CN104451444B - Low-carbon-equivalent large heat input welding thick steel plate with and preparation method thereof - Google Patents
Low-carbon-equivalent large heat input welding thick steel plate with and preparation method thereof Download PDFInfo
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Abstract
The invention relates to a low-carbon-equivalent large heat input welding thick steel plate and a preparation method thereof. The preparation method comprises the following steps: 1) smelting and casting, wherein the steel plate comprises the following components in percentage by weight: 0.045-0.07% of C, 0.10-0.30% of Si, 1.3-1.6% of Mn, less than or equal to 0.015% of P, 0.001-0.01% of S, 0.2-0.4% of Ni, 0.005-0.035% of Ti, 0.0005-0.01% of Mg, 0.001-0.01% of N, 0.0005-0.005% of B, less than or equal to 0.05% of Al, less than or equal to 0.05% of Ca, less than or equal to 0.02% of REM and the balance of Fe and inevitable impurities and further comprises more than one of less than or equal to 0.03% of Nb or less than or equal to 0.2% of Cr; Ti/N is greater than or equal to 2 but less than or equal to 6, Mg/(Al+Ti) is greater than or equal to 0.024, Ceq is 0.32-0.36% and Bef is 0.0005-0.005%; 2) rolling; 3) cooling. By controlling the (Mg+Ca)/(Al+Ti) ratio and areal density of micron inclusions with the diameter which is greater than or equal to 1 micron as well as the (Mg+Ca)/(Al+Ti) ratio and areal density of submicron inclusions with the diameter which is 0.1-1 micron, for the steel plates with the thickness being 50-70 mm and the base material tensile strength being greater than or equal to 510 MPa, the steel plates are welded with the weld heat input of 200-400kJ/cm, and the average Charpy impact energy of a welding heat affected zone at -40 DEG C reaches 100J above.
Description
Technical field
The present invention relates to welding steel plate manufactures field, can Large Heat Input Welding thickness particularly to a kind of low-carbon-equivalent
Steel plate and its manufacture method.It is 50～70mm for thickness of slab, the steel plate of mother metal tensile strength >=510MPa level, in weld heat input
Under conditions of 200～400kJ/cm, the welding heat affected zone of steel plate has good impact flexibility, -40 DEG C of average Charpy
Ballistic work is in more than 100J.This steel plate can be applied to the neck such as ship, building and oceanic tectonic thing as welding construction material
Domain.
Background technology
In recent years, with the welding structure thing such as shipbuilding, building, pressure vessel, petroleum natural gas pipeline and ocean platform
Maximize, increasingly require to improve the Large Heat Input Welding performance of steel plate, so can improve welding efficiency, shorten and manufacture work
When, reduce manufacturing cost.
After Large Heat Input Welding, the organizational structure of welding heat affected zone steel is destroyed, and austenite crystal is obvious
Grow up, easily form coarse grain zone.Coarse grain zone lead to embrittlement tissue be in cooling procedure formed ferrite side plate, on shellfish
Family name's body, thick grain boundary ferrite and the pearlite being formed in grain boundary ferrite vicinity, between the lath of ferrite side plate
Carbide island-like martensite-austenite constituent element being formed etc..With the increase of weld heat input, original austenite grain particle diameter becomes
Greatly, ferrite side plate and upper bainite tissue are more flourishing, and the size of grain boundary ferrite also accordingly increases, welding heat affected zone
Charpy-V impact power will significantly reduce, it reduce the toughness of welding heat affected zone.
Under the conditions of Large Heat Input Welding, in order to improve the low-temperature flexibility of steel plate welding heat affected zone, forefathers are carried out
Substantial amounts of research work.As Japan Patent JP5116890 (Nintaus's noon, in bright, this Itou Kentaro, Jin Guyan：Enter greatly molten
Connect and make method, JP5116890,1976.5.28 with high dead-wood product.) in disclose in the composition design of steel, add
Plus a certain amount of Ti, N, the deterioration of welding heat influence area toughness can be suppressed using TiN particle, weld heat input can bring up to
50kJ/cm.But when weld heat input reaches more than 200kJ/cm, in welding process, the temperature of welding heat affected zone will
Up to 1400 DEG C, be there is solid solution or grows up by TiN particle in part, and the effect that its suppression welding heat affected zone crystal grain is grown up is by portion
Divide and disappear, welding heat influence area toughness so will be led to deteriorate.Therefore, the steel just with minuteness particle TiN are it is difficult to improve
The Large Heat Input Welding performance of steel plate.
The toughness of steel Large Heat Input Welding heat affected area can also be improved using titanyl compound.This is because the oxygen of titanium
Compound is stable at high temperature, is not susceptible to solid solution.Titanyl compound can play a role as ferritic forming core core simultaneously,
Fining ferrite grains, and form the acicular ferrite structure each other with high inclination-angle crystal grain, be conducive to improving sweating heat
The toughness of the zone of influence.In Japan Patent JP517300, (little Chi permits the method, this expands it, matsuda is clear one, modern times of rectification of name, flat
Occupy just pure, mountain pass Fu Ji, weld handss shadow portion property The ぐ れ material and make method, JP517300,1993.3.8)
In be set forth.But, there are negligible amounts and be difficult to Dispersed precipitate two large problems in steel in titanium oxide.It is it desired to lead to
Cross the quantity to improve titanium oxide for the Ti content improving in steel, the formation that large-scale titanium oxide is mingled with certainly will be led to.Work as titanyl
When the size of compound particle is more than 5 μm, the impact flexibility of mother metal and welding heat affected zone will be reduced.Therefore big in weld heat input
During the Large Heat Input Welding of 200kJ/cm, depend merely on titanyl compound and be still difficult to improve the toughness of welding heat affected zone.
The Japan Patent JP4515430 of Kobe Steel (help two, go out Pu wise man's historical data by high bridge：Weld shadow portion property お
I び mother metal To れ material お I び そ method, JP4515430,2010.5.21.) elaborate by adding
The method that REM, Ca, Zr improve thick plates heat affected area toughness.During Thermal Cycle, even if temperature is up to 1400
DEG C, the oxide being generated using REM, Ca, Zr deoxidation can also in steel Dispersed precipitate and there is not solid solution, thus can hinder
Stop growing up of austenite crystal, thus effectively reducing the size of ferrite crystal grain.When REM, Ca, Zr oxide in field trash
Under conditions of weight percent content is more than 0.3% more than the weight percent content of 5%, Ti oxide, can be significantly
Improve the impact flexibility of welding heat affected zone.
Content of the invention
It is an object of the invention to provide a kind of low-carbon-equivalent can Large Heat Input Welding steel plate and its manufacture method, for
Thickness of slab is 50～70mm, the steel plate of mother metal tensile strength >=510MPa, the condition being 200～400kJ/cm in weld heat input
Under, havevE-40The good welding heat affected zone impact flexibility of >=100J.
For reaching above-mentioned purpose, the technical scheme is that：
A kind of low-carbon-equivalent of the present invention can Large Heat Input Welding steel plate, its chemical component weight percentage ratio is：C
0.045～0.07%, Si 0.10～0.30%, Mn 1.3～1.6%, P≤0.015%, S 0.001～0.01%, Ni 0.2
～0.4%, Ti 0.005～0.035%, Mg 0.0005～0.01%, N 0.001～0.01%, B 0.0005～
0.005%, Al≤0.05%, Ca≤0.005%, REM≤0.02%, remaining is Fe and inevitable impurity；Wherein, 2≤Ti/
N≤6, Mg/ (Al+Ti) >=0.024；
And in steel plate,
Carbon equivalent Ceq0.32%～0.36%, Ceq=C+Mn/6+ (Cr+Mo+V)/5+ (Ni+Cu)/15；
Effectively boron amount Bef0.0005～0.005%, wherein,
When N-Ti × 14.01/47.87≤0, Bef=B；
As N-Ti × 14.01/47.87>When 0, Bef=B- (N-Ti × 14.01/47.87) × 10.81/14.01.
Further, the chemical composition of steel plate of the present invention also contains one kind in Nb 0.001～0.03% or Cr≤0.2%
Above element, by weight percentage.
In steel plate, for diameter greater than the micron field trash equal to 1 μm, it is mingled with surface density >=100/mm2, chemistry
Composition meets (Mg+Ca)/(Al+Ti) >=1.8.For a diameter of 0.1-1 μm of submicron field trash, be mingled with surface density >=
220/mm2, chemical composition satisfaction (Mg+Ca)/(Al+Ti) >=1.1.
In the composition design of steel of the present invention,
C, is to increase the element of steel strength.For the TMCP technique of controlled rolling and controlled cooling, in order to stably keep specific
Intensity, the lower limit of C content is 0.045%.But excessively add C, the toughness leading to mother metal and welding heat affected zone reduced,
The upper limit of C content is 0.07%.
Si, is required element during steel-making pre-deoxidation, and can play the effect of strengthening mother metal, and therefore Si contains
The lower limit of amount is 0.1%.But the toughness of mother metal when Si too high levels are more than 0.3%, can be reduced, simultaneously in Large Heat Input Welding
During, the generation of island-like martensite-austenite constituent element will be promoted, significantly reduce welding heat influence area toughness.Si content range
For 0.10～0.30%.
Mn, can be improved the intensity of mother metal, can play a role as pre-deoxidation element again by solution strengthening.Simultaneously
The precipitation of MnS can promote the generation of Intragranular Acicular Ferrite, and the lower limit of Mn is 1.3%.But too high Mn will lead to slab
Center segregation, can lead to the hardening of Large Heat Input Welding heat affected area and MA to generate simultaneously, reduce the toughness of welding heat affected zone,
So the higher limit of Mn is controlled to 1.6%.
Ti, by forming Ti2O3Particle, can promote the generation of Intragranular Acicular Ferrite.Ti is combined generation TiN particle with N simultaneously
Can growing up in welding heat affected zone pinning austenite crystal, make mother metal and welding heat affected zone structure refinement, improve toughness.
So as beneficial element, the lower limit of Ti content is 0.005%.But during Ti too high levels, thick nitride will be formed, or
Person promotes the generation of TiC, reduces the toughness of mother metal and welding heat affected zone, so Ti upper content limit is 0.035%.
Mg, the MgO that interpolation Mg can generate fine dispersoid distribution is mingled with, and is mingled with as forming core core using these, can promote
Enter the precipitation of TiN and MnS, the growing up and promote the growth of Intragranular Acicular Ferrite of austenite crystal during suppression Thermal Cycle,
Improve the toughness of welding heat affected zone.Mg content in steel is advisable with 0.0005-0.01%.When Mg content is less than 0.0005%
When, the quantity of the microinclusions of generation will substantially reduce, and the Mg content in microinclusions significantly reduces it is impossible to expire simultaneously
Foot separates out the requirement of MnS, TiN on field trash surface.If Mg content is more than the effect saturation of 0.01%, Mg, increase simultaneously
Evaporation loss and the oxidational losses of Mg are added.
It is a discovery of the invention that there is the relation of competition deoxidation, when Mg content is too low, Al in Al and Ti in the Mg and molten steel that add
During with Ti too high levels, it is unfavorable for generating the field trash with MgO as main component, for this reason, Mg, the Al and Ti content in steel will expire
Sufficient Mg/ (Al+Ti) >=0.024.
N, can form fine Ti nitride, during Large Heat Input Welding, can effectively suppress austenite crystal
Grain grow up, its lower limit be 0.001%.But its content is more than 0.006%, the formation of solid solution N will be led to, reduce mother metal and weldering
Connect the toughness of heat affected area.
Meanwhile, there is in steel to be kept suitable Ti/N ratio, its ratio is 2≤Ti/N≤6.When Ti/N is less than 2,
The quantity of TiN particle will drastically reduce it is impossible to form sufficient amount of TiN particle, during suppressing Large Heat Input Welding
Growing up of austenite crystal, reduces the toughness of welding heat affected zone.When Ti/N is more than 6, TiN particle coarsening, mistake simultaneously
Surplus Ti is easily combined with C and generates thick TiC particle, and these thick particles are possible as the starting point of crackle generation,
Reduce the impact flexibility of mother metal and welding heat affected zone.
Al, when Al content is too high in steel, easily generates tufted alumina inclusion, is unfavorable for fine dispersoid distribution field trash
Generation.Therefore, the upper limit of Al content is 0.05%.
Ca, adds the form that Ca can improve sulfide, and the oxide of Ca and sulfide can also promote Intragranular Acicular Ferrite
Growth, the oxide combination of the oxide of Ca and Al can form the field trash of low melting point, improve the form of field trash.If
Ca content is more than the effect saturation of 0.005%, Ca, increased evaporation loss and the oxidational losses of Ca simultaneously.Therefore, Ca contains
The upper limit of amount is 0.005%.
The interpolation of REM, REM can improve the form of sulfide, and the oxide of REM and sulfide can suppress to weld simultaneously
In Thermal Cycling, austenite crystal grows up.But, when the content of REM is more than 0.02%, generating portion particle diameter is more than 5 μm
Field trash, reduce the impact flexibility of mother metal and welding heat affected zone.Therefore, the upper limit of REM content is 0.02%.
S, in the adding procedure of Ca and/or REM, forms sulfide with Ca and/or REM, can also promote MnS in oxidation
On thing particle, or the precipitation further in Ca and REM sulfide particles, thus promoting the formation of Intragranular Acicular Ferrite, its lower limit
For 0.001%.But, its too high levels, the center segregation of slab will be led to.In addition, when S content is more than 0.01%, it will
The thick sulfide of forming part, the starting point that these thick sulfide will be formed as crackle, reduces mother metal and sweating heat
The impact flexibility of the zone of influence.Therefore, the upper limit of S content is 0.01%.
P, is the impurity element in steel, should reduce as far as possible.Its too high levels, will lead to center segregation, reduce welding hot shadow
Ring the toughness in area, the upper limit of P is 0.015%.
Ni, can improve intensity and the toughness of mother metal, and its lower limit is 0.2%.But because it is expensive, in view of cost
Restriction, be limited to 0.4% thereon.
Nb, can refine the tissue of steel, improve intensity and toughness.But because it is expensive, in view of the limit of cost
System, its composition range is 0.001～0.03%.
Cr, can improve the quenching degree of steel.For steel plate, improve quenching degree and can make up the intensity that thickness brings
Loss, improves the intensity of thickness of slab central area, improves the uniformity of performance on thickness direction.But too high Cr and Mn adds simultaneously
Fashionable, the Cr-Mn composite oxides of low melting point can be formed, easily form face crack in the hot rolling, also can affect simultaneously
The welding performance of steel.Therefore Cr upper content limit is 0.2%.
Ceq, carbon equivalent directly affects the tensile strength of mother metal, and typically with the increase of carbon equivalent, the tensile strength of mother metal adds
Greatly.On the other hand, carbon equivalent directly affects the impact flexibility of welding heat affected zone again, with the increase of carbon equivalent, welds hot shadow
The impact flexibility ringing area reduces.The present invention is found by research, in order to meet the requirement of mother metal tensile strength >=510MPa simultaneously,
And under weld heat input is for 200～400kJ/cm welding condition, the average Charpy punching of -40 DEG C of the welding heat affected zone of steel plate
Hit the requirement that work(reaches more than 100J, carbon equivalent needs to control in rational scope.When carbon equivalent is less than 0.32%, mother metal
Tensile strength can not meet the requirement more than or equal to 510MPa；When carbon equivalent is more than 0.36% it is impossible to meet in sealing wire energy
Measure as under 200～400kJ/cm welding condition, the average Charpy-V impact power of -40 DEG C of the welding heat affected zone of steel plate reach 100J with
On requirement.
B, is to improve the effective element of quenching degree, can promote the formation of bainite structure, improve thickness of slab central area
Tensile strength.Meanwhile, by forming BN, the growth of Intragranular Acicular Ferrite can be promoted.As solid solution B, after welding cooled
In journey, segregation, in austenite grain boundary, can also suppress the generation of grain boundary ferrite.Therefore in order to ensure intensity and the raising of mother metal
The impact flexibility of welding heat affected zone, the lower limit of B content is 0.0005%.Quenching degree will be led to when but B content is too high notable
Rise, reduce toughness and the ductility of mother metal, reduce the toughness of welding heat affected zone, its upper limit is 0.005% simultaneously.
Bef, according to N element adhesion size in steel, the N in steel combines to form TiN with Ti first, and remaining N will be with B
Combine to form BN.So deduct the B content being combined with N, remaining B is effective boron content.Therefore effectively boron (Bef) can define
As follows：
When N-Ti × 14.01/47.87≤0, Bef=B；
As N-Ti × 14.01/47.87>When 0, Bef=B- (N-Ti × 14.01/47.87) × 10.81/14.01.
Effective boron content directly affects the quenching degree of steel, for the intensity improving thickness of slab central area, improves thickness side
The uniformity of performance is extremely important upwards.The study find that, effective boron amount needs to control in rational scope, could expire simultaneously
The requirement of the tensile strength of sufficient mother metal, mother metal and welding heat affected zone impact flexibility.When effective boron be less than 0.0005% when it is impossible to
Meet carbon equivalent CeqUnder conditions of 0.32%～0.36%, mother metal tensile strength is more than or equal to the requirement of 510MPa；When effective
When boron is more than 0.005%, the impact flexibility of mother metal and welding heat affected zone will be reduced.
Research discovery is carried out to the impact flexibility of steel plate welding heat affected zone under the conditions of raising Large Heat Input Welding,
Under conditions of Mn, Si, Ti, Al, Mg, Ca and REM complex deoxidization, can promote with diameter greater than the microns oxide grain equal to 1 μm
A large amount of generations of son, easily separate out MnS, TiN on their surface, thus can induce the formation of Intragranular Acicular Ferrite.In addition, also
A large amount of generations of the submicron field trash such as a diameter of 0.1-1 μm nitride, sulfide can be promoted, these submicron field trashes
Growing up of austenite crystal can be suppressed during Large Heat Input Welding, therefore can significantly improve welding heat affected zone
Impact flexibility.
Present invention determine that the suitable component of field trash and quantity.The components utilising SEM-EDS of field trash is analyzed, right
In sample be ground with mirror finish after, using SEM, field trash is observed and is analyzed, each specimen holder debris
Composition is the meansigma methodss 10 arbitrarily being chosen to inclusion analysis result.Using SEM under 1000 times of multiplying power for 50
Continuous visual field of choosing is observed, and observed visual field area is more than 0.27mm2.The surface density of field trash is observed being mingled with
Thing quantity and the result of calculation of visual field area.
The present invention is found by substantial amounts of experimental study, and the micron being more than or equal to 1.0 μm for particle diameter in steel is mingled with
Thing, when the ratio of (Mg+Ca) in field trash/(Al+Ti) weight percent content is more than or equal to 1.8, in field trash
MgO, CaO oxide components are higher, and the oxide simultaneously easily forming Mg-Ca-Al-Ti is core, and MnS, TiN and BN are being mingled with
Beyond the region of objective existence encloses the complex inclusion of precipitation.Such micron field trash, one side easily Dispersed precipitate in steel, be conducive to being mingled with
The increase of thing quantity；On the other hand, the generation of the Intragranular Acicular Ferrite with field trash as core can be promoted, thus improving steel plate
Large Heat Input Welding performance.At the same time it can also suppress the tufted aluminate with Al as main component, or large-scale oxygen
Change the formation of aluminum inclusion, improve welding heat influence area toughness.This is because tufted and the easy conduct of large-scale alumina inclusion are split
The starting point that stricture of vagina generates leads to the generation of crackle, reduces Low Temperature Impact Toughness of Heat-affected Zone.Additionally, the surface density when micron field trash
Less than 100/mm2When, micron field trash can not play the effect of induction Intragranular Acicular Ferrite growth effectively.Accordingly, it would be desirable to control
Micron composition of inclusions processed, makes (Mg+Ca)/(Al+Ti) >=1.8, surface density >=100/mm2.
The submicron field trash being 0.1～1.0 μm for particle diameter in steel, (Mg+Ca)/(Al+Ti) weight percent content
Ratio when being more than or equal to 1.1, the submicron field trash of this composition, be conducive to Dispersed precipitate, promote a large amount of submicrons folders
The formation of debris.During Thermal Cycle, such submicron inclusion particle can effectively pinning welding heat affected
Growing up of area's austenite crystal, improves the toughness of welding heat affected zone.When the surface density of submicron field trash is less than 220/mm2
When, submicron field trash can not play the effect of pinning welding heat affected zone Austenite Grain Growth effectively.Accordingly, it would be desirable to control
Submicron field trash processed is formed so as to composition meets (Mg+Ca)/(Al+Ti) >=1.1, surface density >=220/mm2.
Low-carbon-equivalent of the present invention can Large Heat Input Welding steel plate manufacture method, comprise the steps：
1) smelt, cast
By following compositions smelting, refine, it is casting continuously to form base, the chemical component weight percentage ratio of steel is：
C 0.045～0.07%, Si 0.10～0.30%, Mn 1.3～1.6%, P≤0.015%, S 0.001～
0.01%, Ni 0.2～0.4%, Ti 0.005～0.035%, Mg 0.0005～0.01%, N 0.001～0.01%, B
0.0005～0.005%, Al≤0.05%, Ca≤0.005%, REM≤0.02%, remaining is Fe and inevitable impurity, steel
The chemical composition of plate meets 2≤Ti/N≤6, Mg/ (Al+Ti) >=0.024；
And in steel plate, carbon equivalent Ceq：0.32%～0.36%, effective boron amount Bef：0.0005～0.005%；Its
In, Ceq=C+Mn/6+ (Cr+Mo+V)/5+ (Ni+Cu)/15.When N-Ti × 14.01/47.87≤0, Bef=B；When N-Ti ×
14.01/47.87>When 0, Bef=B- (N-Ti × 14.01/47.87) × 10.81/14.01；
2) roll
By heating strand to 1050～1250 DEG C, breaking down temperature is higher than 930 DEG C, and accumulative reduction ratio is more than 30%；Finish rolling temperature
Degree is less than 930 DEG C, and accumulative reduction ratio is more than 30%；
3) cool down
Surface of steel plate temperature is begun to cool down to less than 500 DEG C by the rate of cooling using 1-30 DEG C/s from more than 750 DEG C.
Further, the chemical composition of described steel plate also contain in Nb 0.001～0.03% or Cr≤0.2% a kind of with
Upper element, by weight percentage.
In steel plate, for diameter greater than the micron field trash equal to 1 μm, it is mingled with surface density >=100/mm2, chemistry
Composition meets (Mg+Ca)/(Al+Ti) >=1.8；For a diameter of 0.1-1 μm of submicron field trash, be mingled with surface density >=
220/mm2, chemical composition satisfaction (Mg+Ca)/(Al+Ti) >=1.1.
The present invention obtain steel plate thickness of slab 50～70mm, mother metal tensile strength >=510MPa, weld heat input be 200～
Under 400kJ/cm welding condition, the average Charpy-V impact power in -40 DEG C of welding heat affected zone of steel plate reaches more than 100J.
The present invention rolling and cooling technique in,
When heating-up temperature before rolling is less than 1050 DEG C, the carbonitride of Nb can not solid solution completely.When heating-up temperature is more than
When 1250 DEG C, growing up of austenite crystal will be led to.
Breaking down temperature is higher than 930 DEG C, and accumulative reduction ratio is more than 30%, is because, more than this temperature, recrystallizing, can
With fining austenite grains.When accumulative reduction ratio is less than 30%, the thick austenite crystal formed in heating process also can
Remaining, reduces the toughness of mother metal.
Final rolling temperature is less than 930 DEG C, and accumulative reduction ratio is more than 30%, is because that at such temperatures, austenite is not sent out
Life recrystallizes, the dislocation formed in the operation of rolling, can work as the core of ferrite forming core.When accumulative reduction ratio is little
When 30%, the dislocation being formed is less, is not enough to induce the forming core of acicular ferrite.
The rate of cooling of 1-30 DEG C/s is adopted to begin to cool down to 500 surface of steel plate temperature from more than 750 DEG C after finish rolling
Below DEG C, to ensure that mother metal has suitable intensity and toughness.When rate of cooling is less than 1 DEG C/s, the intensity of mother metal declines, no
Can meet and require；When rate of cooling is more than 30 DEG C/s, the toughness of mother metal reduces it is impossible to meet requirement.
Beneficial effects of the present invention：
The present invention takes suitable composition design and Control and Inclusion Removal technology, by for Ti/N in steel, Mg/ (Al+Ti)
Ratio, BefAnd CeqRationally controlled, and for diameter greater than the surface density of the micron field trash equal to 1 μm and chemical composition
(Mg+Ca)/(Al+Ti) ratio, the surface density of submicron field trash of 0.1-1 μm of diameter and chemical composition (Mg+Ca)/(Al+
Ti) ratio is rationally controlled, and in solidification and phase transition process, can promote the life of Intragranular Acicular Ferrite on these field trash surfaces
Long, or suppress growing up of austenite crystal, improve the Large Heat Input Welding performance of steel plate.Steel plate thickness manufactured by the present invention
Specification be 50～70mm, mother metal tensile strength >=510MPa, weld heat input be 200～400kJ/cm welding condition under,
Welding heat affected zone hasvE-40The good Large Heat Input Welding performance of >=100J.
Specific embodiment
With reference to embodiment, the present invention will be further described.
Table 1 is the chemical composition of the embodiment of the present invention and comparative example, Ti/N, Bef、CeqWith Mg/ (Al+Ti) ratio.Table 2 is
The mother metal mechanical property of the embodiment of the present invention and comparative example, field trash characteristic and welding heat affected zone impact flexibility.
Low-carbon-equivalent of the present invention can the manufacture method of Large Heat Input Welding steel plate be：Smelting, refine and continuous casting, obtain
The chemical composition of strand is as shown in table 1；Then by heating strand to 1050 DEG C～1250 DEG C, breaking down temperature is 1000～1150
DEG C, accumulative reduction ratio is 50%；Final rolling temperature is 700～850 DEG C, and accumulative reduction ratio is 53～67%%；Adopt after finish rolling
Surface of steel plate temperature is begun to cool down to less than 500 DEG C by the rate of cooling of 4-8 DEG C/s from more than 750 DEG C, to ensure that mother metal has
Suitable intensity and toughness.
A time welding is implemented for the steel plate of different-thickness using electro-gas (enclosed) welding, weld heat input is 200～400kJ/
cm.Impact specimen is taken on the melt run of thickness of slab 1/2, imports v-notch and carry out impact flexibility detection, carry out at -40 DEG C
The Charpy-type test of three samples, the data of welding heat affected zone impact flexibility is the meansigma methodss of three measurement results.
From Tables 1 and 2, in embodiment, according to determined by the present invention, chemical composition ranges carry out Composition Control, and
And control Ti/N ratio to be 2≤Ti/N≤6, and Mg/ (Al+Ti) >=0.024, carbon equivalent Ceq0.32%～0.36%, effective boron amount
Bef：0.0005～0.005%.In addition, controlling with diameter greater than the micron field trash equal to 1 μm, surface density >=100/mm2, change
Study point satisfaction (Mg+Ca)/(Al+Ti) >=1.8；A diameter of 0.1-1 μm of submicron field trash, surface density >=220/mm2,
Chemical composition meets (Mg+Ca)/(Al+Ti) >=1.1.
In comparative example 1～3, in steel, Mg content is respectively less than 0.0005%, all can not meet Mg/ (Al+Ti) >=0.024
Requirement.Comparative example 2 and 3 can not meet effective boron amount Bef：0.0005～0.005% component requirements.Meanwhile, comparative example 1 to 3
The surface density with diameter greater than the micron field trash equal to 1 μm and (Mg+Ca)/(Al+Ti) ratio, a diameter of 0.1-1 μ can not be met
The surface density of submicron field trash of m and the requirement of (Mg+Ca)/(Al+Ti) ratio.In addition, in comparative example 3, Ti/N ratio is not
The requirement of the present invention can be met.
Table 2 lists the tensile property of mother metal and impact flexibility in embodiment and comparative example, and welding heat affected zone
Impact flexibility.The yield strength of mother metal, tensile strength and percentage elongation are the meansigma methodss of test data twice, mother metal and welding hot shadow
Ring the meansigma methodss that -40 DEG C of area Charpy-V impact power is three test datas.
As can be seen from the table, the mother metal mechanical property of embodiment and comparative example does not have obvious difference, Dou Nengman
The thickness specification of steel plate manufactured by foot is 50～70mm, the requirement of mother metal tensile strength >=510MPa.It is 200 in weld heat input
Under conditions of～400kJ/cm, -40 DEG C of welding heat affected zone Charpy-V impact power is tested, the value of embodiment 1～8 is divided
It is not 152,168,225,102,186,122,157,220 (J), the value of comparative example 1,2,3 is 12,17,7 (J).Embodiment is welded
The impact flexibility of heat affected area is significantly improved, and can meet the requirement of 200～400kJ/cm Large Heat Input Welding.
The present invention takes suitable composition design it is determined that suitable Ti/N and Mg/ (Al+Ti) ratio in steel, and
BefAnd Ceq, and it is mingled with surface density and chemical composition (Mg+Ca)/(Al+Ti) ratio for diameter greater than the micron equal to 1 μm,
A diameter of 0.1-1 μm of submicron is mingled with surface density and chemical composition (Mg+Ca)/(Al+Ti) ratio is rationally controlled, this
Sample can promote the growth of Intragranular Acicular Ferrite in solidification and phase transition process on these field trash surfaces, or suppression austenite crystal
Grow up, improve the Large Heat Input Welding performance of steel plate.The thickness specification of manufactured steel plate is 50～70mm, mother metal tension
Intensity >=510MPa, is that under 200～400kJ/cm welding condition, welding heat affected zone has in weld heat inputvE-40≥100J
Good Large Heat Input Welding performance.This technology can be used in the manufacture processes of steel plate such as ship, building and oceanic tectonic thing,
For improving the Large Heat Input Welding performance of steel plate.
Claims (6)
1. a kind of low-carbon-equivalent can Large Heat Input Welding steel plate, its chemical component weight percentage ratio is：
C 0.045～0.07%,
Si 0.10～0.30%,
Mn 1.3～1.6%,
P≤0.015%,
S 0.001～0.01%,
Ni 0.2～0.4%,
Ti 0.005～0.035%,
Mg 0.0005～0.01%,
N 0.001～0.01%,
B 0.0005～0.005%,
Al≤0.05%,
Ca≤0.005%,
REM≤0.02%,
Remaining is Fe and inevitable impurity；Wherein, 2≤Ti/N≤6, Mg/ (Al+Ti) >=0.024；
And in steel plate,
Carbon equivalent Ceq：0.32%～0.36%, Ceq=C+Mn/6+ (Cr+Mo+V)/5+ (Ni+Cu)/15；
Effectively boron amount Bef：0.0005～0.005%；
When N-Ti × 14.01/47.87≤0, Bef=B；
As N-Ti × 14.01/47.87>When 0, Bef=B- (N-Ti × 14.01/47.87) × 10.81/14.01；
For with diameter greater than the micron field trash equal to 1 μm, it is mingled with surface density >=100/mm2, chemical composition satisfaction (Mg+
Ca)/(Al+Ti)≥1.8；For a diameter of 0.1-1 μm of submicron field trash, it is mingled with surface density >=220/mm2, chemistry
Composition meets (Mg+Ca)/(Al+Ti) >=1.1.
2. low-carbon-equivalent as claimed in claim 1 can Large Heat Input Welding steel plate, it is characterized in that, the change of described steel plate
Study and point also contain one or more elements in Nb 0.001～0.03% or Cr≤0.2%, by weight percentage.
3. low-carbon-equivalent as claimed in claim 1 or 2 can Large Heat Input Welding steel plate, it is characterized in that, described steel plate
Mother metal tensile strength >=510MPa, is the welding heat affected zone of steel plate under 200～400kJ/cm welding condition in weld heat input
In -40 DEG C of average Charpy-V impact powers in more than 50J.
4. a kind of low-carbon-equivalent can Large Heat Input Welding steel plate manufacture method, comprise the steps：
1) smelt, cast
By following compositions smelting, refine, it is casting continuously to form base, the chemical component weight percentage ratio of steel is：C 0.045～0.07%, Si
0.10～0.30%, Mn 1.3～1.6%, P≤0.015%, S 0.001～0.01%, Ni 0.2～0.4%, Ti 0.005
～0.035%, Mg 0.0005～0.01%, N 0.001～0.01%, B 0.0005～0.005%, Al≤0.05%, Ca≤
0.005%, REM≤0.02%, remaining is Fe and inevitable impurity；This chemical composition meets 2≤Ti/N≤6, Mg/ (Al+
Ti)≥0.024；And,
In steel plate, carbon equivalent Ceq：0.32%～0.36%,
Ceq=C+Mn/6+ (Cr+Mo+V)/5+ (Ni+Cu)/15；
Effectively boron amount Bef：0.0005～0.005%；
When N-Ti × 14.01/47.87≤0, Bef=B；
As N-Ti × 14.01/47.87>When 0, Bef=B- (N-Ti × 14.01/47.87) × 10.81/14.01；
In steel plate, for diameter greater than the micron field trash equal to 1 μm, it is mingled with surface density >=100/mm2, chemical composition
Meet (Mg+Ca)/(Al+Ti) >=1.8；For a diameter of 0.1-1 μm of submicron field trash, be mingled with surface density >=220/
mm2, chemical composition satisfaction (Mg+Ca)/(Al+Ti) >=1.1；
2) roll
By heating strand to 1050～1250 DEG C, breaking down temperature is higher than 930 DEG C, and accumulative reduction ratio is more than 30%；Final rolling temperature is little
In 930 DEG C, accumulative reduction ratio is more than 30%；
3) cool down
Surface of steel plate temperature is begun to cool down to less than 500 DEG C by the rate of cooling using 1-30 DEG C/s from more than 750 DEG C.
5. low-carbon-equivalent as claimed in claim 4 can Large Heat Input Welding steel plate manufacture method, it is characterized in that, described
The chemical composition of steel plate also contains one or more elements in Nb 0.001～0.03% or Cr≤0.2%, with weight
Percentages.
6. the low-carbon-equivalent as described in claim 4 or 5 can Large Heat Input Welding steel plate manufacture method, it is characterized in that,
The steel plate mother metal tensile strength >=510MPa obtaining, is the weldering of steel plate under 200～400kJ/cm welding condition in weld heat input
The average Charpy-V impact power connecing heat affected area at -40 DEG C is in more than 50J.
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| CN110421285B (en) * | 2019-06-27 | 2020-12-25 | 江苏省沙钢钢铁研究院有限公司 | Evaluation method for large heat input resistance of magnesium-containing steel plate |
| CN111926259B (en) * | 2020-08-20 | 2021-08-03 | 钢铁研究总院 | Low alloy steel for high heat input welding and preparation method thereof |
| CN113444975B (en) * | 2021-07-02 | 2022-05-17 | 东北大学 | Pre-heating-free high-strength hydroelectric steel with low carbon equivalent weight of 600MPa grade before welding and manufacturing method thereof |
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