CN104066858A - Process for producing tapered plate - Google Patents

Process for producing tapered plate Download PDF

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Publication number
CN104066858A
CN104066858A CN201280067544.9A CN201280067544A CN104066858A CN 104066858 A CN104066858 A CN 104066858A CN 201280067544 A CN201280067544 A CN 201280067544A CN 104066858 A CN104066858 A CN 104066858A
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quality
welding
toughness
thickness
plate
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CN201280067544.9A
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CN104066858B (en
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横田智之
中村雅美
长谷和邦
三田尾真司
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JFE Steel Corp
JFE Engineering Corp
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NKK Corp
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    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/14—Ferrous alloys, e.g. steel alloys containing titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0263—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment following hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium

Abstract

A process for producing a tapered plate which permits high heat input welding with a welding heat input exceeding 300kJ/cm and which exhibits a tensile strength of 570MPa or more is provided. Specifically, this process comprises: heating a steel slab which contains, in mass %, 0.03 to 0.12% of C, 0.03 to 0.5% of Si, 0.8 to 2.2% of Mn, at most 0.015% of P, 0.0005 to 0.0050% of S, 0.005 to 0.1% of Al, 0.003 to 0.014% of Nb, 0.003 to 0.02% of Ti, 0.0003 to 0.0025% of B, 0.0030 to 0.0070% of N and 0.0005 to 0.005% of Ca with the balance being Fe and unavoidable impurities and which satisfies the relationship (1) to a temperature of 1000 to 1200 DEG C; subjecting the resulting slab to hot-rolling with the finishing rolling temperature ranging from the Ar3 temperature to 900 DEG C to convert the slab into a tapered plate of which the plate thickness decreases longitudinally; and then subjecting the tapered plate to accelerated cooling to lower the temperature of the tapered plate to 500 DEG C or lower. 0 <=N-Ti/3.42<= 0.0025 [wherein N and Ti represent the contents (mass%) thereof respectively] (

Description

The manufacture method of taper plate
Technical field
The present invention relates to be suitable for shipbuilding (shipbuilding), building (architecture) etc., thickness of slab along its length continually varying taper plate (tapered plate) (also referred to as wedge-like steel plate (tapered steel plates), LP steel plate (Longitudinally Profiled Steel Plate)) manufacture method, relate to intensity difference in steel plate few, and welding heat input (welding heat input) exceedes, and the height input heat welding (high-heat input welding) of 300kJ/cm can be suitable for, tensile strength (tensile strength) is more than 570MPa, and there is in the longitudinal direction the manufacture method of the taper plate of poor (thickness of slab poor (the difference of steel platethickness)) of more than 10mm thick portion thickness and thin portion thickness.
Background technology
The shape of Plate Steel is all uniform conventionally on width and length direction.But when thickness of slab is changed along its length continuously, during sometimes to the alleviating of former material weight (material weight), Welder, the reduction of (welding man-hour) has larger effect.Such Plate Steel is called taper plate, wedge-like steel plate or LP steel plate etc., and about its manufacture method, patent documentation 1, patent documentation 2 and patent documentation 3 etc. have multiple motion.These motions are to manufacture taper plate as object using high dimensional accuracy (dimensional accuracy).But, except dimensional precision, if the homogeneity (material uniformity) of the material characteristic of steel plate (material property) and material can not meet, can not tolerate practical application.
Recently, it is strict that the quality requirements (quality demand) to Plate Steel becomes, and particularly the raising of the requirement of high strength and weldability (weldability) requires to smarten.For such requirement, adopt controlled rolling (controlled rolling) and cooling (controlled cooling) such TMCP method (Thermo-Mechanical Control Process, thermomechanical control technique) of control.The method is by the austenite → ferrite transformation (ferrite transformation) after work (heavy reduction) and its of forcing in austenite non-recrystallization region (no-recrystallization temperature range in austenite) or (austenite+ferrite (ferrite)) two phase regions, realize the microminiaturization of ferrite crystal grain (ferritic grain), and then carry out as required coolingly, further realize high strength, high tenacity.
But when the method is applied to taper plate, (temperature control) is extremely difficult for temperature treatment, material variation (variation of material property) increases.
Particularly controlled rolling is in the situation of forcing work under the such low temperature of the region rolling of austenite non-recrystallization and (austenite+ferrite) two phase region rollings (dual phase rolling, dual-phase rolling), when as taper plate, in thickness of slab direction, thickness is different, the temperature head of the steel billet temperature of thin portion and thick portion becomes excessive, the problem that exists the difference of intensity to increase.In order to eliminate inhomogeneous (the inhomogeneous of material) of such material, manufacture the taper plate of homogeneous, carry out some motions.
For example, a kind of method of cooling of taper plate is disclosed in patent documentation 4, it is in order to obtain uniform material, survey the distribution of the temperature of cooling front length direction, based on this measured value, the Investigation of Optimum Cooling Condition (optimum cooling condition) of computing each point, the plate speed (conveying speed) when cooling according to thickness of slab correction.The method of cooling that begins to cool down simultaneously, also changes the taper plate in the period that occurs refrigerating unit is disclosed in patent documentation 5 in thin portion and the thick portion of steel plate, or the cooling method of cooling that starts successively and finish simultaneously cooling taper plate along steel plate length direction.All in the motion of accelerating to reduce when cooling the deviation (variation of material property) of the material in steel plate.
On the other hand, as the example that is grouped into attempt solving such technical problem by the one-tenth of design steel plate, there is patent documentation 6.In this technology, disclose by Nb addition is risen to 0.015%～0.06%, the deviation (scatter of strength) of intensity is reduced.
In addition, if disclose and made by Hv in patent documentation 7 20-50the Hv that=-110+460C+44Si+39Mn-31Cu-9Ni+11Cr+22Mo+180V+9600B-23000Mo × B represents 20-50value (taking the Hv hardness when the suitable speed of cooling of the cooling rate (air cooling) at 800～500 DEG C of the steel plate of 20mm and 50mm is cooled to normal temperature with thickness of slab poor), as below 15, makes the deviation of intensity reduce.
But, in recent years, in the steel that the height input heat welding (high-heat inputwelding) of increasing in its demand can be applicable, in order to ensure the toughness of weld part, restrict upper existence of various Composition Designs (alloy design), therefore, as taper plate, be not easy from the Composition Design of viewpoint that reduces strength variance, particularly weld the steel of use at the height input heat that contains B, exist according to the deviation tendency of the variation of thickness of slab and finishing temperature (finishing temperature), intensity and become the problem showing.
Prior art document
Patent documentation
Patent documentation 1: Japanese Patent Publication 50-36826 communique
Patent documentation 2: Japanese Patent Publication 60-124 communique
Patent documentation 3: Japanese Patent Publication 5-49361 communique
Patent documentation 4: Japanese kokai publication sho 62-166013 communique
Patent documentation 5: Japanese kokai publication hei 7-68309 communique
Patent documentation 6: No. 3180944 communique of Japanese Patent
Patent documentation 7: No. 3972553 communique of Japanese Patent
Summary of the invention
The problem that invention will solve
The object of the invention is to, advantageously address the above problem, provide tensile strength (tensilestrength) for 570MPa is above, the deviation of intensity is little and welding heat input (weldingheat input) exceedes thick portion thickness good-toughness, length direction of weld part of height input heat of 300kJ/cm and poor (tilt quantity) of thin portion thickness and have the manufacture method of taper plate more than 10mm.
For the method for dealing with problems
The inventor is in order to solve the problems of the technologies described above, Ti, N content are investigated to the different thick portion of the taper plate that contains B of Ti, N content and the impact of the intensity difference of thin portion, Ti, satisfied 0≤N-Ti/3.42≤0.0025 o'clock of N content are obtained, can stably guarantee the solid solution B (solid solute B) of appropriate amount, the opinion that the intensity difference of thick portion and thin portion reduces.
The present invention further studies and completes based on above-mentioned opinion, that is, the present invention is:
1. tensile strength is that 570MPa is above, thick portion thickness is a manufacture method for taper plate more than 10mm with the difference of thin portion thickness, wherein, and by after heating steel billet to 1000 DEG C～1200 DEG C, with 900 DEG C below and Ar 3the above finishing temperature of point is carried out thickness of slab and is varied to along its length the hot rolling of wedge-like, then, acceleration is cooled to below 500 DEG C, wherein, described steel billet is in quality % C:0.03～0.12%, Si:0.03～0.5%, Mn:0.8～2.2%, below P:0.015%, S:0.0005～0.0050%, Al:0.005～0.1%, Nb:0.003～0.014%, Ti:0.003～0.02%, B:0.0003～0.0025%, N:0.0030～0.0070%, Ca:0.0005～0.0050%, and meet (1) formula, surplus is made up of Fe and inevitable impurity,
0≤N-Ti/3.42≤0.0025····(1)
Wherein, the quality % content that N, Ti are each composition.
2. the tensile strength as described in 1 is that 570MPa is above, the difference of thick portion thickness and thin portion thickness is the manufacture method of taper plate more than 10mm, wherein, the one-tenth of described steel billet is grouped in quality % and also contains and be selected from one or more in Cu:0.05～1.0%, Ni:0.05～1.0%, Cr:0.05～0.5%, Mo:0.05～0.5%, V:0.02～0.1%.
3. the tensile strength as described in 1 or 2 is that 570MPa is above, the difference of thick portion thickness and thin portion thickness is the manufacture method of taper plate more than 10mm, wherein, the one-tenth of described steel billet is grouped in quality % and also contains and be selected from one or more in Mg:0.0005～0.005%, Zr:0.003～0.02%, REM:0.003～0.02%.
4. the tensile strength as described in any one in 1～3 is that 570MPa is above, the difference of thick portion thickness and thin portion thickness is the manufacture method of taper plate more than 10mm, it is characterized in that, the one-tenth of described steel billet is grouped in quality % and also contains below O:0.0030%, and each content of Ca, O, S meets following (2) formula
0.3≤ACR≤0.8·····(2)
Wherein, ACR=(Ca-(0.18+130 × Ca) × O)/1.25/S,
Ca, O, S represent the quality % content of each composition.
Invention effect
According to the present invention, can manufacture tensile strength and be that 570MPa is above, the intensity difference of thick portion, thin portion is few, also can be applicable to union-melt weld (submerged arc welding), electro-gas welding (electrogas arc welding), the contour input heat welding of electroslag welding (electroslag welding) purposes, thick portion thickness is taper plate more than 10mm with poor (tilt quantity) of thin portion thickness, industrially exceedingly useful.
Embodiment
In the present invention, predetermined component forms, creates conditions.In explanation, % is quality %.
[one-tenth is grouped into]
C：0.03～0.12％
C adds more than 0.03% in order to obtain the intensity necessary as structural steel (structural steel).On the other hand, add while exceeding 0.12%, the toughness (toughness) of welding heat affected zone (welded heataffected zone) is reduced, therefore, be made as 0.03%～0.12%.Be preferably 0.04～0.09%.
Si：0.03～0.5％
Si, in order to ensure deoxidation (deoxidation) and intensity, adds more than 0.03%.Add while exceeding 0.5%, the in the situation that of the welding of height input heat, on welding heat affected zone, generate island martensite body, make toughness variation, therefore, be made as below 0.5%.Be preferably below 0.4%.
Mn：0.8～2.2％
Mn, in order to ensure the intensity of mother metal, adds more than 0.8%.On the other hand, while exceeding 2.2%, make the toughness of weld part show variation, therefore, be made as 0.8～2.2%, more preferably 1.2～2.0%.
Below P:0.015%
P is inevitable impurity in the present invention, contain while exceeding 0.015%, input heat by height and be welded on heat affected zone generation island martensite body (island martensite, M-A constituent), toughness, particularly CTOD characteristic (crack tip opening displacementproperty) are reduced, therefore, be made as below 0.015%.Be preferably below 0.012%.
S：0.0005～0.0050％
S, owing to generating CaS, MnS, is made as more than 0.0005%.On the other hand, while exceeding 0.0050%, make the toughness drop of mother metal, therefore, be made as 0.0005～0.0050%.
Al：0.005～0.1％
Al, in order to make steel-deoxidizing, is made as more than 0.005%.On the other hand, while exceeding 0.1%, the toughness drop of mother metal, the toughness of welding metal (weld metal) also reduces, and therefore, is made as 0.005～0.1%, is preferably 0.01～0.06%.
Nb：0.003～0.014％
Nb is effective in order to ensure the intensity (strength of weldjoint) of intensity, toughness and the weld seam of mother metal, in order to obtain this effect, need to be more than 0.003%, if but exceed 0.014%, in the time carrying out the welding of height input heat, the toughness drop of welding heat affected zone, therefore, is made as 0.003～0.014%.Be preferably 0.005～0.013%.
Ti：0.003～0.02％
Ti generates TiN in the time solidifying, separate out, be suppressed at the coarsening of the austenite particle (austenite grain) of welding heat affected zone, become ferrite transformation core (nucleus of ferrite transformation), ferrite is separated out, improve toughness, therefore, add more than 0.003%.On the other hand, while exceeding 0.02%, the chap of TiN particle is large, makes toughness drop, therefore, is made as 0.003～0.02%.Be preferably 0.005～0.018%.
B：0.0003～0.0025％
When B manufactures at steel plate, form with solid solution B (solute B) contributes to hardenability (hardenability), and strength of parent is improved, and in the time carrying out the welding of height input heat, generate BN at welding heat affected zone, reduce solid solution N, in addition, form ferrite transformation core, generate ferrite, improve toughness, therefore, add more than 0.0003%.
On the other hand, while exceeding 0.0025%, hardenability increases, and toughness drop, therefore, is made as 0.0003～0.0025%.Be preferably 0.0005～0.0022%.
N：0.0030～0.0070％
N improves effective TiN in order to generate to toughness, is made as more than 0.0030%.On the other hand, if exceed 0.0070%, sometimes cannot guarantee to contribute to the solid solution B of hardenability in the time that steel plate is manufactured, and in the time carrying out the welding of height input heat, near TiN weld part (weld bond) melts, and the solid solution N in welding metal increases, and makes its toughness variation, therefore, be made as 0.0030～0.0070%.
0≤N-Ti/3.42≤0.0025
In the present invention, require tensile strength to be that 570MPa is above, strength variance is little and welding heat input exceedes the good-toughness of the height input heat weld part of 300kJ/cm, therefore, in mentioned component composition, specify this parameter type (formula).When Ti, N content reach N-Ti/3.42 > 0.0025, cannot stably guarantee the solid solution B of appropriate amount, for the variation of thickness of slab and rolling condition (rolling condition), the deviation of intensity increases.On the other hand, the in the situation that of N-Ti/3.42 < 0, in the time carrying out the welding of height input heat, the toughness of welding heat affected zone is showing variation.Therefore, be made as 0≤N-Ti/3.42≤0.0025.
Ca：0.0005～0.0050％
Ca makes the toughness of welding heat affected zone good in the time carrying out high input heat welding, and on CaS, MnS, TiN, BN separate out, and by improving ferritic caryogenic frequency, the toughness of welding heat affected zone is improved.In order to obtain this effect, be made as more than 0.0005%.On the other hand, while exceeding 0.0050%, effect is saturated, therefore, is made as 0.0005～0.0050%.Be preferably 0.0005～0.0030%, more preferably 0.0007～0.0030%.
Be more than basal component of the present invention, obtain sufficient action effect, but in the situation that further making characteristic improve, can contain one or more in Cu, Ni, Cr, Mo, V, Mg, Zr, REM.
Cu：0.05～1.0％
Cu is effective to the high strength of mother metal, in order to obtain this effect, preferably contains more than 0.05%, but while exceeding 1.0%, produce red brittleness (hot shortness), make the surface texture variation of steel plate, therefore,, containing sometimes, be preferably made as below 1.0%.More preferably 0.1～0.8%.
Ni：0.05～1.0％
When mother metal is kept high tenacity by Ni, intensity is raise, therefore, in order to obtain this effect, preferably contain more than 0.05%.On the other hand, while exceeding 1.0%, this effect is saturated, therefore, containing sometimes, is preferably made as 0.05～1.0%.More preferably 0.1～0.9%.
Cr：0.05～0.5％
Cr is effective to the high strength of mother metal, in order to obtain this effect, preferably contains more than 0.05%, but while adding in a large number, makes toughness variation, therefore, containing sometimes, is preferably made as below 0.5%.More preferably 0.1～0.4%.
Mo：0.05～0.5％
Mo is effective to the high strength of mother metal, in order to obtain this effect, preferably contains more than 0.05%, but while adding in a large number, makes toughness variation, therefore, containing sometimes, is preferably made as below 0.5%.More preferably 0.07～0.4%.
V：0.02～0.1％
V is effective to the high strength of mother metal, in order to obtain this effect, preferably contains more than 0.02%, but while exceeding 0.1%, makes toughness drop, therefore, containing sometimes, is preferably made as below 0.1%.More preferably 0.04～0.08%.
Mg：0.0005～0.005％
Mg is the element with the tough property improvement effect that the dispersion of oxide compound causes.In order to bring into play such effect, preferably contain more than at least 0.0005%, even but exceed and contain 0.005%, effect is also saturated, therefore, containing sometimes, is preferably made as below 0.005%.
Zr：0.003～0.02％
Zr is the element of the tough property improvement effect that causes of the dispersion (dispersion) with oxide compound (oxide).In order to bring into play such effect, preferably contain more than at least 0.003%, even but exceed and contain 0.02%, effect is also saturated, therefore, containing sometimes, is preferably made as below 0.02%.More preferably 0.004～0.018%.
REM：0.003～0.02％
REM is the element with the tough property improvement effect that the dispersion of oxide compound causes.In order to bring into play such effect, preferably contain more than at least 0.003%, even but exceed and contain 0.02%, effect is also saturated, therefore, containing sometimes, is preferably made as below 0.02%.More preferably 0.004～0.018%.
Below O:0.0030%
O contains as inevitable impurity, and the form with oxide compound in steel exists, and makes purity drop.Therefore,, in the present invention, preferably reduce as far as possible.When O content exceedes 0.0030%, CaO is that inclusion chap is large, and toughness is produced to detrimentally affect.In addition, in the present invention, make the form crystallization of Ca with CaS, therefore, degassed with O strengthening before Ca adds that the bonding force of Ca is strong, or drop into reductor, preferably the O in molten steel is reduced to below 0.0030%.
0.3≤ACR≤0.8
Wherein, ACR=(Ca-(0.18+130 × Ca) × O)/1.25/S
Ca, O, S represent the quality % content of each composition.
The ferrite transformation product nucleus that at high temperature also can not melt while welding in order to make height input heat disperses minutely, make the small ferrite of being organized as of welding heat affected zone+pearlitic tissue realize high tenacity, Ca and S need to contain in the mode of the relation that meets 0.3≤ACR≤0.8.
Be more than 0.3 and below 0.8 by making the value of ACR, the MnS working as ferrite product nucleus separates out on CaS, disperses minutely, therefore, welding heat affected zone can make high input heat welding time be organized as small ferrite+pearlitic tissue, realize high tenacity.
When the value less than 0.3 of ACR, CaS is not owing to there is no crystallization, and therefore, S separates out in the independent mode of MnS.Rolled elongated when this MnS manufactures by steel plate, causes the reduction of the toughness of mother metal, and because major objective of the present invention melts at welding heat affected zone MnS, therefore, can not realize small dispersion.
On the other hand, the value of ACR exceedes at 0.8 o'clock, and most S is fixed by Ca, and the MnS working as ferrite product nucleus can not separate out on CaS, therefore, can not bring into play sufficient function.
[creating conditions]
In the present invention, by forming mentioned component composition, the solid solution B of appropriate amount can be stably guaranteed, therefore, the deviation of intensity can be dwindled for the variation of thickness of slab and rolling condition.Therefore, in the past, adopt acceleration cooling during in order to make taper plate high strength, along with thickness of slab changes to thin portion from thick portion, armor plate strength is change inevitably, and result, in the present invention, even if adopt acceleration cooling, also can obtain the little high strength taper plate of intensity difference of thick portion and thin portion.
As the steel billet of the former material of taper plate of the present invention, the steel of mentioned component composition can carried out after melting by common smelting technologyes (refining process) such as such as converter (steel converter), electric furnace (electric furnace), vacuum melting furnaces (vacuum melting furnace), use the ordinary methods such as continuous metal cast process (continuous casting) or ingot casting-split rolling method method to manufacture, be not particularly limited.
In the present invention, specify as follows billet heating temperature (slab heating temperature), hot-rolled condition (hot rolling condition), cooling conditions (cooling condition).
Billet heating temperature: 1000～1200 DEG C
When billet heating temperature is less than 1000 DEG C, added ingredients is solid solution fully.On the other hand, while exceeding 1200 DEG C, the chap of austenite particle is large, even can not carry out little granulation, toughness variation by rolling afterwards.Therefore, billet heating temperature is made as the scope of 1000～1200 DEG C.Be preferably the scope of 1030～1180 DEG C.
Hot-rolled condition
By after heating steel billet, carry out hot rolling.Give the different tapering of thickness of slab in the longitudinal direction by hot rolling.By nipping after steel plate, in predefined passage, make roll opening (roll gap) change, carry out hot rolling, can realize thus the variation of the thickness of slab of the length direction in taper plate.
In the present invention, the amount of rolling (rolling reduction) (also referred to as rolling rate) to each passage (pass) is not particularly limited.The finishing temperature (finishing rolling temperature) of hot rolling is surface of steel plate temperature, is made as 900 DEG C of following and Ar 3more than point.Finishing temperature is less than Ar 3when point, can not obtain the intensity of regulation, in addition, while exceeding 900 DEG C, toughness variation, therefore, finishing temperature is made as 900 DEG C of following and Ar 3more than point.Be preferably (Ar 3+ 10 DEG C)～the scope of 880 DEG C.
Cooling conditions
After finishing, hot rolling accelerates cooling (accelerated cooling).Cooling when stopping temperature (cooling stop temperature) and exceeding 500 DEG C, can not obtain armor plate strength more than tensile strength 570MPa, therefore, at surface of steel plate temperature, accelerate to be cooled to below 500 DEG C.Be preferably 490 DEG C of following scopes.
It should be noted that the surface of steel plate temperature of regulation hot-rolled condition, cooling conditions can be used and for example radiate thermometer (radiation thermometer) and measure.
The present invention consists of and the combination of creating conditions mentioned component, can stably guarantee the solid solution B of appropriate amount, obtain the raising effect of the toughness of the raising effect of hardenability and the welding heat affected zone of high input heat welding, therefore, poor (tilt quantity) of the thick portion thickness of taper plate and thin portion thickness even if be more than 10mm in steel plate, and also obtaining tensile strength is the taper plate that 570MPa is above, have the toughness of the welding heat affected zone of good height input heat welding.
[embodiment 1]
The steel billet with the chemical constitution shown in table 1 (chemical composition) is carried out to hot rolling under the conditions shown in Table 2, manufacture the taper plate of the thick 60mm of portion, the thin 50mm of portion, tilt quantity (thick portion thickness and thin portion thickness poor) 10mm.
By thick portion and thin portion thickness of slab 1/4 position separately of taper plate, gather the pole tension test sheet (round bar type tensile specimen) of parallel portion 14 Φ × 85mm, punctuate spacing (gauge length) 70mm along the direction vertical with rolling direction (rolling direction), gather 2mmV breach Charpy test sheet (V notched charpy specimen) along the direction parallel with rolling direction, evaluate the absorption energy (absorbed energy) at the intensity of mother metal and-40 DEG C.Absorption energy at-40 DEG C is made as the mean value of 3 values.
In addition, (following in order to evaluate welding heat affected zone, also referred to as HAZ) toughness, the test film that gathers width 80mm × length 80mm × thickness 15mm from these steel plates is for Thermal Cycle (weld thermal cycle), about having applied being heated to after 1450 DEG C with 270 seconds the test film of Thermal Cycle of cooling 800～500 DEG C (suitable with the thermal cycling of the welding heat affected zone of the input heat 400kJ/cm in electro-gas welding in the steel plate of thickness of slab 55mm), implement 2mmV breach Charpy test, Simulation HAZ toughness (toughness of Simulated HAZ).
Toughness after the mechanical properties of the thick portion of taper plate, thin portion and Thermal Cycle is shown in to table 2.No.1～the No. of the inventive example all meets that YS:460MPa is above, TS:570MPa above, absorption energy at-40 DEG C: 300J above (3 times average), the intensity difference of thick portion, thin portion is all little, TS is less than 20MPa, YS is less than 30MPa, in addition, simulated HAZ toughness is also good, for below vTrs:-40 DEG C.
On the other hand, reach the intensity difference of the thick portion of No.11, the No.14 of N-Ti/3.42 > 0.0025, thin portion large.In addition, the example at suitable composition or outside creating conditions, more than obtaining meeting YS:460MPa, TS:570MPa is above, absorb that energy: 300J is above, vTrs:-40 DEG C of simulated HAZ toughness is with any one lower above result.
[embodiment 2]
The steel billet with the chemical constitution shown in table 3 is carried out to hot rolling under the conditions shown in Table 4, manufacture the taper plate of the thick 60mm of portion, the thin 50mm of portion, tilt quantity (thick portion thickness and thin portion thickness poor) 10mm.
By thick portion and thin portion thickness of slab 1/4 position separately of taper plate, gather the pole tension test sheet of parallel portion 14 Φ × 85mm, punctuate spacing 70mm along the direction vertical with rolling direction, gather 2mmV breach Charpy test sheet along the direction parallel with rolling direction, evaluate the absorption energy at the intensity of mother metal and-40 DEG C.Absorption energy at-40 DEG C is made as the mean value of 3 values.
In addition, (following in order to evaluate welding heat affected zone, also referred to as HAZ) toughness, the test film that gathers width 80mm × length 80mm × thickness 15mm from these steel plates is for Thermal Cycle, about having applied being heated to after 1450 DEG C with 270 seconds the test film of Thermal Cycle of cooling 800～500 DEG C (suitable with the thermal cycling of the welding heat affected zone of the input heat 400kJ/cm in electro-gas welding in the steel plate of thickness of slab 55mm), implement 2mmV breach Charpy test, Simulation HAZ toughness.
Toughness after the mechanical properties of the thick portion of taper plate, thin portion and Thermal Cycle is shown in to table 4.Meet that the No.21 of the inventive example of the regulation of ACR and No.22 all meet that YS:460MPa is above, TS:570MPa is above, absorption energy at-40 DEG C: 300J above (3 average), the intensity difference of thick portion, thin portion is all little, TS is less than 20MPa, YS is less than 30MPa, in addition, simulated HAZ toughness is also good, for below vTrs:-65 DEG C.
Table 1-1
(quality %)
Steel No. C Si Mn P S Al Cu Ni Cr Mo V Nb Ti Ca Distinguish
1 0.055 0.06 2.05 0.005 0.0022 0.048 - - - - - 0.013 0.017 0.0022 Example
2 0.100 0.25 1.53 0.011 0.0019 0.032 - - - - - 0.012 0.013 0.0025 Example
3 0.058 0.07 1.55 0.006 0.0018 0.053 0.33 0.77 - - - 0.014 0.014 0.0018 Example
4 0.051 0.17 1.82 0.004 0.0019 0.036 - - 0.12 - - 0.010 0.013 0.0018 Example
5 0.049 0.10 1.98 0.005 0.0021 0.055 - - 0.20 - - 0.011 0.011 0.0017 Example
6 0.045 0.07 1.85 0.008 0.0010 0.042 - - - 0.2 - 0.012 0.014 0.0031 Example
7 0.042 0.12 1.52 0.006 0.0021 0.036 0.45 0.78 - - 0.04 0.007 0.011 0.0016 Example
8 0.072 0.08 1.56 0.007 0.0035 0.055 0.38 0.87 - - - 0.008 0.008 0.0021 Example
9 0.170 0.07 1.82 0.006 0.0023 0.042 - - - - - 0.012 0.013 0.0015 Comparative example
10 0.045 0.09 2.52 0.004 0.0019 0.032 - - - - - 0.012 0.011 0.0020 Comparative example
11 0.052 0.06 1.57 0.008 0.0024 0.052 0.65 0.66 - - - 0.010 0.009 0.0015 Comparative example
12 0.075 0.11 1.86 0.014 0.0022 0.044 - - - - - 0.008 0.012 0.0019 Comparative example
13 0.052 0.07 1.78 0.006 0.0014 0.037 - - - 0.3 - 0.011 0.008 0.0018 Comparative example
14 0.056 0.10 2.08 0.005 0.0022 0.048 - - - - - 0.010 0.013 0.0017 Comparative example
15 0.049 0.08 1.96 0.005 0.0022 0.051 - - - - - 0.012 0.012 0.0001 Comparative example
16 0.055 0.08 1.57 0.007 0.0021 0.047 0.35 0.75 - - - 0.018 0.011 0.0018 Comparative example
Note 1 underscore is outside the scope of the invention
Wherein, each symbol of element represents quality % content to note 2 Ceq (IIW)=C+Mn/6+ (Cr+Mo+V)/5+ (Cu+Ni)/15 (%).
Note 3 Ar 3(DEG C)=910-273C-74Mn-57Ni-16Cr-9Mo-5Cu wherein, each symbol of element represents quality % content.
Note 4 (1) formulas: wherein, N, Ti represent the quality % content of each composition in 0≤N-Ti/3.42≤0.0025.
Table 1-2
Steel No. Mg Zr REM B N Ceq(IIW) (1) formula Ar 3 Distinguish
1 - - - 0.0008 0.0052 0.397 0.0002 743 Example
2 - - - 0.0011 0.0042 0.355 0.0004 769 Example
3 - - - 0.0012 0.0046 0.390 0.0005 734 Example
4 - - - 0.0014 0.0052 0.378 0.0014 759 Example
5 0.0011 - - 0.0017 0.0035 0.419 0.0003 747 Example
6 - - - 0.0021 0.0063 0.393 0.0022 759 Example
7 - 0.0090 - 0.0012 0.0045 0.385 0.0013 739 Example
8 - - 0.0070 0.0011 0.0042 0.415 0.0019 723 Example
9 - - - 0.0013 0.0048 0.473 0.0010 729 Comparative example
10 - - - 0.0015 0.0042 0.465 0.0010 711 Comparative example
11 - - - 0.0011 0.0057 0.401 0.0031 739 Comparative example
12 - - - 0.0000 0.0052 0.385 0.0017 752 Comparative example
13 - - 0.0080 0.0014 0.0022 0.409 -0.0001 761 Comparative example
14 0.0012 - - 0.0012 0.0075 0.403 0.0037 741 Comparative example
15 - - - 0.0013 0.0050 0.376 0.0015 752 Comparative example
16 - - - 0.0011 0.0045 0.390 0.0013 734 Comparative example
Note 1 underscore is outside the scope of the invention
Wherein, each symbol of element represents quality % content to note 2 Ceq (IIW)=C+Mn/6+ (Cr+Mo+V)/5+ (Cu+Ni)/15 (%).
Note 3 Ar 3(DEG C)=910-273C-74Mn-57Ni-16Cr-9Mo-5Cu wherein, each symbol of element represents quality % content.
Note 4 (1) formulas: wherein, N, Ti represent the quality % content of each composition in 0≤N-Ti/3.42≤0.0025.
Table 2
Note 1 underscore is outside the scope of the invention
Table 3
Steel No. C Si Mn P S Al Cu Ni Cr Mo V Nb Ti Ca Mg
21 0.047 0.06 1.93 0.005 0.0016 0.039 0.08 0.33 - - - 0.012 0.014 0.0022 -
22 0.053 0.05 1.57 0.004 0.0021 0.042 0.32 0.74 - 0.05 - 0.009 0.015 0.0019 -
(quality %)
Steel No. Zr REM B N O Ceq(IIW) (1) formula ACR Ar 3 Distinguish
21 - - 0.0021 0.0063 0.0019 0.396 0.0022 0.657 735 Example
22 - - 0.0012 0.0045 0.0025 0.395 0.0001 0.317 735 Example
Wherein, each symbol of element represents quality % content to note 1 Ceq (IIW)=C+Mn/6+ (Cr+Mo+V)/5+ (Cu+Ni)/15 (%).
Note 2 Ar 3(DEG C)=910-273C-74Mn-57Ni-16Cr-9Mo-5Cu wherein, each symbol of element represents quality % content.
Note 3 (1) formulas: wherein, N, Ti represent the quality % content of each composition in 0≤N-Ti/3.42≤0.0025.
Wherein, Ca, O, S represent the quality % content of each composition to note 4 ACR=(Ca-(0.18+130 × Ca) × 0)/1.25/S.
Table 4

Claims (4)

1. tensile strength is that 570MPa is above, thick portion thickness is a manufacture method for taper plate more than 10mm with the difference of thin portion thickness, wherein, and by after heating steel billet to 1000 DEG C～1200 DEG C, with 900 DEG C below and Ar 3the above finishing temperature of point is carried out thickness of slab and is varied to along its length the hot rolling of wedge-like, then, acceleration is cooled to below 500 DEG C, wherein, described steel billet is in quality % C:0.03～0.12%, Si:0.03～0.5%, Mn:0.8～2.2%, below P:0.015%, S:0.0005～0.0050%, Al:0.005～0.1%, Nb:0.003～0.014%, Ti:0.003～0.02%, B:0.0003～0.0025%, N:0.0030～0.0070%, Ca:0.0005～0.0050%, and meet (1) formula, surplus is made up of Fe and inevitable impurity,
0≤N-Ti/3.42≤0.0025····(1)
Wherein, the quality % content that N, Ti are each composition.
2. tensile strength as claimed in claim 1 is that 570MPa is above, the difference of thick portion thickness and thin portion thickness is the manufacture method of taper plate more than 10mm, wherein, the one-tenth of described steel billet is grouped in quality % and also contains and be selected from one or more in Cu:0.05～1.0%, Ni:0.05～1.0%, Cr:0.05～0.5%, Mo:0.05～0.5%, V:0.02～0.1%.
3. tensile strength as claimed in claim 1 or 2 is that 570MPa is above, the difference of thick portion thickness and thin portion thickness is the manufacture method of taper plate more than 10mm, wherein, the one-tenth of described steel billet is grouped in quality % and also contains and be selected from one or more in Mg:0.0005～0.005%, Zr:0.003～0.02%, REM:0.003～0.02%.
4. the tensile strength as described in any one in claim 1～3 is that 570MPa is above, the difference of thick portion thickness and thin portion thickness is the manufacture method of taper plate more than 10mm, it is characterized in that, the one-tenth of described steel billet is grouped in quality % and also contains below O:0.0030%, and each content of Ca, O, S meets following (2) formula
0.3≤ACR≤0.8·····(2)
Wherein, ACR=(Ca-(0.18+130 × Ca) × O)/1.25/S,
Ca, O, S represent the quality % content of each composition.
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CN108396222A (en) * 2017-02-08 2018-08-14 鞍钢股份有限公司 A kind of 235MPa grades of LP steel plate and its production method
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