CN103667733A - Method for smelting hollow billet steel ingot by using ingot stripping type electroslag furnace - Google Patents
Method for smelting hollow billet steel ingot by using ingot stripping type electroslag furnace Download PDFInfo
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- CN103667733A CN103667733A CN201310699087.1A CN201310699087A CN103667733A CN 103667733 A CN103667733 A CN 103667733A CN 201310699087 A CN201310699087 A CN 201310699087A CN 103667733 A CN103667733 A CN 103667733A
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Abstract
The invention discloses a method for smelting a hollow billet steel ingot by using an ingot stripping type electroslag furnace. An outer crystallizer, an inner crystallizer and a bottom water tank are arranged in the ingot stripping type electroslag furnace, and an annular electrode bar is arranged between the outer crystallizer and the inner crystallizer; liquid slag charge is added into the ingot stripping type electroslag furnace, and arc striking is performed for smelting; the normal smelting current is controlled to be 21,000-25,000 A, the normal smelting voltage is controlled to be 78-88 V, and the smelting speed of the annular electrode bar is controlled to be 14-22 kg/min; and when a smelt liquid steel level formed by smelting is located in the position of 1/2-2/3 of the height of a section used for solidifying liquid steel in the inner crystallizer, the bottom water tank is controlled to drive a steel ingot to move downwards for ingot stripping, the ingot stripping speed is controlled to be 3-16 mm/min, the downward friction force suffered by the inner crystallizer is controlled to be smaller than 40% of the minimum deformation force which can be borne by the inner crystallizer, and the hollow billet steel ingot is obtained after the steel ingot is completely stripped. The method can smelt the qualified hollow billet steel ingot, and the quality and the production efficiency of a pipe fitting are improved greatly.
Description
Technical field
The present invention relates to technical field of ferrous metallurgy, more particularly, relate to a kind of method that stripping formula electroslag furnace is smelted hollow bloom steel ingot.
Background technology
China electroslag furnace is smelted and mainly be take traditional electrical slag hearth (generally consisting of support arm, column, short net, transformer, holder ingot chassis etc.) and electroslag furnace under protective Ar gas stove as main; and conventionally adopt electroslag furnace to smelt hollow bloom steel ingot and need to carry out complicated perforation link; be difficult to guarantee the inside and outside concentricity in hole and the homogeneity of wall thickness, all unfavorable for quality and the production efficiency of pipe fitting.
At present, stripping formula electroslag furnace is just progressively development abroad, adopts stripping formula electroslag furnace to smelt hollow bloom steel ingot and substantially belongs to vacancy at home and abroad.
The present invention aims to provide the method that stripping formula electroslag furnace that a kind of steady quality, efficiency are high is smelted hollow bloom steel ingot.
Summary of the invention
For existing deficiency in prior art, the object of the invention is to solve one or more problem
The object of the present invention is to provide a kind of method that can smelt up-to-standard hollow bloom steel ingot.
To achieve these goals, the invention provides a kind of stripping formula electroslag furnace and smelt the method for hollow bloom steel ingot, in described stripping formula electroslag furnace, outer crystallizer, interior crystallizer and end water tank are set, said method comprising the steps of: ring electrode rod is placed between described outer crystallizer and interior crystallizer, in stripping formula electroslag furnace, add liquid slag charge, the starting the arc is smelted, wherein, controlling normal smelting electric current is 21000～25000A, controlling normal smelting voltage is 78～88V, and the burn-off rate of controlling annular electrode bar is 14～22Kg/min; When the molten steel face smelt forming is arranged in interior crystallizer when solidifying 1/2～2/3 place of section height of molten steel, control end water tank drive steel ingot moves down and carries out stripping, controlling stripping speed is 3～16mm/min, and to control the suffered downward frictional force of interior crystallizer be below 40% of minimal deformation power that interior crystallizer can bear, after steel ingot is extracted out completely, come out of the stove and obtain hollow bloom steel ingot.
According to stripping formula electroslag furnace of the present invention, smelt an embodiment of the method for hollow bloom steel ingot, described ring electrode rod adopts many electrode bars to be welded.
According to stripping formula electroslag furnace of the present invention, smelt an embodiment of the method for hollow bloom steel ingot, described method is also included in the step that described ring electrode rod exhausts the ring electrode rod more renewing immediately afterwards.
According to stripping formula electroslag furnace of the present invention, smelt an embodiment of the method for hollow bloom steel ingot, in changing the process of ring electrode rod, adopt outer crystallizer to the liquid slag charge power supply of steel ingot top.
According to stripping formula electroslag furnace of the present invention, smelt an embodiment of the method for hollow bloom steel ingot, described liquid slag charge is to adopt CaF
2: Al
2o
3: CaO:SiO
2: after five yuan of slag system fusings that the quality of MgO is 30-50:20-35:20-35:3-10:1-5 than scope, obtain.
According to stripping formula electroslag furnace of the present invention, smelt an embodiment of the method for hollow bloom steel ingot, described method also comprises the step and the step of carrying out Slow cooling of steel ingot being carried out to feeding filling.
The present invention adopts stripping formula electroslag furnace and smelts up-to-standard hollow bloom steel ingot by adjusting the reasonable control of slag system and parameters, reduced complicated perforation link, guarantee the concentricity in inside and outside hole and the homogeneity of wall thickness, greatly improved quality and the production efficiency of pipe fitting.
Accompanying drawing explanation
Fig. 1 is the sampling point schematic diagram of the hollow bloom steel ingot smelted in example of the present invention.
Embodiment
The method of stripping formula electroslag furnace of the present invention being smelted to hollow bloom steel ingot below in conjunction with embodiment is described in detail.
General stripping formula electroslag furnace is provided with outer crystallizer and end water tank, and extract the steel ingot of smelting out and make outer crystallizer keep motionless by moving down of end water tank, the molten steel pressure of crystallizer outside cooling under, ecto-entad gradually solidification and crystallization forms steel ingot, but it cannot be for the production of hollow bloom steel ingot.
Stripping formula electroslag furnace of the present invention is except possessing the structure and characteristics of general stripping formula electroslag furnace, also be provided with interior crystallizer, this interior crystallizer can make to be formed centrally in molten steel and interior crystallizer equal and opposite in direction or bigger hole, form thus the steel ingot of ring-type, and making steel ingot from inwall to outer wall and cooling gradually to outer wall from inwall, the steel ingot solidifying moves down and is drawn out of and forms hollow bloom steel ingot with end water tank.But in smelting the process of hollow bloom steel ingot, due to the certain enclasping force of the cooling contraction of steel ingot meeting to interior crystallizer generation, and the pulling force that end water tank moves down can cause steel ingot and interior crystallizer to produce certain frictional force.When frictional force is excessive, interior crystallizer can move down with steel ingot, causes deformed damaged and smelts and end.The longer inside contraction of identical steel grade setting time is larger, the frictional force producing with interior crystallizer is larger, steel ingot and interior crystallizer contact area are larger, the frictional force of the more rough generation of contact surface is also larger, and therefore controlling smelting parameter and stripping parameter is the key of smelting qualified hollow bloom steel ingot.
The exemplary embodiment of smelting the method for hollow bloom steel ingot according to stripping formula electroslag furnace of the present invention, arranges outer crystallizer, interior crystallizer and end water tank in this stripping formula electroslag furnace.Wherein, outer crystallizer is used for making steel ingot cooling from outside to inside, interior crystallizer is used for making steel ingot from inside to outside cooling, end water tank is for providing water coolant to interior crystallizer and outer crystallizer, and end water tank also uses as the stripping drive unit that solidifies rear steel ingot, and the steel ingot solidifying is drawn out of along with moving down of end water tank.When producing, can adopt the interior crystallizer of different size and outer crystallizer to combine, meet the Production requirement of the hollow bloom steel ingot of smelting different size.
Particularly, said method comprising the steps of:
First, carry out raw material preparation.According to the composition of the hollow bloom steel ingot of required smelting, prepare electrode bar, then many electrode bars are welded to one another and form ring electrode rod.
Then, ring electrode rod is placed between outer crystallizer and interior crystallizer, in stripping formula electroslag furnace, adds liquid slag charge, the starting the arc is smelted.For internal surface that steel ingot is contacted with interior crystallizer is smooth, the frictional force when reducing stripping continuously, need to select the slag charge of good toughness, good fluidity.According to one embodiment of present invention, adopt CaF
2: Al
2o
3: CaO:SiO
2: after five yuan of slag system fusings that the quality of MgO is 30-50:20-35:20-35:3-10:1-5 than scope, obtain above-mentioned liquid slag charge, wherein SiO
2slag crust toughness can be provided and can form uniform and stable slag crust, if SiO
2content too much easily causes inclusion higher.And, adopt the striking of liquid slag charge, first solid slag is molten into liquid slag charge in independently changing slag hearth, then pours in crystallizer and carry out striking smelting, adopt melt cinder striking at the smelting initial stage, more easily to control the stability of smelting electric current and voltage.
When smelting, controlling normal smelting electric current is 21000～25000A, and controlling normal smelting voltage is 78～88V, and the burn-off rate of control electrode rod is 14～22Kg/min, comparatively suitable to control the setting time of steel ingot in crystallizer.In the normal smelting stage, if burn-off rate lower than 14Kg/min, setting time is longer, easily causes frictional force larger, interior crystallizer is prone to deformed damaged; If burn-off rate is higher than 22Kg/min, setting time is shorter, although can reduce friction and prevent the deformed damaged of interior crystallizer, but there is the situations such as bleed-out, leakage slag in the too short halfway position of ingot solidification of can causing again of setting time, therefore need to control suitable setting time by controlling smelting parameter.
When the molten steel face smelt forming is positioned at interior crystallizer when solidifying 1/2～2/3 place of section height of molten steel, control end water tank and drive steel ingot to move down to carry out stripping, and 1/2～2/3 place of above-mentioned height judges according to height from the bottom to top.Wherein, by stripping speed control at 3～16mm/min, the inside and outside crystallizer combination of different size can be produced the hollow ingot of plurality of specifications, but the optimum stripping speed of its correspondence is also different, should carry out according to concrete combination mould specification the working control of stripping speed.For example, the formed annular cross section of the crystallizer of combination is long-pending less, and stripping speed should faster (as: the stripping speed that the crystallizer of Φ 450/650mm combines should be controlled at 10～16mm/min); And the formed annular cross section of crystallizer of combination is long-pending larger, stripping speed should slower (as: the stripping speed that the crystallizer of Φ 200/900mm combines should be controlled at 3～5mm/min).Take molten steel face interior crystallizer for solidify section height from the bottom to top 1/2～2/3 between be judging criterion, control stripping speed steel liquid level regulated.If steel liquid level is during higher than 2/3 height, steel ingot and interior crystallizer are long duration of contact, and solidification shrinkage is large, easily causes the stressed excessive deformation of interior crystallizer to damage; If steel liquid level is during lower than 1/2 height, setting time is too short can cause again the halfway position of ingot solidification to occur bleed-out, leak slag.
When stripping, control below 40% of minimal deformation power that the suffered downward frictional force of interior crystallizer is interior crystallizer, after steel ingot is extracted out completely, come out of the stove and obtain hollow bloom steel ingot.By detecting the height of steel ingot on interior crystallizer, can judge the contact area of steel ingot and interior crystallizer, and the frictional force of the larger generation of contact area of steel ingot and interior crystallizer is also larger, by controlling stripping speed and regulating the height of steel ingot on interior crystallizer can control the change direction of frictional force and the setting time of steel ingot.By frictional force proofing unit is set in stove, detect in real time the size of the suffered downward frictional force of crystallizer simultaneously, and control minimal deformation power that the suffered downward frictional force of interior crystallizer is interior crystallizer below 40% to avoid interior crystallizer distortion.In addition, can also judge whether in time to occur bleed-out according to the leaving water temperature(LWT) of crystallizer etc., leak the abnormal conditions such as slag.
In order to obtain longer hollow bloom steel ingot, the ring electrode rod preferably more renewing immediately after ring electrode rod exhausts, at one group of ring electrode rod, has smelted horse back and changed another and organize ready ring electrode rod and proceed smelting, carried out repeatedly such exchange Electrode and can obtain longer hollow bloom steel ingot.But, because ring electrode rod in Renewal process has left liquid slag charge, the temperature of liquid slag charge can decline rapidly, in order to prevent that temperature from declining, cause steel ingot and local slag to solidify the quality problems that cause simultaneously, outside preferably adopting in Renewal process, crystallizer is to the liquid slag charge power supply above steel ingot, so that the temperature of liquid slag charge declines slowly and prevents steel ingot rapid solidification, avoid frictional force to increase the quality problems that cause.After having changed ring electrode rod, can withdraw from the outer crystallizer electric installation for powering.In the process of whole replacing, end water tank still continues to move down, but the downward frictional force that need be subject to according to interior crystallizer is adjusted stripping speed, particularly, the increase of the downward frictional force that stripping speed need be subject to interior crystallizer increases and the reducing and reduce of the downward frictional force that is subject to interior crystallizer, and then the increase along with the burn-off rate of the rising of liquid slag material temperature degree and new ring electrode rod progresses into normal smelting.
In addition, in order to guarantee the quality of hollow bloom steel ingot, need to carry out feeding filling to steel ingot, and steel ingot is carried out coming out of the stove after Slow cooling.Generally finishing to smelt beginning feeding filling in first 2～10 minutes, feeding is fills up to smelt and finishes, and the time of feeding and cooling time can specifically be selected according to the specification of pipe and composition.
Below in conjunction with concrete example, describe the present invention in detail.
example:
Equipment: stripping formula electroslag furnace;
Raw material is prepared: adopting Φ 160 ± 2mm, the length of rolling is the electrode bar of 3000 ± 200mm, sinuousness≤5mm/m, and every 10 electrode bars are connected into one group of ring electrode rod according to annular welds, prepares two groups of ring electrode rods and smelts hollow bloom steel ingot;
The steel grade of smelting: P91;
Inside and outside crystallizer specification is respectively Φ 500mm, Φ 900mm;
Slag system and mass ratio thereof: CaF
2: Al
2o
3: CgO:SiO
2: MgO=40:30:20:5:5;
The quantity of slag: 360kg;
Preparation work: carry out the insulation between interior crystallizer, outer crystallizer, end water tank, prevent that local conduction from puncturing copper coin and causing leaking; Between interior crystallizer, outer crystallizer and end water tank, use insulating material shutoff tight, prevent smelting initial stage leakage slag.
Smelt: in independently changing slag hearth, above-mentioned solid slag is molten into liquid slag charge, more liquid slag charge is poured in electroslag furnace ring electrode rod is carried out to starting the arc smelting.The burn-off rate of controlling melting electric current and be 23000 ± 2000A, melting voltage and be 83 ± 5V, ring electrode rod is 17～20Kg/min.When molten steel face is positioned at interior crystallizer when solidifying 1/2 place of section height of molten steel, drive end water tank to move down and carry out stripping, stripping speed is increased at 5.5 ± 0.5mm/min gradually by 0mm/min, and stable be controlled at 5.5 ± 0.5mm/min, finally make downward frictional force that interior crystallizer is subject to be controlled at interior crystallizer minimal deformation power 40% with interior to prevent interior crystallizer deformed damaged.During this time ring electrode rod is changed, and powered the temperature of liquid slag charge is declined slowly to the liquid slag charge of steel ingot top by outer crystallizer, avoid exchange process because the temperature of liquid slag charge reduces rapidly the ingot quality problem causing.More finish changing after electrode bar, withdraw from the outer crystallizer electric installation for powering.In exchange process, end water tank still continues to move down, and the downward frictional force size being subject to according to interior crystallizer is adjusted stripping speed in real time, progresses into afterwards the normal smelting stage.Wherein, make steel ingot feeding 1min above minimum to reduce the volumetric shrinkage of process of cooling generation and to realize the contraction degree of depth, stop afterwards smelting rear continuation stripping to steel ingot and leave crystallizer, and steel ingot more than Slow cooling 30min, is come out of the stove after having solidified in stove.
Steel ingot assay: the internal diameter of prepared hollow bloom steel ingot is that Φ 500mm, external diameter are Φ 900mm, its forging casting skin specification (being non-mach trimmed size) is Φ 840 * 140mm.Fig. 1 shows the location map that smelted hollow bloom steel ingot is sampled, and altogether each 12 positions, two of steel billet is sampled, and the composition of gained is as shown in table 1.
The sampling composition assay of the hollow bloom steel ingot in table 1 example
Afterwards, the hollow bloom steel ingot after forging is carried out to sampling analysis to understand the internal soundness of hollow bloom steel ingot, its analytical results is as shown in table 2
Table 2 sampling analysis result
As can be known from the above table, adopt starting the arc end, feeding end and outer wall, the mid-depth of P91 steel hollow bloom steel ingot prepared by method of the present invention, the principal element at each position of inwall, the distribution of residual element is more even, inclusion content is few, steady quality and size conforms standard.
In sum, stripping formula electroslag furnace of the present invention is smelted the method for hollow bloom steel ingot and is utilized stripping formula electroslag furnace to smelt and smelt up-to-standard hollow bloom steel ingot by adjusting the reasonable control of slag system and parameters, reduced complicated perforation link, guarantee the concentricity in inside and outside hole and the homogeneity of wall thickness, greatly improved quality and the production efficiency of pipe fitting.
The invention is not restricted to above-described embodiment, in the situation that not departing from the claims in the present invention protection domain, can carry out various changes and modifications.
Claims (6)
1. stripping formula electroslag furnace is smelted a method for hollow bloom steel ingot, it is characterized in that, in described stripping formula electroslag furnace, outer crystallizer, interior crystallizer and end water tank is set, and said method comprising the steps of:
Ring electrode rod is placed between described outer crystallizer and interior crystallizer, in stripping formula electroslag furnace, add liquid slag charge, the starting the arc is smelted, wherein, controlling normal smelting electric current is 21000～25000A, controlling normal smelting voltage is 78～88V, and the burn-off rate of controlling annular electrode bar is 14～22Kg/min;
When the molten steel face smelt forming is arranged in interior crystallizer when solidifying 1/2～2/3 place of section height of molten steel, control end water tank drive steel ingot moves down and carries out stripping, controlling stripping speed is 3～16mm/min, and to control the suffered downward frictional force of interior crystallizer be below 40% of minimal deformation power that interior crystallizer can bear, after steel ingot is extracted out completely, come out of the stove and obtain hollow bloom steel ingot.
2. stripping formula electroslag furnace according to claim 1 is smelted the method for hollow bloom steel ingot, it is characterized in that, described ring electrode rod adopts many electrode bars to be welded.
3. stripping formula electroslag furnace according to claim 1 is smelted the method for hollow bloom steel ingot, it is characterized in that, described method is also included in the step that described ring electrode rod exhausts the ring electrode rod more renewing immediately afterwards.
4. stripping formula electroslag furnace according to claim 3 is smelted the method for hollow bloom steel ingot, it is characterized in that, in changing the process of ring electrode rod, adopts outer crystallizer to the liquid slag charge power supply of steel ingot top.
5. stripping formula electroslag furnace according to claim 1 is smelted the method for hollow bloom steel ingot, it is characterized in that, described liquid slag charge is to adopt CaF
2: Al
2o
3: CaO:SiO
2: after five yuan of slag system fusings that the quality of MgO is 30-50:20-35:20-35:3-10:1-5 than scope, obtain.
6. stripping formula electroslag furnace according to claim 1 is smelted the method for hollow bloom steel ingot, it is characterized in that, described method also comprises the step and the step of carrying out Slow cooling of steel ingot being carried out to feeding filling.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104164573A (en) * | 2014-07-11 | 2014-11-26 | 武汉钢铁(集团)公司 | Premelting slag used for producing container steel of hydrogenation reactor and application thereof |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1160614A (en) * | 1996-03-26 | 1997-10-01 | 杨兆顺 | Seamless stainless-steel pipe smelting and rolling technology |
| CN103334015A (en) * | 2013-06-18 | 2013-10-02 | 东北大学 | Low-pollution energy conservation slag system used for manufacturing hollow ingot by remelting electroslag in ingot drawing way |
-
2013
- 2013-12-18 CN CN201310699087.1A patent/CN103667733B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1160614A (en) * | 1996-03-26 | 1997-10-01 | 杨兆顺 | Seamless stainless-steel pipe smelting and rolling technology |
| CN103334015A (en) * | 2013-06-18 | 2013-10-02 | 东北大学 | Low-pollution energy conservation slag system used for manufacturing hollow ingot by remelting electroslag in ingot drawing way |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104164573A (en) * | 2014-07-11 | 2014-11-26 | 武汉钢铁(集团)公司 | Premelting slag used for producing container steel of hydrogenation reactor and application thereof |
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