CN117444470B - Low-volatility high-heat-transfer smelting flux and preparation method and application thereof - Google Patents
Low-volatility high-heat-transfer smelting flux and preparation method and application thereof Download PDFInfo
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- CN117444470B CN117444470B CN202311802824.6A CN202311802824A CN117444470B CN 117444470 B CN117444470 B CN 117444470B CN 202311802824 A CN202311802824 A CN 202311802824A CN 117444470 B CN117444470 B CN 117444470B
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- 230000004907 flux Effects 0.000 title claims abstract description 196
- 238000003723 Smelting Methods 0.000 title claims abstract description 130
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- 238000002360 preparation method Methods 0.000 title abstract description 15
- 238000007716 flux method Methods 0.000 title description 2
- 238000003466 welding Methods 0.000 claims abstract description 257
- 229910004261 CaF 2 Inorganic materials 0.000 claims abstract description 40
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 28
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- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims abstract description 26
- 229910052796 boron Inorganic materials 0.000 claims abstract description 15
- 238000000034 method Methods 0.000 claims description 38
- 239000000463 material Substances 0.000 claims description 21
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 15
- 229910001566 austenite Inorganic materials 0.000 claims description 11
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- 238000002844 melting Methods 0.000 description 10
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- 239000011737 fluorine Substances 0.000 description 8
- 229910052731 fluorine Inorganic materials 0.000 description 8
- 230000002829 reductive effect Effects 0.000 description 8
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 7
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- 239000007789 gas Substances 0.000 description 7
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- 230000015572 biosynthetic process Effects 0.000 description 6
- 230000007547 defect Effects 0.000 description 6
- 229910052760 oxygen Inorganic materials 0.000 description 6
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 5
- 229910004298 SiO 2 Inorganic materials 0.000 description 5
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- 210000003625 skull Anatomy 0.000 description 5
- 229910045601 alloy Inorganic materials 0.000 description 4
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- 229910000859 α-Fe Inorganic materials 0.000 description 3
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
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- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 2
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- 229910016569 AlF 3 Inorganic materials 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 1
- SXSVTGQIXJXKJR-UHFFFAOYSA-N [Mg].[Ti] Chemical compound [Mg].[Ti] SXSVTGQIXJXKJR-UHFFFAOYSA-N 0.000 description 1
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/22—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting characterised by the composition or nature of the material
- B23K35/36—Selection of non-metallic compositions, e.g. coatings, fluxes; Selection of soldering or welding materials, conjoint with selection of non-metallic compositions, both selections being of interest
- B23K35/362—Selection of compositions of fluxes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
- B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
- B23K35/00—Rods, electrodes, materials, or media, for use in soldering, welding, or cutting
- B23K35/40—Making wire or rods for soldering or welding
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
Abstract
The invention relates to the technical field of welding, in particular to a low-volatility high-heat transfer smelting flux, and a preparation method and application thereof. The low-volatility high-heat transfer smelting flux is prepared from the following components in percentage by mass: siO (SiO) 2 31%~35%，MgO 9.5%~11%，Al 2 O 3 24%~27%，CaF 2 16%~19%，Fe 2 O 3 9.5% -11% and B 2 O 3 5% -8%. The low-volatility high-heat transfer smelting flux has stable components after welding, excellent deslagging performance and excellent weld surface quality and mechanical property. The low-volatility high-heat transfer smelting flux is matched with the ship plate steel weld joint to form attractive appearance, the surface is free from flux adhesion, and the microstructure grain size is reasonable.
Description
Technical Field
The invention relates to the technical field of welding, in particular to a low-volatility high-heat transfer smelting flux, and a preparation method and application thereof.
Background
The large-line energy submerged arc welding has the characteristics of high deposition efficiency, good weld metal formability and strong welding stability, and is widely applied to various large-scale manufacturing fields. The welding flux is one of main consumables of submerged arc welding, and can isolate air, treat alloy, improve welding manufacturability and the like in the welding process, so that various necessary physical and chemical properties of weld metal are ensured, and the smelting type welding flux is not easy to absorb moisture and has high recycling rate. Therefore, the development of a flux capable of maintaining and improving the quality of weld metal is one of the main development directions of thick plate welding at present.
In the prior art, the common practice is toWith CaF 2 So as to reduce the oxygen potential and hydrogen content of the welding flux, effectively reduce the melting point, high-temperature viscosity and surface tension of slag, and increase the fluidity of slag, thereby improving the formability of weld metal.
At the same time by SiO 2 The welding flux with the components as the main body has good arc stability in the welding process, and can transfer more silicon elements into weld metal to maintain the mechanical property of the weld metal; on the other hand, the silicon-rich flux has strong amorphous forming capability and uniform element distribution after welding.
However, existing high-energy, high-silicon smelting fluxes contain more CaF 2 The fluorine volatilizes obviously in the process of smelting the flux and welding, so that the actual components and the design components generate larger deviation, the physical and chemical properties of the flux are also obviously changed, the welding performance of the flux is seriously affected, the recovery difficulty of the flux is high, and the recovery cost is high. On the other hand, the high-viscosity welding flux is extremely easy to adhere to the surface of a welding seam and poor in deslagging performance, and bubbles rising from a molten pool stay between the welding flux and welding seam metal to cause defects of the surface of the welding seam such as a press pit. Furthermore, high SiO 2 The flux is easy to form a large number of amorphous structures at the position close to the slag-metal interface, so that heat transfer is greatly hindered, and the coarsening of a weld metal structure is caused, so that the mechanical property of the welded joint is deteriorated, and the requirement of a service environment on the weld property is difficult to meet.
In view of this, the present invention has been made.
Disclosure of Invention
The first object of the present invention is to provide a low-volatility high-heat transfer flux which ensures stable post-weld composition due to low activity, high heat transfer and high internal bonding force, and post-smelting CaF 2 The component change is small, the deslagging performance is excellent, the weld joint surface quality and mechanical property are excellent, and the weld joint components and tissues are uniform. The low-volatility high-heat transfer smelting flux is matched with the ship plate steel weld joint to form attractive appearance, the surface is free from flux adhesion, the microstructure grain size is reasonable, and the mechanical property is excellent.
The second aim of the invention is to provide a preparation method of the low-volatility high-heat transfer smelting flux.
The third object of the invention is to provide an application of the low-volatility high-heat transfer smelting flux in the steel for the large heat input welding ocean engineering.
In order to achieve the above object of the present invention, the following technical solutions are specifically adopted:
the invention firstly provides a low-volatility high-heat transfer smelting flux which is prepared from the following components in percentage by mass: siO (SiO) 2 31%~35%，MgO 9.5%~11%，Al 2 O 3 24%~27%，CaF 2 16%~19%，Fe 2 O 3 9.5% -11% and B 2 O 3 5%~8%。
Preferably, the granularity of the low-volatility high-heat transfer smelting flux is 8-35 meshes.
Preferably, caF in the raw material for preparing the low-volatility high-heat transfer smelting flux 2 Mass fraction to CaF in the low-volatility high-heat transfer smelting flux 2 The absolute value of the difference between the mass fractions of (a) is less than or equal to 0.7%.
The slag removal rate of a welding seam formed after welding by using the low-volatility high-heat transfer smelting flux is more than or equal to 90 percent.
The average length of austenite grains in a weld joint formed after welding by using the low-volatility high-heat transfer smelting flux is less than or equal to 90 mu m.
Preferably, the longitudinal impact toughness of the welding seam formed by welding the low-volatility high-heat transfer smelting flux at the temperature of minus 40 ℃ is more than or equal to 70J.
The tensile strength of a welding seam formed after welding by using the low-volatility high-heat transfer smelting flux is more than or equal to 665Mpa.
The elongation of the welding seam formed after welding by using the low-volatility high-heat transfer smelting flux is more than or equal to 36%.
The invention further provides a preparation method of the low-volatility high-heat transfer smelting flux, which comprises the following steps:
SiO is made of 2 、MgO、Al 2 O 3 、CaF 2 、Fe 2 O 3 And B 2 O 3 Mixing and smelting to obtain a molten liquid; wherein the smelting temperature<1500℃；
Carrying out water quenching on the melt to obtain a quenched material;
roasting the quenched material, and cooling to obtain the low-volatility high-heat transfer smelting flux.
Preferably, the smelting temperature is 1400-1450 ℃, and the heat preservation time of smelting is 0.5-2 h.
Preferably, the roasting temperature is 650-800 ℃, and the heat preservation time of the roasting is 1.5-3 hours.
Preferably, after said firing, the steps of crushing and sieving are also included.
The invention also provides application of the low-volatility high-heat transfer smelting flux in high-heat transfer welding of steel for ocean engineering, wherein the high-heat transfer smelting flux is welded by tandem double-wire submerged arc welding; the front wire of the series double-wire submerged arc welding adopts direct current, the welding current of the direct current is 800A-870A, and the welding voltage of the direct current is 30V-36V; the back wire of the series double-wire submerged arc welding adopts alternating current, the welding current of the alternating current is 625A-800A, and the welding voltage of the alternating current is 28V-44V.
Preferably, the line energy of the large line energy welding is 55 kJ/cm-85 kJ/cm.
The welding speed of the large heat input welding is 45 cm/min-60 cm/min.
The stacking height of the low-volatility high-heat transfer smelting flux is 21 mm-37 mm.
The welding wire spacing of the series double-wire submerged arc welding is 24-28 mm.
And the elongation of the welding wire of the tandem double-wire submerged arc welding is 24-26 mm.
Compared with the prior art, the invention has the beneficial effects that:
(1) The low-volatility high-heat-transfer smelting flux provided by the invention has the advantages of excellent slag removal performance after welding, attractive weld joint formation, good arc stability in the welding process, no pore and crack defect of the weld joint, excellent mechanical property of the weld joint, uniform weld joint composition and structure, attractive weld joint formation, no adhesion of the flux on the surface and reasonable microstructure grain size when being matched with ship plate steel weld joint formation.
(2) The low-volatility high-heat transfer smelting flux provided by the invention has CaF after smelting 2 The composition change is small, the average grain size of austenite grains of the welding seam is low, the longitudinal impact toughness at the low temperature of minus 40 ℃ is good, the tensile strength is high, and the elongation is high.
(3) The low-volatility high-heat-transfer smelting flux provided by the invention has good fluorine fixing effect, low fluorine volatilization rate and environmental friendliness by adopting proper component proportion.
(4) The low-volatility high-heat-transfer smelting flux provided by the invention has stable components, high recovery rate of the flux which can be directly recovered, and the residual flux after welding can be continuously used for the next welding.
(5) The low-volatility high-heat transfer smelting flux provided by the invention has the advantages that the grain size of a welded seam tissue obtained after welding is small, and the low-temperature impact toughness of the welded seam is excellent.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are needed in the description of the embodiments or the prior art will be briefly described, and it is obvious that the drawings in the description below are some embodiments of the present invention, and other drawings can be obtained according to the drawings without inventive effort for a person skilled in the art.
FIG. 1 is a graph of the macro topography of the cross section of a welded joint obtained after the welding of example 4 provided by the invention;
FIG. 2 is a graph showing the morphology of the weld bead obtained after the welding of example 4 provided by the invention;
FIG. 3 is a microstructure view of a welded joint obtained after welding in example 4 provided by the present invention;
FIG. 4 is a topography of the skull removed after welding according to example 7 provided by the present invention;
FIG. 5 is an EDS diagram of a skull that is removed after welding according to comparative example 2 provided by the present invention;
FIG. 6 is a microstructure view of a welded joint obtained after welding in comparative example 2 provided by the present invention;
FIG. 7 is a graph showing the morphology of the weld bead obtained after the welding of comparative example 3 provided by the present invention;
FIG. 8 is a graph of the macro topography of the weld cross-section obtained after the welding of comparative example 4 provided by the present invention.
Detailed Description
The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and detailed description, but it will be understood by those skilled in the art that the examples described below are some, but not all, examples of the present invention, and are intended to be illustrative of the present invention only and should not be construed as limiting the scope of the present invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
In the present invention, unless specifically stated otherwise, the terms "first", "second", "third", "fourth", etc. are used for descriptive purposes only and are not to be construed as indicating or implying a relative importance or quantity or as implicitly indicating the importance or quantity of the indicated technical feature. Moreover, the terms "first," "second," "third," "fourth," and the like are used for non-exhaustive list description purposes only, and are not to be construed as limiting the number of closed forms.
The terms "comprising" and "including" as used herein mean open ended or closed ended, unless otherwise noted. For example, the terms "comprising" and "comprises" may mean that other components not listed may be included or included, or that only listed components may be included or included.
In the present invention, "one or more" or "at least one" means any one, any two or more of the listed items unless specifically stated otherwise. Wherein "several" means any two or more.
In a first aspect, the invention provides a low-volatility high-heat transfer smelting flux, which is low in volatility and high in heat transferThe heat transfer smelting flux is prepared from the following components in percentage by mass: siO (SiO) 2 31%~35%，MgO 9.5%~11%，Al 2 O 3 24%~27%，CaF 2 16%~19%，Fe 2 O 3 9.5% -11% and B 2 O 3 5%~8%。
The low-volatilization high-heat transfer smelting flux is suitable for welding large-line energy thick plates.
Wherein SiO is 2 Including, but not limited to, any one of the point values of 31%, 32%, 33%, 34%, 35% or a range between any two by mass percent.
MgO includes, but is not limited to, a point value of any one of 9.5%, 10%, 10.5%, 11% or a range value between any two in mass percent.
Al 2 O 3 Including, but not limited to, any one of 24%, 25%, 26%, 27% by mass, or any range between any two.
CaF 2 Including, but not limited to, any one of 16%, 17%, 18%, 19% by mass, or any range between any two.
Fe 2 O 3 Including, but not limited to, any one of the point values of 9.5%, 10%, 10.5%, 11% or a range between any two by mass percent.
B 2 O 3 Including, but not limited to, any one of the point values of 5%, 6%, 7%, 8% or a range between any two by mass percent.
The invention suppresses volatilization of fluorine at high temperature by regulating and controlling the component activity and structure of the low-volatility high-heat-transfer smelting flux, and improves the surface quality of weld metal and the physical property of a welded joint by utilizing the characteristics of low viscosity and fast heat transfer of the low-fluorine volatilization flux. From the perspective of fluorine volatilization control, fluorine is in CaF 2 、SiF 4 The volatilization of gases and other forms can reduce the volatilization of fluorine to the maximum extent by regulating and controlling the low activity and kinetic viscosity of the reactant in the thermodynamics, thus realizing the stable production and easy recovery of the flux. From the heat transfer perspective, the coarse crystalline phase formed at the bottom of the flux skull during cooling has strong internal binding force and is easier to be connected with weld metalAnd the separation and slag removal of the welding flux are good. Secondly, the viscosity of the bottom crystallized flux is smaller, and air bubbles floating in a welding pool can smoothly escape from the flux, so that the defect of pit formation caused by capturing at a slag-gold interface is avoided. Finally, the higher thermal conductivity of the low-volatility welding flux accelerates the heat dissipation in the welding flux, accelerates the solidification process of a welding pool, inhibits the growth of weld metal, and finally achieves the effect of fine grain strengthening.
The low-volatility high-heat-transfer smelting flux can ensure that the welded joint obtained after welding has higher mechanical property and meets the use requirement of a severe service environment.
The flux composition is one of the decisive factors affecting the welding quality of submerged arc welding. The excellent welding flux needs proper melting point and viscosity, and can play a good role in mechanical protection, metallurgical treatment and the like of welding seams. The invention adopts the SiO with specific dosage 2 、MgO、Al 2 O 3 、CaF 2 、Fe 2 O 3 And B 2 O 3 Excellent deslagging performance can be obtained, and proper viscosity and fluidity of slag can be ensured. The obtained weld joint has good formability, no surface defect, fine structure crystal grains and excellent low-temperature impact toughness. In particular, the invention adopts SiO 2 The alloy is used for transiting Si element to weld metal, so that the burning loss of alloy element in the welding process can be effectively supplemented, and the weld metal component is ensured to be in a standard range. MgO in the flux can reduce CaF 2 Is effective in inhibiting CaF 2 Volatilizing the isogas phase; transition Mg into the weld joint, formation of magnesium-titanium-containing composite inclusion in the weld joint induces acicular ferrite nucleation, and combination of Fe 2 O 3 Oxygen is transited into the weld joint, and the weld joint metal is strengthened by means of oxide metallurgy. In addition, boron can also pass through the welding flux to be transited into the welding seam, and plays a role in refining welding seam grains.
More specifically, in the low-volatility high heat transfer smelting flux composition of the present invention: siO (SiO) 2 Is an acidic substance, and has the functions of slagging, adjusting the viscosity and fluidity of the welding flux, improving the formability and the like. SiO (SiO) 2 The high-temperature melting body serves as a network framework in the high-temperature melting body structure, so that the high-temperature viscosity and the surface tension of the slag can be obviously improved. In addition，SiO 2 The Si element can be transited into a weld pool, and the tensile strength and the hardness of the weld can be improved by a proper amount of Si. In the present invention, siO 2 The addition amount of (C) is in a proper range. SiO (SiO) 2 When the addition amount is too high, the high-temperature viscosity of the welding flux is high, and gas is prevented from escaping in the welding process, so that more air hole defects are generated. In addition, the weld joint is seriously increased in Si and O, and the mechanical property of weld joint metal is reduced; and SiO 2 When the content is too low, arc stability is poor, and arc breakage is liable to occur.
Al 2 O 3 The melting point can be regulated and controlled, and the fluidity of slag is improved. Al in flux 2 O 3 Too high content can increase the viscosity of slag, reduce the fluidity of slag liquid and easily adhere slag on the surface of a welding line. Too little Al 2 O 3 The flux viscosity is too low and the ability to cover the melt pool is reduced.
B 2 O 3 Is an amphoteric oxide, and mainly plays a role in regulating the melting point and the thermal expansion coefficient of the welding flux. Can be combined with other components in the flux to form a low-melting-point compound, thereby greatly reducing the high-temperature viscosity and the thermal expansion coefficient of the flux and improving the slag fluidity and the weld joint formability. The material has good stability. B (B) 2 O 3 Is added in proper amount, not only avoids B 2 O 3 The problems of too high slag viscosity, too high slag solidification temperature, poor slag removal and poor weld joint spreadability caused by too high addition amount can be solved, and the problems of too low slag viscosity, poor cladding effect, easy transition of B element excess and reduced weld joint toughness caused by too low addition amount can be avoided.
MgO is an alkaline substance, can adjust the composition range of the welding flux in the high-temperature liquid phase region, and improves the impact toughness of weld metal to a certain extent. In addition, the addition of MgO can reduce CaF 2 Activity and thus reduce CaF 2 Is volatilized. In the present invention, the amount of MgO to be added is in a suitable range. Too much MgO increases the solidification temperature of the slag, thereby severely affecting weld formability. Too little MgO increases CaF on the one hand 2 To accelerate CaF 2 On the other hand, the volatilization of the magnesium-containing inclusion is too little, the induced acicular ferrite nucleation is little, and the strengthening effect is not obvious.
CaF 2 The oxygen potential of the flux can be reduced and the oxygen content of the weld metal can be reduced. Secondly, the melting point, high-temperature viscosity and surface tension of the slag can be effectively reduced, and the fluidity of the slag is increased, so that the formability of weld metal is improved. CaF provided by the invention 2 Is suitable for use in too small an amount of CaF 2 The alkalinity of the welding flux is smaller, the melting point of the welding flux is higher, and the impact toughness of the welding seam is lower; and too large an amount may result in poor welding process performance.
Fe 2 O 3 Can supply a certain amount of oxygen to the weld so that enough inclusions can be generated to induce acicular ferrite nucleation. On the other hand, fe is added 2 O 3 Helping to reduce weld porosity and stabilize the arc. In addition, fe element in the welding line can be effectively restrained from entering the slag shell, and fluctuation of welding flux and welding line components is prevented.
In some specific embodiments, the low-volatility high heat transfer flux has a particle size of 8 mesh to 35 mesh, including but not limited to a spot value of any one of 8 mesh, 10 mesh, 15 mesh, 20 mesh, 25 mesh, 30 mesh, 35 mesh, or a range value between any two.
By adopting the low-volatility high-heat transfer smelting flux with the granularity, the reaction area between the welding seam and the flux is increased, and meanwhile, the blocking of floating gas is avoided, so that good reactivity and welding seam formability are ensured.
The low-volatility high-heat transfer smelting flux provided by the invention has small component change after smelting, and CaF 2 Is stable in composition. In some embodiments, caF in the raw material for preparing the low-volatility high-heat transfer smelting flux 2 Mass fraction to CaF in the low-volatility high-heat transfer smelting flux 2 The absolute value of the difference of mass fractions is less than or equal to 0.7%; including but not limited to any one of the point values or range values between any two of 0.7%, 0.68%, 0.67%, 0.65%, 0.62%, 0.6%, 0.58%, 0.55%, 0.53%, 0.5%, 0.4%, 0.3%, 0.2%, 0.1%, 0.05%, 0.03%, 0.01%.
The low-volatility high-heat transfer smelting flux provided by the invention has good deslagging performance. In some specific embodiments, the deslagging rate of a welding seam formed after welding by using the low-volatility high-heat transfer smelting flux is more than or equal to 90%; including but not limited to any one of the point values or range values between any two of 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%.
The microstructure grain size of the welded seam obtained after the low-volatility high-heat transfer smelting flux is welded is small, and the toughness of welded seam metal can be improved. In some specific embodiments, the average length of austenite grains in a weld joint formed after welding using the low-volatility high heat transfer flux is less than or equal to 90 μm, including, but not limited to, a point value of any one of 90 μm, 88 μm, 87 μm, 86 μm, 85 μm, 84 μm, 83 μm, 82 μm, 81 μm, 80 μm, 78 μm, 75 μm, or a range value between any two.
The low-temperature impact toughness of the low-volatility high-heat transfer smelting flux provided by the invention is excellent. In some specific embodiments, the longitudinal impact toughness of a weld joint formed after welding by using the low-volatility high-heat transfer smelting flux at the temperature of minus 40 ℃ is more than or equal to 70J; including but not limited to a point value of any one of 70J, 71J, 72J, 73J, 75J, 76J, 78J, 80J, 82J, 83J, 84J, 85J, 86J, 88J, 90J or a range value therebetween.
The low-volatility high-heat transfer smelting flux provided by the invention has high tensile strength. In some specific embodiments, the tensile strength of a weld joint formed after welding by using the low-volatility high-heat transfer smelting flux is more than or equal to 665Mpa; including but not limited to any one of or a range of values between 665Mpa, 666Mpa, 670Mpa, 672Mpa, 675Mpa, 678Mpa, 680Mpa, 683Mpa, 685Mpa, 687Mpa, 690Mpa, 695Mpa, 700 Mpa.
The low-volatility high-heat transfer smelting flux provided by the invention has high elongation. In some embodiments, the elongation of the weld formed after welding using the low-volatility high-heat transfer flux is greater than or equal to 36%, including, but not limited to, any one of 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 45%, or a range of values therebetween.
In a second aspect, the invention provides a preparation method of the low-volatility high-heat transfer smelting flux, which comprises the following steps:
SiO is made of 2 、MgO、Al 2 O 3 、CaF 2 、Fe 2 O 3 And B 2 O 3 Uniformly mixing, smelting to obtain molten liquid in a molten state, and uniformly dispersing the components.
Wherein the smelting temperature is <1500 ℃, including but not limited to, any one of or a range of values of 1380 ℃, 1400 ℃, 1410 ℃, 1420 ℃, 1430 ℃, 1440 ℃, 1450 ℃, 1460 ℃, 1480 ℃.
And carrying out water quenching on the melt to obtain a quenched material.
Roasting the quenched material, and cooling to obtain the low-volatility high-heat transfer smelting flux.
Wherein, the purpose of calcination is: and removing residual crucible carbon powder and water in the quenched material.
The preparation method has the advantages of simple operation, short flow, suitability for mass production, excellent mechanical properties of the prepared low-volatility high-heat-transfer smelting flux and the like.
And, the invention controls the smelting temperature<1500 ℃ can avoid CaF 2 And the gas escapes.
In some specific embodiments, the smelting temperature is 1400 ℃ to 1450 ℃, including, but not limited to, any one or range of values between 1400 ℃, 1410 ℃, 1420 ℃, 1430 ℃, 1440 ℃, 1450 ℃.
In some specific embodiments, the heat preservation time of the smelting is 0.5 h-2 h, including but not limited to a point value of any one of 0.5h, 1h, 1.5h, 2h or a range value between any two.
In some specific embodiments, the firing temperature is 650 ℃ to 800 ℃, including but not limited to any one of, or a range of values between, 650 ℃, 670 ℃, 700 ℃, 730 ℃, 750 ℃, 780 ℃, 800 ℃.
And roasting can remove residual crucible carbon powder impurities in the quenched materials.
In some specific embodiments, the baking time is 1.5 h-3 h, including but not limited to any one of the point values or any range between the two values of 1.5h, 2h, 2.5h, 3 h.
In some embodiments, after the firing, the steps of crushing and sieving are further included.
In some embodiments, the particle size of the low-volatility high heat transfer flux after the crushing and the sieving is 8 mesh to 38 mesh, including but not limited to a point value of any one of 8 mesh, 18 mesh, 28 mesh, 38 mesh, or a range value between any two.
In some embodiments, siO 2 、MgO、Al 2 O 3 、CaF 2 、Fe 2 O 3 And B 2 O 3 SiO is added before mixing 2 、MgO、Al 2 O 3 、CaF 2 、Fe 2 O 3 And B 2 O 3 Drying to remove water from each raw material to obtain a dried raw material.
In some embodiments, drying may be performed using any drying apparatus commonly used in the art and conventional drying methods. For example, the materials are placed in a forced air drying oven and dried for 2 to 3.5 hours at the temperature of 200 to 250 ℃.
In some specific embodiments, siO is weighed according to the proportion of the low-volatility high-heat transfer smelting flux 2 、MgO、Al 2 O 3 、CaF 2 、Fe 2 O 3 And B 2 O 3 。
In some specific embodiments, in order to prevent the molten liquid from being oxidized, argon is continuously introduced into the system in the smelting process, and the flow rate of the argon can be, for example, 0.3L/min to 0.5L/min.
In some specific embodiments, before roasting, placing the quenched material into a blast drying oven at 200-250 ℃ for 2-3 hours to completely remove water.
In some embodiments, the firing may employ any sintering equipment commonly used in the art, such as, but not limited to, a muffle furnace.
In a third aspect, the invention provides application of the low-volatility high-heat transfer smelting flux in high heat input welding of marine engineering steel, wherein the high heat input welding is serial double-wire submerged arc welding.
The front wire of the series double-wire submerged arc welding adopts direct current, and the welding current of the direct current is 800A-870A, including but not limited to any one point value or range value between any two points of 800A, 810A, 820A, 830A, 840A, 850A, 860A and 870A.
The welding voltage of the direct current is 30V-36V, including but not limited to any one of 30V, 31V, 32V, 33V, 34V, 35V and 36V or a range value between any two points.
The back wire of the series double-wire submerged arc welding adopts alternating current, and the welding current of the alternating current is 625A-800A, including but not limited to any one point value or range value between any two points of 625A, 650A, 675A, 700A, 725A, 750A, 775A and 800A.
The welding voltage of the alternating current is 28V-44V, including but not limited to any one point value or any range value between any two points of 28V, 29V, 30V, 31V, 32V, 33V, 34V, 35V, 36V, 37V, 38V, 39V, 40V, 41V, 42V, 43V and 44V.
In some specific embodiments, the line energy of the high line energy welding is 55kJ/cm to 85kJ/cm; including but not limited to a point value of any one of 55kJ/cm, 60kJ/cm, 65kJ/cm, 70kJ/cm, 75kJ/cm, 80kJ/cm, 85kJ/cm, or a range value between any two.
In some specific embodiments, the welding speed of the high heat input welding is 45cm/min to 60cm/min; including but not limited to a point value of any one of 45cm/min, 48cm/min, 50cm/min, 53cm/min, 55cm/min, 58cm/min, 60cm/min, or a range value between any two points.
In some specific embodiments, the low-volatility high heat transfer flux has a bulk height of 21mm to 37mm, including but not limited to a point value of any one of 21mm, 22mm, 23mm, 24mm, 25mm, 26mm, 27mm, 28mm, 29mm, 30mm, 31mm, 32mm, 33mm, 34mm, 35mm, 36mm, 37mm, or a range value between any two points.
In some specific embodiments, the welding wire spacing of the tandem double wire submerged arc welding is 24 mm-28 mm, including but not limited to any one of 24mm, 25mm, 26mm, 27mm, 28mm, or a range of values between any two points.
In some specific embodiments, the welding wire elongation of the tandem double-wire submerged arc welding is 24 mm-26 mm, including but not limited to any one of 24mm, 25mm, 26mm, or a range of values between any two points.
In some specific embodiments, the marine engineering steel includes any kind of marine engineering steel, for example, but not limited to, steel for hull structure EH690, steel for hull structure EH550, steel for hull structure EH420, steel for hull structure EH36, and the like.
In some specific embodiments, the marine engineering steel has a thickness of 23mm to 32mm, including but not limited to a point value of any one of 23mm, 24mm, 25mm, 26mm, 27mm, 28mm, 29mm, 30mm, 31mm, 32mm, or a range of values between any two points.
Embodiments of the present invention will be described in detail below with reference to examples, but it will be understood by those skilled in the art that the following examples are only for illustrating the present invention and should not be construed as limiting the scope of the present invention. The specific conditions are not noted in the examples and are carried out according to conventional conditions or conditions recommended by the manufacturer. The reagents or apparatus used were conventional products commercially available without the manufacturer's attention.
Example 1
The low-volatility high-heat transfer smelting flux provided by the embodiment is prepared from the following components in percentage by mass: siO (SiO) 2 35%，MgO 9.5%，Al 2 O 3 24%，CaF 2 17%，Fe 2 O 3 9.5% and B 2 O 3 5%。
The preparation method of the low-volatility high-heat transfer smelting flux provided by the embodiment comprises the following steps:
(1) SiO is made of 2 、MgO、Al 2 O 3 、CaF 2 、Fe 2 O 3 And B 2 O 3 Drying in a drying oven at 200deg.C for 3 hr to remove water in the materials to obtain each dry material. According to the proportion, weighing and mixing all dry raw materials with the total amount of 1.5kg, uniformly stirring, and then placing into a graphite crucible.
(2) And (3) placing the graphite crucible containing the raw materials obtained in the step (1) in a high-temperature constant-temperature region of a high-temperature resistance furnace, smelting at the temperature of 1420 ℃, and preserving the temperature for 0.5h to obtain a melt. To prevent the melt from being oxidized, argon gas was continuously introduced at a flow rate of 0.3L/min. And then rapidly carrying out water quenching granulation on the liquid melt to obtain a water quenching material. And (3) placing the collected water quenched material in a blast drying oven at 250 ℃ and drying for 2 hours to completely remove water to obtain a dry water quenched material.
(3) And (3) placing the dried water quenched material obtained in the step (2) in a muffle furnace, and roasting for 3 hours at 650 ℃ to remove residual crucible carbon powder and water in the material, thereby obtaining the semi-finished product welding flux.
(4) Crushing and screening the semi-finished flux obtained in the step (3) to enable the granularity of flux particles to be 8-35 meshes, wherein fine particles above 30 meshes are not more than 10%, and coarse particles below 10 meshes are not more than 10%, so that the low-volatility high-heat-transfer smelting flux is obtained.
The low-volatility high-heat transfer smelting flux prepared by the embodiment is used for large heat input welding, and the welding method comprises the following steps: the low-volatility high-heat transfer smelting flux prepared in the embodiment is dried for 2 hours at the temperature of 250 ℃, and the dried flux is matched with a CHW-S3 welding wire (H10 Mn2 type) to weld the 30mm thick sea work steel EH 36-grade ship plate steel by adopting a tandem double-wire submerged arc welding method. In the welding process, the welding line energy is 61kJ/cm, the stacking height of welding flux is 26mm, the welding speed is 55cm/min, the welding wire distance is 25mm, the welding wire elongation is 25mm, the front wire of the series double-wire submerged arc welding adopts direct current, the welding current/welding voltage of the direct current is 800A/30V, the rear wire of the series double-wire submerged arc welding adopts alternating current, and the welding current/welding voltage of the alternating current is 725A/44V.
Example 2
The low-volatility high-heat transfer smelting flux provided by the embodiment comprises the following components in percentage by massThe proportion meter is prepared from the following components: siO (SiO) 2 34%，MgO 9.5%，Al 2 O 3 25%，CaF 2 16%，Fe 2 O 3 9.5% and B 2 O 3 6%。
The preparation method of the low-volatility high-heat transfer smelting flux provided in the embodiment is basically the same as that in the embodiment 1, except that: in the step (1), the drying temperature is 220 ℃, and the drying time is 2.5 hours; in the step (2), the smelting temperature is 1430 ℃, and the heat preservation time of smelting is 1h; in the step (3), the roasting temperature is 700 ℃ and the roasting time is 2 hours.
The low-volatility high-heat transfer smelting flux prepared by the embodiment is used for welding, and the welding method and parameters are the same as those of the embodiment 1.
Example 3
The low-volatility high-heat transfer smelting flux provided by the embodiment is prepared from the following components in percentage by mass: siO (SiO) 2 32%，MgO 10%，Al 2 O 3 26%，CaF 2 16%，Fe 2 O 3 10% and B 2 O 3 6%。
The preparation method of the low-volatility high-heat transfer smelting flux provided in the embodiment is basically the same as that in the embodiment 1, except that: in the step (1), the drying temperature is 240 ℃ and the drying time is 2 hours; in the step (2), the smelting temperature is 1440 ℃, and the smelting heat preservation time is 2 hours; in the step (3), the roasting temperature is 750 ℃, and the roasting time is 1.5h; and, after crushing and screening in the step (4), the granularity of the flux particles is 20-35 meshes, wherein the granularity of the fine particles above 30 meshes is not more than 20%.
The low-volatility high-heat transfer smelting flux prepared by the embodiment is used for welding, and the welding method and parameters are the same as those of the embodiment 1.
Example 4
The low-volatility high-heat transfer smelting flux provided by the embodiment is prepared from the following components in percentage by mass: siO (SiO) 2 32%，MgO 10%，Al 2 O 3 24%，CaF 2 16%，Fe 2 O 3 11% and B 2 O 3 7%。
The preparation method of the low-volatility high-heat transfer smelting flux provided by the embodiment is the same as that of the embodiment 1.
The low-volatility high-heat transfer smelting flux prepared by the embodiment is used for large heat input welding, and the welding method comprises the following steps: the low-volatility high-heat transfer smelting flux prepared in the embodiment is dried for 2 hours at 260 ℃, and the dried flux is matched with a CHW-S3 welding wire (H10 Mn2 type) to weld the 30mm thick sea work steel EH 550-grade ship plate steel by adopting a tandem double-wire submerged arc welding method. In the welding process, the welding line energy is 60kJ/cm, the stacking height of welding flux is 28mm, the welding speed is 52cm/min, the welding wire distance is 28mm, the welding wire elongation is 24mm, the front wire of the series double-wire submerged arc welding adopts direct current, the welding current/welding voltage of the direct current is 840A/36V, the rear wire of the series double-wire submerged arc welding adopts alternating current, and the welding current/welding voltage of the alternating current is 780A/28V.
The macroscopic morphology of the welded joint section obtained after welding in the embodiment is shown in fig. 1, and it can be seen that the welded joint is attractive in morphology and free of defects such as pores and cracks.
The appearance of the weld bead obtained after the welding in the embodiment is shown in fig. 2, and it can be seen that the surface of the weld bead has no slag adhesion phenomenon, excellent slag detachability and better protection effect on the weld bead.
The microstructure of the welded seam obtained after welding in this example is shown in fig. 3, and it can be seen that austenite grains of the welded seam are fine and the impact toughness is excellent.
Example 5
The low-volatility high-heat transfer smelting flux provided by the embodiment is prepared from the following components in percentage by mass: siO (SiO) 2 31%，MgO 9.5%，Al 2 O 3 26%，CaF 2 16%，Fe 2 O 3 9.5% and B 2 O 3 8%。
The preparation method of the low-volatility high-heat transfer smelting flux provided by the embodiment is the same as that of the embodiment 2.
The low-volatility high-heat transfer smelting flux prepared by the embodiment is used for large heat input welding, and the welding method comprises the following steps: the low-volatility high-heat transfer smelting flux prepared in the embodiment is dried for 2 hours at the temperature of 250 ℃, and the dried flux is matched with a CHW-S3 welding wire (H10 Mn2 type) to weld the 30mm thick marine steel EH 550-grade ship plate steel by adopting a tandem double-wire submerged arc welding method. In the welding process, the welding line energy is 60kJ/cm, the stacking height of welding flux is 30mm, the welding speed is 55cm/min, the welding wire distance is 26mm, the welding wire elongation is 26mm, the front wire of the series double-wire submerged arc welding adopts direct current, the welding current/welding voltage of the direct current is 850A/35V, the rear wire of the series double-wire submerged arc welding adopts alternating current, and the welding current/welding voltage of the alternating current is 760A/33V.
Example 6
The low-volatility high-heat transfer smelting flux provided by the embodiment is prepared from the following components in percentage by mass: siO (SiO) 2 31%，MgO 11%，Al 2 O 3 26%，CaF 2 16%，Fe 2 O 3 10% and B 2 O 3 6%。
The preparation method of the low-volatility high-heat transfer smelting flux provided by the embodiment is the same as that of the embodiment 3.
The low-volatility high-heat transfer smelting flux prepared by the embodiment is used for large heat input welding, and the welding method comprises the following steps: the low-volatility high-heat transfer smelting flux prepared in the embodiment is dried for 1.5 hours at 280 ℃, and the dried flux is matched with a CHW-S3 welding wire (H10 Mn2 type) to weld the 30mm thick sea work steel EH 36-grade ship plate steel by adopting a tandem double-wire submerged arc welding method. In the welding process, the welding line energy is 61kJ/cm, the stacking height of welding flux is 32mm, the welding speed is 50cm/min, the welding wire distance is 26mm, the welding wire elongation is 24mm, the front wire of the series double-wire submerged arc welding adopts direct current, the welding current/welding voltage of the direct current is 870A/36V, the rear wire of the series double-wire submerged arc welding adopts alternating current, and the welding current/welding voltage of the alternating current is 625A/32V.
Example 7
The low-volatility high-heat transfer smelting flux provided by the embodiment is prepared from the following components in percentage by mass: siO (SiO) 2 31%，MgO 10.5%，Al 2 O 3 27%，CaF 2 16%，Fe 2 O 3 9.5% and B 2 O 3 6%。
The preparation method of the low-volatility high-heat transfer smelting flux provided by the embodiment is the same as that of the embodiment 3.
The low-volatility high-heat transfer smelting flux prepared by the embodiment is used for large heat input welding, and the welding method comprises the following steps: the low-volatility high-heat transfer smelting flux prepared in the embodiment is dried for 1.5 hours at 300 ℃, and the dried flux is matched with a CHW-S3 welding wire (H10 Mn2 type) to weld the 30mm thick sea work steel EH 36-grade ship plate steel by adopting a tandem double-wire submerged arc welding method. In the welding process, the welding line energy is 61kJ/cm, the stacking height of welding flux is 34mm, the welding speed is 54cm/min, the welding wire distance is 24mm, the welding wire elongation is 26mm, the front wire of the series double-wire submerged arc welding adopts direct current, the welding current/welding voltage of the direct current is 860A/34V, the rear wire of the series double-wire submerged arc welding adopts alternating current, and the welding current/welding voltage of the alternating current is 740A/34V.
As shown in FIG. 4, the slag shell falling off after welding in the embodiment is very smooth in surface and obvious in scale shape, and the slag shell is shown in FIG. 4, so that the slag removing property of the low-volatility high-heat transfer smelting flux prepared in the embodiment is excellent.
Comparative example 1
The smelting flux provided in this comparative example is made of the following components in mass percent: siO (SiO) 2 35%，Al 2 O 3 27%，CaF 2 19%，Fe 2 O 3 11% and B 2 O 3 8%. That is, the flux does not contain MgO.
The smelting flux provided in this comparative example was prepared in substantially the same manner as in example 1, except that MgO was not added to the raw material.
The welding was performed using the flux prepared in this comparative example, and the welding method and parameters thereof were the same as in example 1.
Comparative example 2
The smelting flux provided in this comparative example is made of the following components in mass percent: siO (SiO) 2 40.5%，MgO 10%，Al 2 O 3 27%，CaF 2 10%，Fe 2 O 3 9.5% and B 2 O 3 3%. Namely, siO in the smelting flux 2 The content is higher.
The smelting flux provided in this comparative example was prepared in the same manner as in example 1.
The welding was performed using the flux prepared in this comparative example, and the welding method and parameters thereof were the same as in example 1.
The EDS diagram of the slag shell falling off after welding in the comparative example is shown in fig. 5, and it can be seen that the slag shell has even element distribution and no element enrichment, and the whole is in an amorphous state. Analysis of the weld structure obtained in this comparative example, as shown in FIG. 6, shows that the grain size is coarse.
This is because of SiO in this comparative example 2 Too high content, relative to CaF 2 B (B) 2 O 3 The content is reduced, the system is compact, and the amorphous forming capability is strong.
Comparative example 3
The smelting flux provided in this comparative example is made of the following components in mass percent: siO (SiO) 2 31%，MgO 7%，Al 2 O 3 31%，CaF 2 16%，Fe 2 O 3 10% and B 2 O 3 5%. Namely, al in the smelting flux 2 O 3 The content is higher.
The smelting flux provided in this comparative example was prepared in the same manner as in example 2.
The welding was performed using the flux prepared in this comparative example, and the welding method and parameters thereof were the same as in example 2.
The morphology of the weld bead obtained after the welding of the comparative example is shown in fig. 7, and it can be seen that the weld bead has obvious pit pressing and slag sticking phenomena. This is because of the higher content of Al 2 O 3 The flux has an excessively large overall viscosity, and thus, the formability during the soldering process is poor.
Comparative example 4
The welding was performed using the smelting flux prepared in example 2, and the welding method was substantially the same as in example 2, except that: the welding current/welding voltage of the direct current was 900A/28V, and the welding current/welding voltage of the alternating current was 990A/32V.
The macro-topography of the welded joint section obtained after the welding of the comparative example is shown in fig. 8. It can be seen that the excessive front and rear wire currents result in large weld penetration and excessive excess, due to the excessively low front wire voltage, with the concomitant generation of holes inside the weld.
Experimental example one test of thermal expansion coefficient, deslagging rate and high-temperature viscosity
The solder fluxes prepared in the above examples and comparative examples were subjected to a deslagging performance test, a thermal expansion coefficient test, and a high-temperature viscosity test, respectively, and the results are shown in table 1.
The deslagging performance test is carried out by adopting a falling ball method, after welding is completed for 10min, a steel ball with the mass of 100g is impacted on a welding line from 1m above a steel plate in a free falling state with the initial speed of 0, flux slag shells falling each time are collected and measured, the slag shells which are not fallen off are cleaned and weighed, and each group is repeated for 3 times.
Viscosity was measured using a rotary viscometer (Brookfield DV2T, bohler, usa). The method comprises the following specific steps: 130g of flux was placed in a molybdenum crucible having an inner diameter of 40mm, a wall thickness of 8mm and a height of 120 mm. Prior to the official test, data of 25 ℃ standard liquid was measured in a thermostatic water tank as calibration, and then the test was started. Placing the molybdenum crucible in a constant temperature area of a high temperature furnace, preserving heat at 1450 ℃, immersing the viscosity measuring head 1cm below the liquid level of the flux melt and starting rotation measurement until the viscosity value exceeds the range, and preventing the measuring head from rotating.
The thermal expansion coefficient was measured by a high temperature thermal expansion tester (PCY-G1700 high temperature thermal expansion coefficient tester, hunan Instrument, hunan pool). The method comprises the following specific steps: samples meeting the thermal expansion size requirement are prepared first before thermal expansion is tested, and 24g of flux is weighed after being dried and divided into three parts with equal mass. The powder in each portion was placed in a 10mm×10mm×50mm rectangular parallelepiped steel mold, and was pressed with a force of 40kN for 20 minutes to obtain a rectangular parallelepiped pressed material. And then placing the pressed material in a muffle furnace, roasting for 2 hours at 1000 ℃, cooling, and taking out to obtain a thermal expansion test sample. Subsequently, the thermally expanded rectangular parallelepiped test piece was placed in a test heating stage, and after calibration and cooling water was passed, the test was started. The coefficient of linear expansion of the test specimen at 1100℃from room temperature was recorded and calculated as follows:
。
Where α is the coefficient of thermal expansion, L is the original length of the sample, dl is the amount of change in the length of the sample during the temperature rise, and dt is the amount of change in temperature.
TABLE 1 thermal expansion coefficient, deslagging rate and high temperature viscosity test results of each flux
As can be seen from Table 1, the thermal expansion coefficient (900 ℃) of the solder prepared in each example is 7.52-8.26X10 -6 Between every two degrees centigrade, the deslagging rate is higher than 91%, so that a good deslagging effect can be achieved; in addition, the welding flux prepared by the embodiments has moderate high-temperature viscosity, can be well covered on the surface of a molten pool, and has the effect of protecting the molten pool.
The flux prepared in each comparative example has a higher thermal expansion coefficient (900 ℃) and a lower deslagging rate, the deslagging effect is poor, and the flux prepared in part of comparative examples has a higher high-temperature viscosity, which leads to poor weld metal formability.
Experimental example two-welded slag shell chemical composition detection
The chemical composition of the skull obtained after welding of each of the above examples and each of the comparative examples was detected by means of X-ray fluorescence spectroscopy, respectively. And the flux of example 1 was prepared by mixing the materials according to the chemical composition, the melting temperature was set at 1550 deg.c, the holding time was set at 2h, and the other parameters were the same as those of example 1, as a control group. The detection results of the chemical components in each group are shown in Table 2, and the content of each component is calculated in mass percent.
TABLE 2 chemical composition detection results of the welded skull of examples and comparative examples
As can be seen from Table 2, in each example, the composition change after melting was small, caF 2 The composition of (2) is stable, the variation range is less than 0.62%, and the physical and chemical properties are stable.
Comparative example 1, in which MgO was not added to the flux, was conductedExacerbating CaF 2 And therefore, the composition of the flux is changed severely after smelting and welding, and the actual production requirement is not met.
Comparative example 3 due to Al in the flux 2 O 3 Too high, resulting in the formation of partial AlF 3 Isogas, thereby causing CaF 2 The content is significantly reduced.
The control group has higher smelting temperature, so that CaF 2 Gas evolution, siF formed 4 The volume of the equal gas is increased, resulting in the decrease of flux yield and the change of physicochemical properties.
Microstructure observation is carried out on the welded seam after the three welding in experimental example
Microstructure observation was performed on the welded joints obtained after the welding of each of the above examples and each of the comparative examples, respectively, and the average lengths of austenite grains in the welded joints were obtained by observation and statistics with a metallographic microscope (OLYMPUS GX51, japan), wherein the average lengths refer to the average value of the lengths of a plurality of austenite grains, and the statistical results are shown in table 3.
TABLE 3 statistics of austenite grain size in welds obtained after each flux weld
As can be seen from Table 3, the weld obtained in each example had a smaller austenite grain size and an average length in the range of 80 μm to 90. Mu.m, whereas the average length of the austenite grains in each comparative example was higher than 110. Mu.m, and reached 127. Mu.m at the maximum.
This means that by controlling the chemical composition of the flux or the welding parameters, the rapid cooling of the weld can be achieved, the resulting weld structure is fine, the effect of fine grain strengthening is achieved, and the toughness of the weld metal can be improved.
Experimental example four mechanical property test
The mechanical properties of the welded joints obtained after the welding of the above examples and comparative examples were tested, including-40 ℃ low-temperature longitudinal impact toughness, tensile strength and elongation, and the test results are shown in table 4.
Wherein, the low-temperature longitudinal impact toughness test at minus 40 ℃ is carried out by a pendulum metal impact tester (SANS-ZBC 2452-C, china) and is carried out by referring to national standard GB/T2650-2008, and the size of a sample is 55mm multiplied by 5mm with V-shaped fracture. Each weld was tested three times for low temperature longitudinal impact toughness at-40 ℃.
Tensile strength and elongation were tested using a tensile tester (Instron 5982, USA), with reference to national standard GB/T2652-2008. Wherein each weld was tested for tensile strength three times.
TABLE 4 mechanical test results for each weld
As can be seen from Table 4, the low temperature impact toughness of the welded seam obtained after welding of the flux prepared in each example is excellent and is far higher than the 27J standard in GB/T5293-2018. The slag detachability, the oxidizing property and the like of the welding flux prepared by the embodiments meet the requirements, and the austenite grains of the welding seam and the alloy elements transiting into the welding seam are fine, so that the toughness of the welding seam is enhanced to a certain extent.
While the impact toughness or tensile strength of each comparative example is lower than that of each example, this demonstrates that controlling the chemical composition of the weld in the present invention has a significant impact on the mechanical properties of the resulting weld after welding.
While the invention has been illustrated and described with reference to specific embodiments, it is to be understood that the above embodiments are merely illustrative of the technical aspects of the invention and not restrictive thereof; those of ordinary skill in the art will appreciate that: modifications may be made to the technical solutions described in the foregoing embodiments, or equivalents may be substituted for some or all of the technical features thereof, without departing from the spirit and scope of the present invention; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions; it is therefore intended to cover in the appended claims all such alternatives and modifications as fall within the scope of the invention.
Claims (9)
1. Low-volatilityThe high heat transfer smelting flux is characterized by being prepared from the following components in percentage by mass: siO (SiO) 2 31%~35%，MgO 9.5%~11%，Al 2 O 3 24%~27%，CaF 2 16%~19%，Fe 2 O 3 9.5% -11% and B 2 O 3 5%~8%；
CaF in raw materials for preparing low-volatility high-heat-transfer smelting flux 2 Mass fraction to CaF in the low-volatility high-heat transfer smelting flux 2 The absolute value of the difference of mass fractions is less than or equal to 0.7%;
the deslagging rate of a welding seam formed after welding by using the low-volatility high-heat transfer smelting flux is more than or equal to 90%;
the average length of austenite grains in a weld joint formed after welding by using the low-volatility high-heat transfer smelting flux is less than or equal to 90 mu m.
2. The low-volatility high-heat transfer smelting flux of claim 1, wherein the low-volatility high-heat transfer smelting flux has a particle size of 8 mesh to 35 mesh.
3. The low-volatility high-heat transfer flux of claim 1, wherein a weld joint formed after welding using the low-volatility high-heat transfer flux has a longitudinal impact toughness of at least 70J at-40 ℃;
the tensile strength of a welding seam formed after welding by using the low-volatility high-heat transfer smelting flux is more than or equal to 665Mpa;
the elongation of the welding seam formed after welding by using the low-volatility high-heat transfer smelting flux is more than or equal to 36%.
4. A method of preparing a low volatility high heat transfer flux as claimed in any one of claims 1 to 3 comprising the steps of:
SiO is made of 2 、MgO、Al 2 O 3 、CaF 2 、Fe 2 O 3 And B 2 O 3 Mixing and smelting to obtain a molten liquid; wherein the smelting temperature<1500℃；
Carrying out water quenching on the melt to obtain a quenched material;
roasting the quenched material, and cooling to obtain the low-volatility high-heat transfer smelting flux.
5. The method for preparing the low-volatility high-heat-transfer smelting flux as claimed in claim 4, wherein the smelting temperature is 1400-1450 ℃, and the smelting heat-preserving time is 0.5-2 h.
6. The method for preparing the low-volatility high-heat transfer smelting flux as claimed in claim 4, wherein the roasting temperature is 650-800 ℃, and the roasting heat preservation time is 1.5-3 h.
7. The method for preparing a low volatility high heat transfer flux as claimed in claim 4 further comprising the steps of crushing and sieving after said firing.
8. The use of a low-volatility high heat transfer flux as claimed in any one of claims 1 to 3 in high heat transfer flux for high heat input welding of steel for marine engineering, wherein the high heat input welding is tandem twin wire submerged arc welding;
The front wire of the series double-wire submerged arc welding adopts direct current, the welding current of the direct current is 800A-870A, and the welding voltage of the direct current is 30V-36V;
the back wire of the series double-wire submerged arc welding adopts alternating current, the welding current of the alternating current is 625A-800A, and the welding voltage of the alternating current is 28V-44V.
9. The use of the low-volatility high-heat transfer smelting flux as claimed in claim 8 in high heat input welding of steel for ocean engineering, wherein the heat input welding has a heat input of 55kJ/cm to 85kJ/cm;
the welding speed of the large heat input welding is 45 cm/min-60 cm/min;
the stacking height of the low-volatility high-heat transfer smelting flux is 21 mm-37 mm;
the welding wire spacing of the series double-wire submerged arc welding is 24 mm-28 mm;
and the elongation of the welding wire of the tandem double-wire submerged arc welding is 24-26 mm.
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