CN101654742A - Electroslag remelting slag system with low hydrogen permeability, preparation method and using method thereof - Google Patents

Abstract

The invention discloses an electroslag remelting slag system with low hydrogen permeability, and a preparation method and a using method thereof. The slag system is prepared from the following chemical compositions in percentage by weight: 45 to 50 percent of CaF2, 10 to 15 percent of CaO, 30 to 35 percent of Al2O3, 5 to 10 percent of SiO2, and 5 to 10 percent of MgO, wherein the MgO is adopted toreplace partial CaO. The preparation method is to crush the compositions into particles after melting, and bake the particles. The using method adopts pre-melting slag and argon protection to carry out electroslag remelting. Compared with the prior art, the slag system and the methods have the advantages that: the slag system has low hydrogen permeability, can effectively reduce the hydrogen content in steel in the remelting initial stage to ensure that the hydrogen content in the steel in the normal remelting stage is maintained at a lower level, and the hydrogen content in the remelted steel is less than 1.5ppm.

Description

A kind of electroslag remelting slag system with low hydrogen permeability and preparation method thereof and using method

Technical field

The present invention relates to the field of electroslag metallurgy, belong to electroslag remelting slag especially, adopt MgO instead of part CaO, regulate the composition of slag system in right amount, make slag system possess low hydrogen penetrating quality; Adopt pre-melted slag and argon shield measure to reduce after the remelting hydrogen richness in the steel simultaneously.

Background technology

Since electroslag remelting technique is born, be the important means of producing special material always.Esr process forms the stage at the electrode tip drop, and drop passes the slag bath drippage stage, and steel-slag fully contacts, and nonmetallic inclusionsin steel is absorbed by slag.Liquid metal has been avoided reoxidizing under slag bath covers basically.The slag bath that rises forms the thin skull of one deck on the crystallizer inwall, not only make surface of steel ingot bright and clean, also plays insulation and heat-blocking action, and more heat is conducted to the bottom, helps steel ingot crystallographic orientation from bottom to top, improves the compactness of steel ingot.Therefore the electroslag process mainly is to play the effect of removing and control inclusion and control ingot solidification tissue.But the electroslag process often makes hydrogen richness increase in the steel easily.Therefore exist too high hydrogen richness easily to cause hydrogen embrittlement in the steel, control in the steel hydrogen richness and be very important problem.

The principal element that influences the hydrogen richness in the esr process steel has: the hydrogen rate of permeation of the hydrogen richness in the consumable electrode, the hydrate in the slag charge and hydrogen-containing compound, slag and the vapour content in the atmosphere etc.What at present, the hydrogen richness in the consumable electrode can be by means such as refining control is very low; Hydrate in the slag charge can remove by the control raw material and by baking.Present most of electroslag furnace all is to carry out remelting under atmospheric condition, therefore the moisture content in the atmosphere can't be controlled, and this moment slag system the hydrogen rate of permeation hydrogen richness in the steel is had conclusive effect, if adopt the low hydrogen permeability slag system then can effectively reduce hydrogen richness in the steel.

The major components that electroslag remelting slag contained has CaF ₂, CaO, Al ₂O ₃, SiO ₂Deng, CaO wherein is very easy to dissociate into Ca in the fused slag bath ²⁺And O ^2-, and O ^2-Very easily combine, thereby following reaction take place with water vapour in the ambient atmosphere:

O ^2-+H ₂O＝2(OH) ^-

And the formation hydroxyl, following reaction then can take place with metal ion in the steel in hydroxyl:

$2{\left(\mathrm{OH}\right)}_{\left(\mathrm{slag}\right)}^{-}+{\mathrm{Mi}}_{\mathrm{metal}}^{2+}=2{\left[H\right]}_{\mathrm{metal}}+2{\left[O\right]}_{\mathrm{metal}}+{\left[\mathrm{Mi}\right]}_{\mathrm{metal}}$

Thereby the hydrogen richness of steel grade is increased.Add the CaO constituent element in the slag and can reduce CaF in the slag ₂Ratio reduces the pollution of fluorine to environment, makes slag have certain sweetening power simultaneously.

The production of cold roll blank is generally adopted 40%CaF in the esr stage ₂-30%CaO-30%Al ₂O ₃The ternary slag system carries out esr, because of CaO constituent element composition in this slag system up to 30%, cause that hydrogen richness can reach more than the 10ppm in the remelting initial stage steel, hydrogen richness is also up to 5～7ppm in the normal remelting phase steel, require the later stage to carry out secular expansion hydrogen anneal process, this not only takies production unit, increases products production cost, the production cycle of having strengthened product simultaneously.

Through the Searches of Patent Literature; find one and relate to the patent that esr prevents to increase hydrogen: publication number is CN1078500; this patent mainly is to adopt the dry air protection to prevent to increase hydrogen to esr process; slag system there is not particular requirement; slag charge can be without baking; because of the electroslag remelting slag CaO constituent element composition mentioned in this patent up to 30%, slag charge can not be eliminated because of CaO without baking and absorb moisture to increasing the influence of hydrogen.

Summary of the invention

The technical problem to be solved in the present invention provides a kind of electroslag remelting slag system with low hydrogen permeability and preparation method thereof and using method, and this slag system can possess low hydrogen penetrating quality, can reduce in the reflow process content of hydrogen in the steel effectively.

For solving the problems of the technologies described above, a kind of electroslag remelting slag system with low hydrogen permeability of the present invention, the weight percent proportioning of its chemical ingredients is CaF ₂: 45～50%, CaO:10～15%, Al ₂O ₃: 30～35%, SiO ₂: 5～10%, MgO:5～10%.

At CaF2:40%, CaO:30%, Al ₂O ₃: on the basis of 30% ternary slag system, adopt MgO instead of part CaO, and add SiO ₂, regulate the composition of slag system in right amount, suppress the decomposition of CaO, the O in the control slag ^2-Concentration makes slag system have lower hydrogen rate of permeation, makes the lower level of hydrogen richness maintenance in the remelting steel.Simultaneously, this slag system also has lower Calcium Fluoride (Fluorspan) content, reduces fluoride pollution.

A kind of preparation method of electroslag remelting slag system with low hydrogen permeability, it may further comprise the steps:

1) by following weight percent proportioning preparation: CaF ₂: 45～50%, CaO:10～15%, Al ₂O ₃: 30～35%, SiO ₂: 5～10%, MgO:5～10%;

2) be equipped with pre-melted slag with the electric smelting legal system, slag electric current: 2000～4000A; Voltage: 46～48V; Tap to tap time: 45～55 minutes: mould cool time: 30～60 minutes;

3) be broken into after the melting granular.

In the described step 3), broken granular size is 3～10mm.

A kind of using method of electroslag remelting slag system with low hydrogen permeability, it may further comprise the steps:

1) weight percent of slag system composition is: CaF ₂: 45～50%, CaO:10～15%, Al ₂O ₃: 30～35%, SiO ₂: 5～10%, MgO:5～10%;

2) toasted in 4～8 hours through 800～900 ℃ of insulations before the use, to remove the moisture content in the slag;

3) ratio with ton steel 30～40kg adds baked bits in electroslag furnace;

4) top of crystallizer for electroslag furnace adopts argon gas to protect, and argon pressure is 0.15～0.25MPa, and flow is 5～6m ³/ h.

For other controlled variable of esr process, the present invention does not do any improvement, can adopt prior art, does not repeat them here.

The present invention adopts pre-melted slag and argon shield to carry out esr owing to adopt MgO instead of part CaO, makes it compared with prior art, and have the following advantages and positively effect: slag system possesses low hydrogen penetrating quality; The hydrogen rate of permeation is reduced to 0.98 * 10-6molcm-1min-1 by existing up to 2.35 * 10-6molcm-1min-1, effectively reduce the hydrogen richness in the remelting initial stage steel, make that hydrogen richness keeps a lower level, hydrogen richness＜1.5ppm in the steel after the remelting in the steel of normal remelting phase.

Embodiment

Embodiment 1: the experiment slag system sees Table 1

Table 1 slag system component

Adopt the ESR ingot of above-mentioned slag system remelting MC5 cold roll with steel, the used consumable electrode of remelting adopts the 100kg vacuum induction melting, and the electrode that forges into diameter 70mm carries out esr.The slag system raw material is selected industrial materials for use, and slag charge is through after the melting, is broken into that granular (3～8mm), through 850 ℃ of insulations baking in 4 hours, the bits add-on be a ton steel 30Kg before using, and reflow process employing argon gas protects that (argon pressure is 0.15MPa, and flow is 5m ³/ h), measure the hydrogen richness in each stage.The results are shown in Table 2

Each stage hydrogen richness of table 2 reflow process

Embodiment 2: the experiment slag system sees Table 3

Table 3 slag system component

Adopt the ESR ingot of above-mentioned slag system remelting MC5 cold roll with steel, the used consumable electrode of remelting adopts the 100kg vacuum induction melting, and the electrode that forges into diameter 70mm carries out esr.The slag system raw material is selected industrial materials for use, and slag charge is through after the melting, is broken into that granular (5～10mm), through 800 ℃ of insulations baking in 4 hours, the bits add-on be a ton steel 35Kg before using, and reflow process employing argon gas protects that (argon pressure is 0.18MPa, and flow is 5m ³/ h.), measure the hydrogen richness in each stage.The results are shown in Table 4

Each stage hydrogen richness of table 4 reflow process

Embodiment 3: the experiment slag system sees Table 5

Table 5 slag system component

Adopt the ESR ingot of above-mentioned slag system remelting MC5 cold roll with steel, the used consumable electrode of remelting adopts the 100kg vacuum induction melting, and the electrode that forges into diameter 70mm carries out esr.The slag system raw material is selected industrial materials for use, and slag charge is through after the melting, is broken into that granular (4～9mm), through 850 ℃ of insulations baking in 8 hours, the bits add-on be a ton steel 30Kg before using, and reflow process employing argon gas protects that (argon pressure is 0.25MPa, and flow is 6m ³/ h.), measure the hydrogen richness in each stage.The results are shown in Table 6

Each stage hydrogen richness of table 6 reflow process

Embodiment 4: the experiment slag system sees Table 7

Table 7 slag system component

Adopt the ESR ingot of above-mentioned slag system remelting MC5 cold roll with steel, the used consumable electrode of remelting adopts the 100kg vacuum induction melting, and the electrode that forges into diameter 70mm carries out esr.The slag system raw material is selected industrial materials for use, and slag charge is through after the melting, is broken into that granular (4～10mm), through 850 ℃ of insulations baking in 6 hours, the bits add-on be a ton steel 40Kg before using, and reflow process employing argon gas protects that (argon pressure is 0.20MPa, and flow is 5m ³/ h.), measure the hydrogen richness in each stage.The results are shown in Table 8

Each stage hydrogen richness of table 8 reflow process

Embodiment 5: the experiment slag system sees Table 9

Table 9 slag system component

Adopt the ESR ingot of above-mentioned slag system remelting MC5 cold roll with steel, the used consumable electrode of remelting adopts the 100kg vacuum induction melting, and the electrode that forges into diameter 70mm carries out esr.The slag system raw material is selected industrial materials for use, and slag charge is through after the melting, is broken into that granular (3～10mm), through 900 ℃ of insulations baking in 4 hours, the bits add-on be a ton steel 35Kg before using, and reflow process employing argon gas protects that (argon pressure is 0.22MPa, and flow is 6m ³/ h.), measure the hydrogen richness in each stage.The results are shown in Table 10

Each stage hydrogen richness of table 10 reflow process

The CaF that the foregoing description explanation adopts MgO instead of part CaO to form ₂-CaO-Al ₂O ₃-SiO ₂The many first slag systems of-MgO, and adopt pre-melted slag and argon shield to carry out esr the hydrogen richness of cold roll blank esr can be controlled at below the 1.5ppm, to have played preventing that the esr whole process from increasing the effect of hydrogen, effect is remarkable.

Claims (4)

1. electroslag remelting slag system with low hydrogen permeability, the weight percent proportioning of its chemical ingredients is CaF ₂: 45～50%, CaO:10～15%, Al ₂O ₃: 30～35%, SiO ₂: 5～10%, MgO:5～10%.

2. the preparation method of an electroslag remelting slag system with low hydrogen permeability is characterized in that may further comprise the steps:

1) by following weight percent proportioning preparation: CaF ₂: 45～50%, CaO:10～15%, Al ₂O ₃: 30～35%, SiO ₂: 5～10%, MgO:5～10%;

2) pre-melted slag that is equipped with the electric smelting legal system, slag electric current: 2000～4000A; Voltage: 46～48V; Tap to tap time: 45～55 minutes: mould cool time: 30～60 minutes;

3) be broken into after the melting granular.

3. the preparation method of a kind of electroslag remelting slag system with low hydrogen permeability as claimed in claim 2 is characterized in that broken granular size is 3～10mm in the described step 3).

4. the using method of an electroslag remelting slag system with low hydrogen permeability is characterized in that may further comprise the steps:

1) weight percent of slag system composition is: CaF ₂: 45～50%, CaO:10～15%, Al ₂O ₃: 30～35%, SiO ₂: 5～10%, MgO:5～10%;

2) toasted in 4～8 hours through 800～900 ℃ of insulations before the use, to remove the moisture content in the slag;

3) ratio with ton steel 30～40kg adds baked bits in electroslag furnace;

4) top of crystallizer for electroslag furnace adopts argon gas to protect, and argon pressure is 0.15～0.25MPa, and flow is 5～6m ³/ h.