929A (en) * | 2003-05-28 | 2006-05-31 | 住友金属工业株式会社 | Oil well steel pipe to be placed under ground and be expanded |
| CN101153367A (en) * | 2006-09-28 | 2008-04-02 | 上海梅山钢铁股份有限公司 | Fine crystal strengthen carbon constructional steel and manufacture process for hot-rolling thin slab thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| EP1516934A1 (en) * | 2002-06-19 | 2005-03-23 | Nippon Steel Corporation | Oil well steel pipe excellent in crushing resistance characteristics after pipe expansion |
| CN1780929A (en) * | 2003-05-28 | 2006-05-31 | 住友金属工业株式会社 | Oil well steel pipe to be placed under ground and be expanded |
| CN101153367A (en) * | 2006-09-28 | 2008-04-02 | 上海梅山钢铁股份有限公司 | Fine crystal strengthen carbon constructional steel and manufacture process for hot-rolling thin slab thereof |
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