CN104745962A - Smelting method of 21-10Mn7Mo steel ingot - Google Patents

Abstract

The invention provides a smelting method of a 21-10Mn7Mo steel ingot, belonging to the technology of solid cored welding wires for gas-shielded arc welding, and in particular provides a smelting method and a steel ingot prepared by using the method. The smelting method comprises the following steps: I smelting an electroslag remelting electrode by using an arc furnace back blowing method; II refining by electroslag remelting. The steel ingot comprises the following chemical components by mass percent: not more than 0.10% of C, not more than 0.8% of Si, 5.5-8.0% of Mn, not more than 0.030% of P, not more than 0.020% of S, 9.0-11.0% of Ni, 19.0-22.0% of Cr and 0.5-2.0% of Mo, wherein the Mn/Mo ratio is controlled to be 7-7.5. The cast ingot with high purity, low sulfur content, less non-metallic inclusions, uniform chemical components and uniform and dense steel ingot tissues can be obtained by adopting the smelting method. The smelting method can provide quality guarantee for late welding wire processing.

Description

The smelting process of 21-10Mn7Mo steel ingot

Technical field

This case belongs to welding technology field, relates to the preparation method of the solid wire of gasshielded arc welding and final product thereof and processing unit thereof.The method of particularly smelting and steel ingot thereof.

Background technology

The application in automatic technology of stainless steel welding stick, welding rod gets more and more, but the common quality problems of the stainless steel welding stick prepared of prior art are that welding wire outward appearance is bad, wire feed is stable not, are therefore difficult to the requirement meeting high automation welding set.

Generally known, Quality of Final Welding Wire has relation closely with the slight change of the chemical composition that steel-making causes, have relation closely with the foreign matter content of material composition, importantly the processing method prepared of welding wire and processing unit are related to the work in-process of welding wire, the quality of final product.Industry did a lot of effort in this respect for this reason, and prior art includes but not limited to:

As Chinese patent 200510109991.8 discloses a kind of solid wire for gas shielded arc welding, it consists of, containing Si:0.70 to 1.00 quality %, Mn:1.50 to 1.90 quality %, S:0.005 to 0.025 quality %, Ti:0.19 to 0.25 quality %, Mo:0.12 to 0.35 quality %, C:0.020 to 0.100 quality %, below B:0.0050 quality % and Cu:0.45 quality %, restriction below P:0.020 quality %, below 0:0.0160 quality %, Si/Mn is more than 0.385, the total content of Mn and Mo is below 2.20 quality %, the total content of S and O is below 0.034 quality %, in addition, C content (quality %) is [C], when B content (quality %) is [B], the relation of [C] and [B] meets given condition.This welding wire, to the intensity carbon steel that is below 520N/mm2 level carry out carbonic acid gas shielded arc welding connect time, high-level efficiency and the mechanical property of weld part is excellent.

For another example Chinese patent 200310100196.3 discloses a kind of high-tensile electrode, and this invention belongs to field of welding material.This welding rod is a kind of welding rod in as-welded lower use with high strength, can be used for the High Strength Structural Steel that welding buckling strength is greater than 950MPa level.The feature of this invention high-tensile electrode is that the deposited metal composition forming welding rod is: C≤0.07%; Si0.1-0.6%; Mn1.2-1.9%; Ni2.6-3.8%; Cr0.41-1.50%; Mo0.66-1.6%; Ti0.003-0.03%; All the other are Fe.The deposited metal of this welding rod has good comprehensive mechanical property, and its tensile strength is greater than 1000MPa; Yield strength is at more than 950MPa; 27J is greater than at the ballistic work of-50 DEG C.

And for example Chinese patent 200710103490.8 discloses a kind of solid wire, be 0.005 ~ 0.060 quality % containing C, Si is 0.60 ~ 1.00 quality %, Mn is 1.10 ~ 1.65 quality %, S is 0.045 ~ 0.090 quality %, O is 0.0015 ~ 0.0100 quality %, and the content of described C and described S add up to below 0.125 quality %, containing P at below 0.017 quality %, surplus is Fe and inevitable impurity, in described impurity, Ti is limited in below 0.15 quality %, B is limited in below 0.0050 quality %, N is limited in below 0.0075 quality %, in addition Cr, Ni, Al, Nb, V, Zr, La and Ce is limited in below 0.20 quality % respectively.

Also has prior art H1Cr21Ni10Mn6 welding wire, be mainly used in the automatic welding such as heavy type, oversize vehicle, this case is also the further improvement as Developed Background, object is the tensile strength improving welding wire further, improve the tensile strength of its deposited metal, include but not limited to following open for this reason in addition:

As Chinese patent 201110104281.1 discloses a kind of welding wire, wire rod and application thereof, it relates to wire rod and welding wire, and its chemical composition is by weight percentage: C≤0.05%, Si:0.10-0.60%, Mn:0.3-1.2%, S≤0.015%, P≤0.020%, Cr:1.0-2.0%, Ni:3.0-5.0%, Cu:0.05-0.40%, Ti:0.03-0.20%, O≤0.010%, N≤0.010%, H≤0.0005%, surplus is Fe and inevitable impurity element.The application of welding wire in the interalloy high durable structure iron for more than tensile strength 550MPa welds.

It is urgently to be resolved hurrily to there is following problems in existing technology.

Smelting problem, composition of raw material and homogeneity are the preorder key links of relation Quality of Final Welding Wire, therefore provide by smelting procedure the steel ingot that homogeneity is better, purity is higher, being the fundamental technology link preparing high quality welding wire, is also that industry pursues the important process link constantly made new advances.

This case welding wire is the innovation on the basis of existing H1Cr21Ni10Mn6 welding wire, comprise and add appropriate Mo, the corresponding content improving Mn simultaneously, problem is that the change of material composition thus can bring difficulty in process to the production in later stage, generally known, the content of molybdenum in steel alloy is when certain limit, and molybdenum can make the plasticity of steel alloy and toughness decline, and therefore industry urgently solves such problem by the improvement comprising the processing method of smelting.

Summary of the invention

Problem to be solved by this invention is the above-mentioned defect overcoming aforementioned techniques existence, and the steel ingot a kind of smelting process for 21-10Mn7Mo welding wire being provided and preparing by the method.

Technical solution problem of the present invention is taked following technical scheme to realize, according to the smelting process of a kind of 21-10Mn7Mo steel ingot provided by the invention, comprise first step electric arc furnace Returning blowing keto technique to smelt esr electrode and second step esr and carry out refining, wherein, described steel ingot chemical composition quality % comprises: carbon C≤0.10, silicon Si≤0.8, manganese Mn5.5-8.0, phosphorus P≤0.030, sulphur S≤0.020, nickel 9.0-11.0, chromium Cr19.0-22.0, molybdenum Mo0.5-2.0; Or/and Mn/Mo ratio controls at 7-7.5;

This case technical solution problem can also take following technical scheme to realize further:

The smelting process of aforementioned steel ingot, wherein, described steel ingot chemical composition quality % is by carbon C≤0.10, silicon Si≤0.8, manganese Mn5.5-8.0, phosphorus P≤0.030, sulphur S≤0.020, nickel 9.0-11.0, chromium Cr19.0-22.0, molybdenum Mo0.5-2.0, and surplus is iron Fe and inevitable impurity composition; Or/and Mn/Mo ratio controls at 7-7.5.

The smelting process of aforementioned steel ingot, wherein, raw materials for metallurgy adopts the interpolation of Mn element to adopt Fe content to be the electrolytic manganese of 97.25%, and the interpolation of Cr element adopts purity to be the extra low carbon ferrochromium of 99.22%; Adding of Ni element adopts purity to be the electrolytic nickel of 99.98%, molybdenum element also adopt purity be 99.96% metal molybdenum, the interpolation of element silicon adopts purity to be the industrial silicon of 99.6%.

The smelting process of aforementioned steel ingot, wherein, the technological process of described first step successively: fettling, charging, melting period, oxidation period, reduction period, tapping, casting resmelting electrode;

The smelting process of aforementioned steel ingot, wherein, the selection of slag system in the technological process of described second step: the slag ANF-8 selecting first slag system CaF2-Al2O3-CaO slag system, proportioning is CaF2:Al2O3:CaO=60%:20%:20%.

The smelting process of aforementioned steel ingot, wherein, in described second step, select the fusing point of slag system should the fusing point of proportion molten steel low 100 ~ 200 DEG C; Or/and described slag melting point is equivalent to 1250 DEG C; The selection of slag system: the slag ANF-8 selecting first slag system CaF2-Al2O3-CaO slag system, proportioning is CaF2:Al2O3:CaO=60%:20%:20%.

The smelting process of aforementioned steel ingot, wherein, in described second step, controlled melting speed and ingot diameter ratio are no more than 1; The measure of control cooled in described second step: there is between steel ingot and crystallizer the clearance configurations for the formation of slag crust; It is 1 ~ 2mm that the gap of described slag crust can meet the slag crust thickness formed, and thickness of the slag crust uniformity.

The smelting process of aforementioned steel ingot, wherein, in described second step thickness of the slag crust uniformity technological measure in: cooling intensity controls as cooling is gentle, and cooling should not change suddenly; Stating crystallizer leaving water temperature(LWT) in second step controls at 40-50 DEG C or 50-60 DEG C, and inflow temperature should lower than 30 DEG C; Or/and quote circulation soft water, water rate control is at 30 ~ 45m ³/ t.

The smelting process of aforementioned steel ingot, wherein, in fettling step: fettling material application bittern stirs, not handy clear water stirs; Or/and, in charging procedure: Ni, Mo are placed on the region of relatively-high temperature in stove, arcing district can not be placed on; The control of electrode of described melting period is: electrode wears the band impedance of well stage, adopts high-power power transmission; Or/and, add lime material, fluorite material, for stable arc in batches; Or/and, melting period oxygen blown control: start oxygen blast when furnace temperature reaches more than 950 DEG C, oxygen pressure-controlled is being not more than 0.4MPa; Or/and, melting period dephosphorization control: in the load melting later stage, when molten steel carbon content meets preset value, carry out low temperature dephosphorization, add lime or broken ore in good time, fire door flows slag dephosphorization automatically.

The smelting process of aforementioned steel ingot, wherein, described in add the opportunity of ore and the control of amount: add ore in batches, often criticize ore deposit amount and be set to 3-4kg or 4-5kg, interval 3-4 minute or 4-5 minute between adjacent batch.Described oxidation period is dephosphorization, decarburization; Degasification: comprise denitrogenate, dehydrogenation; Remove inclusion in molten steel; Its oxidation period dephosphorization, decarburization order be first dephosphorization, rear decarburization; Temperature Control sequence is: first low temperature, rear high temperature; Slag making order is: first volume, on a small quantity rear; Feed order is, first adds ore, rear oxygen blast.Oxidation period slag control: by adding ore, lime in time, control slag flowing; Or/and the quantity of slag of slag controls be equivalent to 2% ~ 3% of molten steel amount; Or/and slag basicity controls be equivalent to 2.5 ~ 3.

The smelting process of aforementioned steel ingot, wherein, sinter thickness controls be equivalent to 40mm ~ 60mm.In reduction period, lime, adding of fluorite add rapidly after removing oxidation sludge, and ratio is 3:1; Produce thin slag, after thin slag is formed, then add lime in batches, adjustment slag, and add electrolytic manganese; Or/and employing Ca-Si powder, Al powder carry out diffusive deoxidation, after slag is white, fully stirs, get Duplicate Samples and carry out total analysis; Or/and insulation reduction step selects small power to heat up, and can select high-power intensification before tapping.Wherein, in the control of tapping step: after adding alloy, the time between tapping should be relatively long, controls be greater than 5 minutes; Or/and Al0.4 ~ 0.5 ㎏/t is inserted in tapping; Or/and tapping temperature selects 1580 ~ 1590 DEG C or 1590 DEG C-1600 DEG C.

The smelting process of aforementioned steel ingot, wherein, described first step, wherein, molten steel temperature reaches 1400-1600 DEG C, at high temperature realizes high chromium steel liquid decarbonization and protecting chromium;

The smelting process of aforementioned steel ingot, wherein, the control of cast resmelting electrode: cast controls after tapping opportunity, leave standstill 3 ~ 7 minutes, whether measuring tempeature meets pouring temperature condition; Or/and controlling pouring temperature is 1450 ~ 1460 DEG C or 1460 DEG C ~ 1470 DEG C or 1470 DEG C-1480 DEG C.

The smelting process of aforementioned steel ingot, wherein, casting rate is 110 ~ 120kg/s; Or 120 ~ 130kg/s or 130 ~ 140kg/s, or 140 ~ 150kg/s; Or/and opening stream can more greatly, and when molten steel rises to ingot body more than 1/3, or full stream is noted soon; Wherein, Mn/Mo is than controlling as 7-7.1, or 7.2-7.3, or 7.4-7.5.

Or/and in described second step, steel ingot is set to elongated ingot shape, the ratio of steel ingot diameter Di and steel ingot length is 1:5 or 1:5.3; Crystallizer diameter D _knotmeet with the relation of Di steel ingot diameter: D _knot=1.03*Di; Crystallizer height H and crystallizer diameter D _knotrelation meet: H ≈ (1.5 ~ 2.0) * D _knot; Electrode diameter d _polemeet with the relation of electrode length: stacking factor meets d _pole/ D _knot; Arranging smelting electric current is 8000 peaces.

The present invention compared with prior art has significant advantage and beneficial effect, and from above technical scheme, the present invention is under the structural allocation of excellence, and remarkable advantage particular embodiment in an embodiment, also has:

The steel ingot that this case is prepared by the smelting technology method provided, prepares high-quality welding wire for postorder and lays a good foundation.This case adopts arc smelting just after ingot, then purifies by the method for esr, thus can obtain that purity is high, sulfur-bearing is low, non-metallic inclusion is few, chemical composition is even and the ingot casting of ingot structure's even compact.The smelting technology that this case provides obtain 21-Mn7Mo cast metals there is good structure property, for the welding wire processing in later stage provides quality assurance.This case completes aforesaid technical purpose.

The specific embodiment of the present invention is provided in detail by following examples and accompanying drawing thereof.

Accompanying drawing explanation

Fig. 1 is the macrograph of electric arc furnace smelting sample.

Fig. 2 is the distribution photo of Mn element in the tissue of electric arc furnace smelting sample.

Fig. 3 is the macrograph of electric arc furnace+esr sample.

Fig. 4 is the distribution photo of Mn element in the tissue of electric arc furnace+esr sample.

Fig. 5 is the distribution photo of Mo element in the tissue of electric arc furnace+esr sample.

Embodiment

Below in conjunction with preferred embodiment, to according to embodiment provided by the invention, feature and effect thereof, be described in detail as follows; In order to simple and clearly object, the hereafter appropriate description eliminating known technology, in order to avoid the description of those unnecessary details impact to the technical program.

Shown in Fig. 1-5, a kind of smelting process of 21-10Mn7Mo welding wire and the steel ingot prepared by the method.The material composition unit of citation is unified is quality %.Do not give the amount of special description, value unit meets industry general provision and usual usage, it will not go into details.

One. the smelting process of described 21-10Mn7Mo welding wire, wherein, the chemical composition quality % of 21-10Mn7Mo steel ingot should meet: carbon C≤0.10, silicon Si≤0.8, manganese Mn5.5-8.0, phosphorus P≤0.030, sulphur S≤0.020, nickel 9.0-11.0, chromium Cr19.0-22.0, molybdenum Mo0.5-2.0, or/and surplus is iron Fe and inevitable impurity, or/and, Mn/Mo ratio controls between 7-7.5, this reasonable disposition molybdenum manganese composition than effect comprise the problem effectively avoiding manganese metal in the easy scaling loss of reflow process.

Specifically describe metal molybdenum, the effect of manganese element in stainless steel, acting as of other compositions is generally known, repeats no more.

1. the effect of metal molybdenum Mo element.

1.1. molybdenum is to stainless microstructure and heat treated effect

Molybdenum has two important effects as alloying element to steel and other alloys, namely improves intensity and erosion resistance.Molybdenum can be solid-solution in ferrite, austenite and carbide in steel, and it is the element reducing austenite phase field; There is refinement steel microcosmic crystal grain and reach the effect of refined crystalline strengthening, when molybdenum content is lower, forming the cementite of compound with iron, carbon; Then forming its high rigidity alloy carbide-MoC/Mo2C when content is higher, is the strengthening phase in steel; Molybdenum improves the hardening capacity of steel, and it is strong that it acts on comparatively chromium, and be slightly poorer than manganese; Molybdenum improves steel belt roof bolt stability.When existing as single alloying element, increase steel belt roof bolt fragility; With chromium or manganese etc. and when depositing, molybdenum reduces again or restrains the temper brittleness because other elements cause.

1.2 molybdenums are to the effect of stainless mechanical property

Molybdenum has solution strengthening effect to ferrite, can also form Precipitation phase in stainless steel, improves the intensity of steel, also improves the stability of carbide simultaneously, thus improves the intensity of steel; Molybdenum plays advantageous effect to improving the ductility of steel and toughness and wear resistance; Because molybdenum makes the softening and recovery temperature after working hardening and recrystallization temperature improve, and the ferritic creep resistance of strong raising, effective suppression cementite under gathering, promote the precipitation of alloy carbide, thus the effective especially alloying element improving steel heat resistance is become, molybdenum can improve the mechanical behavior under high temperature of austenitic stainless steel, and such as lastingly, the performance such as creep all can obtain larger improvement.

1.3 molybdenums are to the effect of stainless physical chemistry and processing performance

Can make steel surface passivation in reductive acid and strong oxidizing property salts solution, therefore molybdenum generally can improve the etch resistant properties of steel, prevents the spot corrosion of steel in chloride soln; Time molybdenum content higher (> 3 quality %), the oxidation-resistance of steel is worsened; The steel being no more than 8 quality % containing molybdenum still can be forged, roll, but when content is higher, steel increases hot worked resistance to deformation.

In summary, molybdenum is formed and stable ferrite expand the element of ferrite phase region.

But adding of molybdenum makes the high temperature hot deformation resistance of steel increase, usually there is a small amount of delta ferrite in addition in steel and thus do not contain molybdenum steel for poor containing molybdenum stainless hot workability ratio, and molybdenum content is higher, hot workability is worse; Molybdenum also promotes intermetallic phase in austenitic stainless steel, such as σ phase, κ phase, the precipitation equal with Laves, all can have a negative impact, particularly cause plasticity to the solidity to corrosion of steel and mechanical property, and toughness declines.

For the austenite structure making austenitic stainless steel keep single, along with the increase of molybdenum content in steel, the content of austenite former also wants corresponding raising, to keep the balance in steel between ferrite and austenite former, therefore after this case adds molybdenum in austenitic stainless steel, the content also corresponding raising of manganese.General known described austenite former refers to nickel, nitrogen, manganese etc.

2. the control of manganese metal Mn element

Manganese is similar to nickel for austenitic effect.But the vital role of manganese does not lie in formation austenite, but be that it reduces the critical quenching rate of steel, increase austenitic stability when cooling, suppress austenitic decomposition, the austenite formed under making high temperature is remained to normal temperature.

In the corrosion resistance nature improving steel, the effect of manganese is little, and experiment shows, as the manganese content in steel changes from 0 to 10.4 quality %, the corrosion resistance nature of steel in air and acid can not be made to occur significantly to change.

Further, add Mn and more nitrogen can be made to dissolve in austenite, and nitrogen is strong austenite former, containing the nitrogen of 0.25 quality %, forms the nickel that austenitic ability is equivalent to 7.5 quality %.

Improve the content of manganese in welding wire, except desoxydatoin, can also close with sulfuration and generate manganese sulfide (MnS), and be removed (that is: desulfurization), therefore the tendency of the thermal crack caused by sulphur can be reduced, the intensity of welding wire can be improved simultaneously.

But the content of manganese needs effectively to control, when the too high levels of manganese easily makes material solidification or applied at elevated temperature process in which materials organize thick, increase the fragility of material.

3. the material chemical composition quality % of this case 21-10Mn7Mo and prior art contrasts, in table 1.

See Fig. 1-5, test shows, is suitable for determining addition, and form new alloy, after welding wire made by such alloy, its intensity can significantly improve.

Two, the description of smelting process

1. smelt 21-10Mn7Mo steel ingot, its chemical composition quality % should meet as follows,

It comprises: carbon C≤0.10, silicon Si≤0.8, manganese Mn5.5-8.0, phosphorus P≤0.030, sulphur S≤0.020, nickel 9.0-11.0, chromium Cr19.0-22.0, molybdenum Mo0.5-2.0.

Further, or/and Mn/Mo ratio controls between 7-7.5;

All right, Mn/Mo is than controlling as 7-7.1, or 7.2-7.3, or 7.4-7.5.

Or, described 21-10Mn7Mo steel ingot, its chemical composition quality % is by carbon C≤0.10, silicon Si≤0.8, manganese Mn5.5-8.0, phosphorus P≤0.030, sulphur S≤0.020, nickel 9.0-11.0, chromium Cr19.0-22.0, molybdenum Mo0.5-2.0, or/and surplus is iron Fe and inevitable impurity composition.

Further, or/and Mn/Mo ratio controls between 7-7.5.

All right, Mn/Mo is than controlling as 7-7.1, or 7.2-7.3, or 7.4-7.5.

Described 21-10Mn7Mo steel ingot, its purity and homogeneity, on the processing of 21-10Mn7Mo welding wire and the impact of welding below very large, in smelting technology, corresponding technological measure should be had for ensure 21-10Mn7Mo steel ingot purity and homogeneity for this reason.

2. the basic skills of smelting adopts electric arc furnace smelting+esr (ESR), and concrete steps comprise:

2.1 first steps smelted, adopt electric arc furnace Returning blowing keto technique to smelt esr electrode.

The first step of described smelting, wherein, molten steel temperature reaches 1400-1600 DEG C, at high temperature realizes high chromium steel liquid decarbonization and protecting chromium.

2.2 second steps smelted, adopt esr to carry out refining.

Further, the technological process of the first step of smelting successively: fettling, charging, melting period, oxidation period, reduction period, tapping, casting resmelting electrode.

2.1.1 fettling: fettling material application bittern stirs, and forbids to mix with clear water.

Fettling material 100 object magnesia powders 65%, all the other use the magnesia grain of 1-5mm granularity.

Fettling main points: furnace temperature is high, operation is fast, it is thin to mend layer.

2.1.2. feed:

2.1.2.1 loading sequence: in lime, small powder, bulk material, small powder, surrounding, small powder is or/and small powder.

Generally known: small powder size is about 100*100*100mm, middle material size is about 100*100*100 ~ 250*250*250mm, and aniseed size is about 250*250*250 ~ 600*350*250mm.

2.1.2.2 cloth requires: pine (2) height of center is tightly gone up at (1) end, and surrounding low (3) Ni, Mo are placed on furnace high-temperature district, but can not be placed on arcing district, in order to avoid scaling loss.

2.1.2.3 furnace charge requires: allow to add appropriate foundry returns, forbid to be mixed into the harmful elements such as Pb, Sn in raw material, raw material must clean drying.

Enter furnace charge and include but not limited to it is pure iron length ≯ 400mm, square billet length ≯ 500mm, steel ingot ≯ 3.

2.1.3. melting period

A. task comprises melting period: (1) be fused into the de-part phosphorus (3) of molten steel (2) prevent air-breathing, metal volatilize (4) reach temperature required.

B. the measure improving burn-off rate comprises: the outer preheating scrap of (1) oxygen blast combustion-supporting (2) stove and other furnace charges.

C. the measure of control of melting period comprise:

C1. the control of electrode: electrode wears the band impedance of well stage, adopts high-power power transmission; Add lime material, fluorite material, for stable arc in batches.

C2. the control of the quantity of slag before oxygen blast: melting period the quantity of slag account for 5 ~ 7% of molten steel amount.Generally known, the quantity of slag represents by the thickness of slag blanket.

C3. oxygen blown control: start oxygen blast when furnace temperature reaches more than 950 DEG C, oxygen pressure-controlled is being not more than 0.4MPa.Further, oxygen pressure is unsuitable excessive, and oxygen blast will be noted preventing from blowing bad furnace wall, prevents furnace charge bridging, splash.Furnace charge of controlling well caves in direction, reduces to seethe with excitement greatly, prevent broken Electrode.

C4. the control of dephosphorization: load melting later stage, when molten steel carbon content meets preset value, carry out low temperature dephosphorization, add lime or broken ore in good time, fire door flows slag dephosphorization automatically;

The load melting later stage quantity of slag controls: add lime or broken ore, the quantity of slag accounts for the ratio control of molten steel amount for being equivalent to 3% ~ 4%, and this operation also can be that general technology realizes, and repeats no more.

C5. after furnace charge all melts, stir and choose melting down sample analysis, continuous power transmission after sampling also adjusts slag, for oxidation period creates conditions.

2.1.4. oxidation period

2.1.4.1 oxidation period task: (1) dephosphorization, decarburization; (2) degasification: comprise denitrogenate, dehydrogenation; (3) inclusion in molten steel is removed.

2.1.4.2 oxidation period order of operation

(1) decarburization after first dephosphorization; (2) temperature: high temperature after first low temperature; (3) slag making: first how rear few; (4) feed, first adds oxygen blast after ore.

2.1.4.3 oxidation period measure of control

A. oxidation period slag control: by adding ore, lime in time, control slag flowing.Concrete measure comprises: the quantity of slag of a. slag controls be equivalent to 2% ~ 3% of molten steel amount; B. slag basicity controls be equivalent to 2.5 ~ 3; C. sinter thickness controls be equivalent to 40mm ~ 60mm.Thus, ensure that slag has the good fluidity of expection.

A1. add the opportunity of ore and the control of amount described in: add ore in batches, often criticize ore deposit amount and be set to 3-4kg or 4-5kg, interval 3-4 minute or 4-5 minute between adjacent batch.

Add ore technology main points to comprise high temperature Jia Kuang, add and add slowly less, high-boiling, flows slag automatically in batches.

Thus, can come control temperature and slag flow velocity by suitably adding ore, described ore is as fluorite.Utilize ore to heat up slow feature, add ore and be more conducive to dephosphorization, constantly add ore and can keep (FeO) 10 ~ 20% in slag, automatically flow slag or skim phosphorus is removed in a large number.Solve molten steel dephosphorization and slag flowability problem thus.

A2. oxygen behind first ore deposit is adopted, when dephosphorization reaches requirement, oxygen decarburization.Oxidation period, total decarburized amount was no less than 0.3%.

2.1.4.4 sampling analysis C, P, Cr, Ni, Mo etc., then killing Fe-Si powder 15kg immediately after oxygen blast, push away slag and stir, insert Al1 ~ 4kg/t.

2.1.4.5 the extra low carbon ferrochromium added, described extra low carbon ferrochromium can add being baked to 600 ~ 700 DEG C, adds fashionablely should remove the foreign material be clipped in wherein, broken end etc., and should weigh and weigh.

2.1.4.6 be oxidized latter stage, reach when carbon content is reduced to meet tapping requirement lower than production specification lower limit 0 ~ 0.08%, phosphorus, stop oxidation operation, start only to seethe with excitement.In this process, control end point carbon well, prevent molten steel peroxidation.

2.1.5 reduction period, main task is deoxidation, desulfurization during this period; Final adjusting component meets the demands; Adjustment molten steel temperature, normally pours into a mould.The reasonable coordination of Fe content in the aforesaid material composition of reason, comprises in the good result of this performance: can effectively reduce the tendency being caused thermal crack by sulphur, thus improves the intensity of welding wire.

2.1.5.1 key control point:

(1) add rapidly lime, fluorite (3:1) after removing oxidation sludge, make thin slag, after thin slag is formed, add lime more in batches, adjustment slag, and add electrolytic manganese.

(2) employing Ca-Si powder, Al powder carry out diffusive deoxidation, and the white rear fully stirring of slag is got Duplicate Samples and carried out total analysis.

(3) with small power insulation reduction, before tapping, available high-power intensification is to ensure tapping temperature and the good mobility of slag.

(4) reduction period should check slag situation in time; Timely thermometric, controls the basicity of slag and mobility well, keeps white slag to tapping, the reducing atmosphere in control stove.

(5) tapping sample alloying constituent is prescribed a time limit lower than under production specification, adds alloy, could tap after stirring sampling analysis is qualified.

2.1.6. to tap key control point

(1) 5 minutes must be greater than to the tapping time after adding alloy, also need when add-on is large to extend the tapping time, ensure all to melt.

(2) tapping inserts Al0.4 ~ 0.5 ㎏/t, tapping temperature 1580 ~ 1600 DEG C.

2.1.7. cast resmelting electrode key control point

(1) calm 3 ~ 7 minutes are wanted after tapping, depending on liquid steel temperature height.

(2) control pouring temperature 1450 ~ 1480 DEG C, casting rate 110 ~ 150kg/s well, accomplish not magic flower, not conjunctiva, do not cut note.

(3) open stream and want large, when molten steel rises to ingot body more than 1/3, suitably can entirely flow fast note.

To sum up, in alloy melting each alloying element joining day and recovery rate in table 1

2. the second step smelted, adopts esr to carry out refining.

This case adopts both arms alternately continuous stripping formula esr equipment, realizes continuous stripping, wherein,

Steel ingot is set to elongated ingot shape, and the ratio of steel ingot diameter Di and steel ingot length is 1:5 or 1:5.3.

Crystallizer diameter D _knotmeet with the relation of Di steel ingot diameter: D _knot=1.03*Di.

Crystallizer height H and crystallizer diameter D _knotrelation meet: H ≈ (1.5 ~ 2.0) * D _knot.

Electrode diameter d _polemeet with the relation of electrode length: stacking factor meets d _pole/ D _knot.

The control of 2.1 parameters

2.1.1 about slag system:

The selection of slag system: the wherein selection of slag system fusing point, be preferably and select the fusing point of slag system low 100 ~ 200 DEG C of the fusing point of proportion molten steel to be advisable, the plasticity of steel ingot is better thus.

Also have, consider that there is enough ratio resistance, good mobility (viscosity), the unstable oxide content that appraises at the current rate in slag controls lower (as FeO, SiO2, MnO etc.) as far as possible, its basicity, surface tension and ventilation property should be considered, the selection of slag system also should consider its economy and security, and these can be solved by general measures, how not to repeat.

The process acts of esr slag wherein, not only has the resistance heater effect as thermal source, also has and forms the effect of skull for ingot casting plasticity.

The metallurgy action of esr slag wherein, not only can realize the purifying functions to steel, can also realize the oxidation and induction effect to element.

This case slag system includes but not limited to following selection: the slag ANF-8 selecting first slag system CaF2-Al2O3-CaO slag system, proportioning is CaF2:Al2O3:CaO=60%:20%:20%

Described slag melting point is equivalent to about 1250 DEG C, uses the feature that this slag melting point is lower, for esr ingot casting, can reach spindle any surface finish good, shaping good technique effect.

Also use the ability characteristic that this slag has certain desulfurization, deoxidation, removal non-metallic inclusion, and this slag is when high temperature reaches 600 ~ 1200 DEG C, the intensity of slag crust and plasticity is feature all better, and when selecting thus to can be implemented in stripping or lift crystallizer, slag crust not easily breaks.

Depth of slag bath H _slagwith pole distance H _interpolarrelation coincidence formula: H _interpolar=0.87H _slag-31.4

2.1.2 the quantity of slag: the experimental formula that the quantity of slag quoted calculates can be: G _slag=(4 ~ 5%) G _ingot;

Or calculation formula can also be: G=pi/2 × D ²h σ.

Wherein, D represents crystallizer diameter, unit rice; H represents slag blanket height, unit rice; σ represents slag ratio weight.

Generally known, slag resistance size can be known from the size of the quantity of slag.

The usual thickness with slag blanket represents the quantity of slag, if slag thickness increases, then electrode insertion depth increases, and decreases the oxidation of electrode, thus oxide inclusion in steel is reduced.

If with the increase that slag is thick under the condition that crystallizer, electrode size are certain, productivity can be reduced, increase power consumption.

2.1.3 electric current is smelted: under the prerequisite that slag system and voltage are determined, choosing of melting current, the requirement of Main Basis burn-off rate and metal pool shape and determining.It is 8000 peaces that the best that this case is selected smelts electric current.

Following relational expression is met: I between general known electric current and crystallizer diameter _eSR=k ₀dm

Wherein, k ₀-being called crystallizer electric current per unit length, its value is chosen as 15-25A/mm.This value choose Main Basis pool depth size and different slag system.K ₀be worth larger, molten bath is darker.

Under the condition that operating voltage is certain, along with electric current increases, metallic element scaling loss amount reduces, and this is because embedding depth of electrode increases, and improves caused by oxidized condition.And electric current continues to increase, the transmission of oxygen is more convenient, and melting loss of elements amount increases on the contrary, is all disadvantageous to the removal of inclusion and low multiple quality simultaneously.

2.1.4 operating voltage: melting operating voltage, also known as fire door voltage or effective operating voltage, refers to the voltage between electrode tip and low crystallizer.The formula usually quoted is:

Operating voltage V _work=0.6D _knot+ 26 wherein: D _knotunit is cm.

2.2 target component

2.2.1 controlled melting speed and ingot diameter ratio are no more than 1, for ensureing ingot crystal quality.

Metal pool depth H _gold: the metal pool degree of depth directly affects product metallurgical quality, and molten bath is more the shallow flat crystallization that just more easily generation axis is large, is mingled with more favourable to removal.

H _goldlarger, its crystallization velocity is slower, and secondary dendrite arm spacing just increases, then easily cause microsegregation and the low power segregation defects of chemical composition.

Usual H _gold1/2 ~ 1/3 of crystallizer diameter.Burn-off rate V mainly by control electrode in actual production _moltencontrol the metal pool degree of depth, relational expression: V _molten=(0.7 ~ 0.85) D _knot, V in formula _moltenunit is kg/h.

The measure of control of cooling:

Between steel ingot and crystallizer, there is gap, for the formation of slag crust.

Described slag crust thickness is 1 ~ 2mm, and thickness of the slag crust uniformity.

The measure of thickness of the slag crust uniformity: cooling intensity controls as cooling is gentle, and cooling should not change suddenly, in order to avoid cause slag crust thickening or thinning suddenly, ensures that the slag crust layer forming thickness uniformity between steel ingot and crystallizer constructs thus.

Crystallizer leaving water temperature(LWT) controls at 40-50 DEG C or 50-60 DEG C, and inflow temperature should lower than 30 DEG C.Preferred employing circulation soft water, water rate control is at 30 ~ 45m ³/ t.

The selection of circulation soft water can avoid mineral deposits, in crystallizer, form incrustation scale.

Water mold is the important process feature that esr is different from general smelting process.Generally known, the size of cooling intensity, crystalline texture and grain orientation are had a certain impact, if but increase cooling intensity, it is little that chill but increases, arranging slag crust thickness is 1 ~ 2mm, and it has good heat insulating function, makes cooling intensity be difficult to decisive role to crystalline texture thus.It should be noted that in smelting process, cooling intensity should not change suddenly, in order to avoid cause slag crust thickening or thinning suddenly, avoid surface of steel ingot to produce annular slag runner.

Summary technological process, smelt and complete desulfurization task, compare with general melting method, one of most important advantage of esr to make seasoning metal carry out very strong desulfurization.

The reaction of esr desulfuration all occurs in following several stages: electrode melting end-molten drop formation stages; Metal drop enters the metal pool stage through slag blanket; Physical-chemical reaction on metal pool and slag bath interface; Sulphur shifts in slag in opposite directions gas phase.

Metal pool and slag bath interracial contact specific area little, but due to the reaction times longer, so also play a role to desulfuration.

Smelt and also complete (hydrogen, nitrogen, oxygen) task of degassing, the hydrogen in steel not only can make steel produce hydrogen embrittlement, steel also can be made to produce white-spot defects, reduce tensile strength, plasticity and the relative reduction in area of steel.

Facts have proved that esr metal hydrogen content is relevant with following factor:

The trade mark of seasoning metal; Slag composition and slag charge dry condition; Remelting atmosphere.

Smelt the oxidation and the reduction that also complete alloying element, in reflow process, in steel, active element often loses because of oxidation.Aforesaid smelting process effectively prevent active element oxidation, solves the important metallurgical problems of esr.Such as:

In the electroslag remelting process process of this case, oxygen enters slag and molten steel by following approach:

A. in the oxygen dissolved in original electrodes steel and steel, unstable oxide releases oxygen at pyrolytic decomposition;

B. electrode surface oxide skin brings the oxygen in slag into;

C. the oxygen that in slag, unstable oxide FeO, MnO, SiO2, Cr2O3 etc. are contained;

D. the oxide compound that appraises at the current rate in slag transmits oxygen supply effect, and as suboxides such as Fe, Mn, Cr in slag, the oxygen in slag bath Surface absorption air, forms high oxide.The high oxide of these elements, at slag bath and metal pool interface, release oxygen, become suboxide, oxygen thus enter in steel, this reaction is a working cycle.

Further, reduce the measure of the oxidisability of slag: a. reduces the source of oxygen, electrode wants abundant deoxidation, scale removal; Slag, reduces FeO, the MnO etc. in slag; Protection of inert gas.B. reflow process deoxidation: add ferrosilicon, silico-calcium, aluminium deoxidation.

Further, technological measure when current control is unstable

1. suitable increase setting electric current (restriction: I≤permissible value)

2. voltage (restriction: U is suitably reduced _eSR>=minimum value)

3. Hs (i.e. the quantity of slag) is suitably increased

Further, the technological measure adopted time Ingot Surface Quality bad (slag runner is serious)

1. electric current (when electric current is excessive, namely U/I is too small, and Lem is too small) is suitably reduced

2. the quantity of slag (quantity of slag is excessive) is suitably reduced

Further, burn-off rate is excessive, the technological measure adopted when molten bath is too dark

1. electric current is reduced

2. voltage is reduced

3. the quantity of slag is reduced

The control of raw materials for metallurgy

1) requirement of consumable electrode: surface should be cleaned, dry, be mingled with without mud, nothing.

2) chemical composition of iron aluminium bar must meet C ≯ 0.06%, Al:10-15%

3) fluorite: CaF is given birth to ₂>=95%, SiO ₂≤ 5%, granularity≤5mm, block fluorite needs to rinse well with water before using.

4) purification fluorite: SiO ₂≤ 0.5%, S≤0.1%, granularity≤5mm.

5) aluminum oxide powder: Al ₂o ₃>=98%, SiO ₂≤ 1.0%.

6) lime block: CaO >=90%, S≤0.4% should use after toasting under red heat state.

7) titanium dioxide powder adopts technical pure.

8) slag charge should keep dry clean, needs through 700-800 DEG C of baking 3 hours before using.Limestone block should toast separately.

9) Conductive Slag: TiO ₂: CaF ₂=55:45, forms through refining, and Conductive Slag should keep clean dry.

The method of purification of fluorite in raw materials for metallurgy

1) slag charge: fluorite block or Fluorspar Powder are through 600-800 DEG C of baking 2-3 hour, and powdery fluorite requires to have a power failure stirring once every half an hour.

2) purification fluorite adopts the melt cinder starting the arc.Change slag hearth fusing starting the arc melt cinder, when changing slag, allow to insert Al100-150 gram, for the situation of satisfied reply slag splash.

3) the preferred method of purification process slag charge is: spare no effort to add less; Reinforced opportunity is: often criticize after slag charge adds, and meets bright (bright in the industry universal industrial common saying), then adds virgin material.

4) according to iron aluminium bar quality condition, allow in slag charge, add appropriate dry aluminium powder, stir use.

5), after slag charge adds, refining 5-10 minute must be carried out.

The working method of electroslag furnace

1) unimpeded in water-cooling system, crystallizer, end water tank, change slag hearth, without infiltration, drainage, can be smelted when equipment operation is normal.

2) the residual steel on end water tank, crystallizer, residue should be rejected and totally made it smooth.

3) to note having enclosed asbestos twine, crystallizer is steadily put well, in case break arc bleed-out.Asbestos twine will through 80-120 DEG C, baking in more than 8 hours.

4) consumable electrode just will to be gone up on jail, and adjustment electrode, makes electrode be deep in crystallizer, along the position of 40-60mm on end water tank.

5) after the good slag of useization slag hearthization slag impouring slag spoon, when melt cinder injects crystallizer, action is wanted rapidly, accurately.Forbid slag ladle to contact with crystallizer with consumable electrode, in case discharge breakdown crystallizer simultaneously.

6) starting the arc, powers on request, manual operation 5-10 minute, can proceed to automatically after current stabilization.

7) reflow process will note adjustment consumable electrode and crystallizer gap at any time.As found, crystalliser feet is struck sparks, and should process in time.Allow the way adopting end water tank and crystallizer short circuit if desired, ensure and continue to smelt

8) feeding adopts continuity and discontinuity to combine, and total feeding time is not less than 10 minutes.When current value is zero, have a power failure and promote electrode.

9) the de-ingot time: have a power failure and can take off ingot after 20 minutes.

So far, the smelting process of this case electric arc furnace smelting+esr (ESR) possesses following special result:

21-Mn7Mo is at H1Cr ₂1Ni10Mn ₆basis on the addition of Mo and Mn and obtain, adding Mo in steel can crystal grain thinning, makes steel have uniform fine grained texture.And in order to control the impurity component smelted in STEELMAKING PRODUCTION, the interpolation of Mn adopts electrolytic manganese, manganese content is that the interpolation of 97.25%, Cr element adopts purity to be the extra low carbon ferrochromium of 99.22%.Adding of Ni element adopts purity to be the electrolytic nickel of 99.98%, molybdenum element also adopt purity be 99.96% metal molybdenum, the interpolation of element silicon adopts purity to be the industrial silicon of 99.6%.Therefore the possibility that impurity adds is decreased from original aspect.On the other hand, purify by the method for esr again after adopting the first ingot of arc smelting.Esr industry has that purity is high, sulfur-bearing is low, non-metallic inclusion is few, chemical composition is even and the feature of ingot structure's even compact.Therefore, the cast metals of the 21-Mn7Mo obtained by the above-mentioned control of smelting aspect and the selection of technique has good structure property, ensure that the processing quality in later stage.

The comparison of chemical composition

Following table is that the chemical composition that 21-Mn7Mo adopts arc smelting and electric arc furnace smelting+esr two kinds of methods to smelt contrasts.

Adopt electric arc furnace+electric slag refusion and smelting and electric arc furnace smelting 21-10Mn ₇the chemical composition contrast of Mo

The content of carbon reduces 33% than simple electric arc furnace smelting as can be seen from the above table, and the content of sulphur reduces 90%, therefore in processing characteristics, has had obvious improvement compared with simple electric arc furnace.

The comparison of metallographic structure, see Fig. 1-5, the steel ingot illustrating the 21-10Mn7Mo smelted from electric arc furnace smelting and electric arc furnace smelting+esr two kinds of methods respectively intercepts metallographic specimen, at electronic scanning electricity Microscopic observation after polishing, corrosion.

Can find out by observing the tissue of electric arc furnace smelting and the tissue of electric arc furnace+esr, after esr, organizing its crystal grain relatively little, there is no large-sized inclusion, and precipitate be also relatively little.

The block inclusion of the black having size relatively large in the tissue of simple electric arc furnace smelting, has the white point assembled in the segregation of obvious Mn in block, finds that this thing is MnS by XRD analysis in the inclusion by the scanning discovery black to Mn Elemental redistribution.And by the scanning discovery to the distribution of the Mn element of electric arc furnace+esr and the distribution of Mo element, Mn and Mo element be all well-proportioned distribution in the base, there is no segregation phenomenon.Illustrate containing the MnS inclusion of large-size in the ingot structure of electric arc furnace smelting thus, and after esr is purified, organize purer and alloying elements distribution is even.

Therefore illustrate and adopt the mode of electric arc furnace+electric slag refusion and smelting (ESR) can improve the homogeneity of composition of raw material and purity and organize dense, crystal grain is tiny.

The clean even compact of tissue is conducive to the raising of mechanical property.Because there is the inclusion of large-size in tissue, have matrix and significantly isolate effect, and easily produce tiny crack near large-sized inclusion, have serious impact to mechanical property, its mechanical property can be caused lower.Intermetallic compound Cr in the tissue after esr ₂ni ₃and Fe ₃ni ₂particularly MoNi ₄separate out with the particle of small and dispersed, matrix is served to the effect of dispersion-strengthened.

After the preferred embodiment described in detail, be familiar with this technology personage can clearly understand, do not departing under claim described in this case and spirit and can carry out various change and amendment, and the present invention is not also limited to the embodiment of illustrated embodiment in specification sheets.

Claims (10)

1. the smelting process of a 21-10Mn7Mo steel ingot, comprise first step electric arc furnace Returning blowing keto technique to smelt esr electrode and second step esr and carry out refining, wherein, described steel ingot chemical composition quality % comprises: carbon C≤0.10, silicon Si≤0.8, manganese Mn5.5-8.0, phosphorus P≤0.030, sulphur S≤0.020, nickel 9.0-11.0, chromium Cr19.0-22.0, molybdenum Mo0.5-2.0; Mn/Mo ratio controls at 7-7.5;

Or, described steel ingot chemical composition quality % is by carbon C≤0.10, silicon Si≤0.8, manganese Mn5.5-8.0, phosphorus P≤0.030, sulphur S≤0.020, nickel 9.0-11.0, chromium Cr19.0-22.0, molybdenum Mo0.5-2.0, and surplus is iron Fe and inevitable impurity composition; Mn/Mo ratio controls at 7-7.5;

The technological process of described first step is successively: fettling, charging, melting period, oxidation period, reduction period, tapping, casting resmelting electrode;

The selection of slag system in the technological process of described second step: the slag ANF-8 selecting first slag system CaF2-Al2O3-CaO slag system, proportioning is CaF2:Al2O3:CaO=60%:20%:20%.

2. the smelting process of steel ingot according to claim 1, wherein, in described second step, select the fusing point of slag system should the fusing point of proportion molten steel low 100 ~ 200 DEG C; Or/and described slag melting point is equivalent to 1250 DEG C; The selection of slag system: the slag ANF-8 selecting first slag system CaF2-Al2O3-CaO slag system, proportioning is CaF2:Al2O3:CaO=60%:20%:20%.

3. the smelting process of steel ingot as described in one of claim 1-3, wherein, in described second step, controlled melting speed and ingot diameter ratio are no more than 1; The measure of control cooled in described second step: there is between steel ingot and crystallizer the clearance configurations for the formation of slag crust; It is 1 ~ 2mm that the gap of described slag crust can meet the slag crust thickness formed, and thickness of the slag crust uniformity.

4. the smelting process of steel ingot as described in one of claim 1-3, wherein, in described second step thickness of the slag crust uniformity technological measure in: cooling intensity controls as cooling is gentle, and cooling should not change suddenly; Stating crystallizer leaving water temperature(LWT) in second step controls at 40-50 DEG C or 50-60 DEG C, and inflow temperature should lower than 30 DEG C; Or/and quote circulation soft water, water rate control is at 30 ~ 45m ³/ t.

5. the smelting process of steel ingot as described in one of claim 1-4, wherein, in fettling step: fettling material application bittern stirs, not handy clear water stirs; Or/and, in charging procedure: Ni, Mo are placed on the region of relatively-high temperature in stove, arcing district can not be placed on; The control of electrode of described melting period is: electrode wears the band impedance of well stage, adopts high-power power transmission; Or/and, add lime material, fluorite material, for stable arc in batches; Or/and, melting period oxygen blown control: start oxygen blast when furnace temperature reaches more than 950 DEG C, oxygen pressure-controlled is being not more than 0.4MPa; Or/and, melting period dephosphorization control: in the load melting later stage, when molten steel carbon content meets preset value, carry out low temperature dephosphorization, add lime or broken ore in good time, fire door flows slag dephosphorization automatically.

6. the smelting process of steel ingot as described in one of claim 1-5, wherein, described in add the opportunity of ore and the control of amount: add ore in batches, often criticize ore deposit amount and be set to 3-4kg or 4-5kg, interval 3-4 minute or 4-5 minute between adjacent batch.Described oxidation period is dephosphorization, decarburization; Degasification: comprise denitrogenate, dehydrogenation; Remove inclusion in molten steel; Its oxidation period dephosphorization, decarburization order be first dephosphorization, rear decarburization; Temperature Control sequence is: first low temperature, rear high temperature; Slag making order is: first volume, on a small quantity rear; Feed order is, first adds ore, rear oxygen blast.Oxidation period slag control: by adding ore, lime in time, control slag flowing; Or/and the quantity of slag of slag controls be equivalent to 2% ~ 3% of molten steel amount; Or/and slag basicity controls be equivalent to 2.5 ~ 3.

7. the smelting process of steel ingot as described in one of claim 1-6, wherein, sinter thickness controls be equivalent to 40mm ~ 60mm.In reduction period, lime, adding of fluorite add rapidly after removing oxidation sludge, and ratio is 3:1; Produce thin slag, after thin slag is formed, then add lime in batches, adjustment slag, and add electrolytic manganese; Or/and employing Ca-Si powder, Al powder carry out diffusive deoxidation, after slag is white, fully stirs, get Duplicate Samples and carry out total analysis; Or/and insulation reduction step selects small power to heat up, and can select high-power intensification before tapping.Wherein, in the control of tapping step: after adding alloy, the time between tapping should be relatively long, controls be greater than 5 minutes; Or/and Al0.4 ~ 0.5 ㎏/t is inserted in tapping; Or/and tapping temperature selects 1580 ~ 1590 DEG C or 1590 DEG C-1600 DEG C.

8. the smelting process of steel ingot as described in one of claim 1-7, wherein, described first step, wherein, molten steel temperature reaches 1400-1600 DEG C, at high temperature realizes high chromium steel liquid decarbonization and protecting chromium.

9. the smelting process of steel ingot as described in one of claim 1-8, wherein, the control of cast resmelting electrode: cast controls after tapping opportunity, leave standstill 3 ~ 7 minutes, whether measuring tempeature meets pouring temperature condition; Or/and controlling pouring temperature is 1450 ~ 1460 DEG C or 1460 DEG C ~ 1470 DEG C or 1470 DEG C-1480 DEG C.

10. the smelting process of steel ingot as described in one of claim 1-9, wherein, casting rate is 110 ~ 120kg/s; Or 120 ~ 130kg/s or 130 ~ 140kg/s, or 140 ~ 150kg/s; Or/and opening stream can more greatly, and when molten steel rises to ingot body more than 1/3, or full stream is noted soon; Wherein, Mn/Mo is than controlling as 7-7.1, or 7.2-7.3, or 7.4-7.5.

Or/and in described second step, steel ingot is set to elongated ingot shape, the ratio of steel ingot diameter Di and steel ingot length is 1:5 or 1:5.3; Crystallizer diameter D _knotmeet with the relation of Di steel ingot diameter: D _knot=1.03*Di; Crystallizer height H and crystallizer diameter D _knotrelation meet: H ≈ (1.5 ~ 2.0) * D _knot; Electrode diameter d _polemeet with the relation of electrode length: stacking factor meets d _pole/ D _knot; Arranging smelting electric current is 8000 peaces;

Or raw materials for metallurgy adopts the interpolation of Mn element to adopt Fe content to be the electrolytic manganese of 97.25%, and the interpolation of Cr element adopts purity to be the extra low carbon ferrochromium of 99.22%; Adding of Ni element adopts purity to be the electrolytic nickel of 99.98%, molybdenum element also adopt purity be 99.96% metal molybdenum, the interpolation of element silicon adopts purity to be the industrial silicon of 99.6%.