CN104066858B - The manufacture method of taper plate - Google Patents

The manufacture method of taper plate Download PDF

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Publication number
CN104066858B
CN104066858B CN201280067544.9A CN201280067544A CN104066858B CN 104066858 B CN104066858 B CN 104066858B CN 201280067544 A CN201280067544 A CN 201280067544A CN 104066858 B CN104066858 B CN 104066858B
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thickness
thick portion
taper plate
thin section
toughness
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CN104066858A (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 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

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

Welding heat input is provided to input that heat welding can be suitable for, that tensile strength is the taper plate of more than 570MPa manufacture method more than the height of 300kJ/cm.Specifically, by after heating steel billet to 1000 DEG C ~ 1200 DEG C, with less than 900 DEG C and Ar 3the above finishing temperature of point carries out the hot rolling that thickness of slab is changing into wedge-like along its length, then, below accelerating cooling to 500 DEG C, wherein, described steel billet C:0.03 ~ 0.12% in mass %, 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 wherein, N, Ti is the quality % content (1) of each composition.

Description

The manufacture method of taper plate
Technical field
The present invention relates to and be suitable for shipbuilding (shipbuilding), building (architecture) etc., thickness of slab along its length continually varying taper plate (taperedplate) (also referred to as wedge-like steel plate (taperedsteelplates), LP steel plate (LongitudinallyProfiledSteelPlate)) manufacture method, the intensity difference related in steel plate is few, and welding heat input (weldingheatinput) can be suitable for more than height input heat welding (high-heatinputwelding) of 300kJ/cm, tensile strength (tensilestrength) is more than 570MPa, and there is the manufacture method of the taper plate of the thick portion thickness of more than 10mm and the difference (thickness of slab difference (differenceofsteelplatethickness)) of thin section thickness in the longitudinal direction.
Background technology
The shape of Plate Steel is all uniform usually on width and length direction.But, make thickness of slab along its length consecutive variations time, sometimes to the reduction of (weldingman-hour) when the alleviating of former material weight (materialweight), Welder, there is 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 manufacture taper plate as object using high dimensional accuracy (dimensionalaccuracy).But, except dimensional precision, if the homogeneity (materialuniformity) of the material characteristic (materialproperty) of steel plate and material can not meet, then can not tolerate practical application.
Recently, become strict to the quality requirements (qualitydemand) of Plate Steel, particularly the requirement of high strength and the raising of weldability (weldability) require to smarten.For such requirement, adopt controlled rolling (controlledrolling) and the such TMCP method (Thermo-MechanicalControlProcess, thermomechanical Controlling Technology) of controlled cooling model (controlledcooling).The method is by forcing work (heavyreduction) and the austenite → ferrite transformation (ferritetransformation) after it in austenite non-recrystallization region (no-recrystallizationtemperaturerangeinaustenite) or (austenite+ferrite (ferrite)) two phase regions, realize the microminiaturization of ferrite crystal grain (ferriticgrain), and then cool as required, realize high strength, high tenacity further.
But when the method is applied to taper plate, temperature treatment (temperaturecontrol) is extremely difficult, material variation (variationofmaterialproperty) increases.
Particularly controlled rolling be under the region rolling of austenite non-recrystallization and the such low temperature of (austenite+ferrite) two phase region rollings (dualphaserolling, dual-phaserolling) force work when, when as taper plate, on thickness of slab direction, thickness is different, the temperature head of the steel billet temperature in thin section and thick portion becomes excessive, the problem that the difference that there is intensity increases.In order to eliminate uneven (inhomogeneousofmaterial) of such material, manufacture the taper plate of homogeneous, having carried out some motions.
Such as, Patent Document 4 discloses a kind of method of cooling of taper plate, it is in order to obtain uniform material, the distribution of the temperature of the length direction before actual measurement cooling, based on this measured value, the Investigation of Optimum Cooling Condition (optimumcoolingcondition) of computing each point, the plate speed (conveyingspeed) when cooling according to thickness of slab correction.Patent Document 5 discloses and begin to cool down simultaneously in the thin section of steel plate and thick portion and change the method for cooling of the taper plate in the period occurring refrigerating unit, or cooling starts successively along steel plate length direction and terminates the method for cooling of the taper plate cooled simultaneously.All the motions of the deviation (variationofmaterialproperty) reducing the material in steel plate when carrying out accelerating cooling.
On the other hand, be grouped into the example attempting solving such technical problem as the one-tenth by designing steel plate, there is patent documentation 6.Disclose in this technology by Nb addition is risen to 0.015% ~ 0.06%, the deviation (scatterofstrength) of intensity is reduced.
In addition, make by Hv if Patent Document 7 discloses 20-50the Hv that=-110+460C+44Si+39Mn-31Cu-9Ni+11Cr+22Mo+180V+9600B-23000Mo × B represents 20-50value (difference of Hv hardness when being cooled to normal temperature with the speed of cooling suitable with the cooling rate (aircooling) at 800 ~ 500 DEG C of the thickness of slab steel plate that is 20mm and 50mm) for less than 15, then makes the deviation of intensity reduce.
But, in recent years, in the steel that height input heat welding (high-heatinputwelding) increased in its demand can be suitable for, in order to ensure the toughness of weld part, there is restriction in various Composition Design (alloydesign), therefore, as taper plate, be not easy from the Composition Design of the viewpoint reducing strength variance, particularly when the steel of the height input heat welding containing B, exist and become according to thickness of slab and the change of finishing temperature (finishingtemperature), the deviation tendency of intensity the problem shown.
Prior art document
Patent documentation
Patent documentation 1: Japanese Patent Publication 50-36826 publication
Patent documentation 2: Japanese Patent Publication 60-124 publication
Patent documentation 3: Japanese Patent Publication 5-49361 publication
Patent documentation 4: Japanese Laid-Open Patent Publication 62-166013 publication
Patent documentation 5: Japanese Unexamined Patent Publication 7-68309 publication
Patent documentation 6: Japanese Patent No. 3180944 publication
Patent documentation 7: Japanese Patent No. 3972553 publication
Summary of the invention
The problem that invention will solve
The object of the invention is to, advantageously solve the problem, provide that tensile strength (tensilestrength) is more than 570MPa, the deviation of intensity is little and welding heat input (weldingheatinput) more than the weld part of the height input heat of 300kJ/cm good-toughness, the thick portion thickness of length direction and the difference (tilt quantity) of thin section thickness have the manufacture method of the taper plate of more than 10mm.
For the method for dealing with problems
The present inventor is in order to solve the problems of the technologies described above, investigated Ti, N content on Ti, N content different containing the thick portion of taper plate of B and the impact of the intensity difference of thin section, obtain Ti, N content meet 0≤N-Ti/3.42≤0.0025 time, stably can guarantee the solid solution B (solidsoluteB) of appropriate amount, the opinion that the intensity difference of thick portion and thin section reduces.
The present invention carries out further studying based on above-mentioned opinion and completes, that is, the present invention is:
1. tensile strength is more than 570MPa, the difference of thick portion thickness and thin section thickness is a manufacture method for the taper plate of more than 10mm, wherein, by after heating steel billet to 1000 DEG C ~ 1200 DEG C, with less than 900 DEG C and Ar 3the above finishing temperature of point carries out the hot rolling that thickness of slab is changing into wedge-like along its length, then, below accelerating cooling to 500 DEG C, wherein, described steel billet C:0.03 ~ 0.12% in mass %, 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, N, Ti are the quality % content of each composition.
2. the tensile strength as described in 1 is more than 570MPa, the difference of thick portion thickness and thin section thickness is the manufacture method of the taper plate of more than 10mm, wherein, the one-tenth of described steel billet be grouped in mass % also containing be selected from 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% one or more.
3. the tensile strength as described in 1 or 2 is more than 570MPa, the difference of thick portion thickness and thin section thickness is the manufacture method of the taper plate of more than 10mm, wherein, the one-tenth of described steel billet be grouped in mass % also containing be selected from Mg:0.0005 ~ 0.005%, Zr:0.003 ~ 0.02%, REM:0.003 ~ 0.02% one or more.
4. as tensile strength according to any one of 1 ~ 3 be more than 570MPa, the difference of thick portion thickness and thin section thickness is the manufacture method of the taper plate of more than 10mm, it is characterized in that, the one-tenth of described steel billet is grouped in mass % also containing 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 that tensile strength is more than 570MPa, thick portion, thin section intensity difference few, also can be applicable to union-melt weld (submergedarcwelding), electro-gas welding (electrogasarcwelding), electroslag welding (electroslagwelding) contour input heat welding purposes, taper plate that the difference (tilt quantity) of thick portion thickness and thin section thickness is more than 10mm, industrially exceedingly useful.
Embodiment
In the present invention, predetermined component composition, manufacturing condition.In explanation, % is quality %.
[one-tenth is grouped into]
C：0.03～0.12％
C adds more than 0.03% to obtain as the necessary intensity of structural steel (structuralsteel).On the other hand, when adding more than 0.12%, the toughness (toughness) of welding heat affected zone (weldedheataffectedzone) is reduced, therefore, is set to 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%.When adding more than 0.5%, when height input heat welding, welding heat affected zone generates island-like martensite, makes degraded toughness, therefore, be set to less than 0.5%.Be preferably less than 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, during more than 2.2%, the toughness of weld part is shown and is deteriorated, therefore, be set to 0.8 ~ 2.2%, be more preferably 1.2 ~ 2.0%.
Below P:0.015%
P is inevitable impurity in the present invention, containing during more than 0.015%, be welded on heat affected zone by height input heat and generate island-like martensite (islandmartensite, M-Aconstituent), toughness, particularly CTOD characteristic (cracktipopeningdisplacementproperty) are reduced, therefore, less than 0.015% is set to.Be preferably less than 0.012%.
S：0.0005～0.0050％
S, owing to generating CaS, MnS, is set to more than 0.0005%.On the other hand, during more than 0.0050%, the toughness of mother metal is reduced, therefore, is set to 0.0005 ~ 0.0050%.
Al：0.005～0.1％
Al, in order to make steel-deoxidizing, is set to more than 0.005%.On the other hand, during more than 0.1%, the toughness of mother metal reduces, and the toughness of welding metal (weldmetal) also reduces, and therefore, is set to 0.005 ~ 0.1%, is preferably 0.01 ~ 0.06%.
Nb：0.003～0.014％
Nb is effective in order to ensure the intensity (strengthofweldjoint) of the intensity of mother metal, toughness and weld seam, in order to obtain this effect, need to be more than 0.003%, if but more than 0.014%, then when carrying out height input heat welding, the toughness of welding heat affected zone reduces, and therefore, is set to 0.003 ~ 0.014%.Be preferably 0.005 ~ 0.013%.
Ti：0.003～0.02％
Ti generates TiN when solidifying, separate out, suppress the coarsening at the austenite grain (austenitegrain) of welding heat affected zone, become ferrite transformation core (nucleusofferritetransformation), ferrite is separated out, improve toughness, therefore, add more than 0.003%.On the other hand, during more than 0.02%, TiN particle is greatly thicker, and toughness is reduced, and therefore, is set to 0.003 ~ 0.02%.Be preferably 0.005 ~ 0.018%.
B：0.0003～0.0025％
B is when steel plate manufactures, contribute to hardenability (hardenability) with the form of solid solution B (soluteB), strength of parent is improved, and when carrying out height input heat welding, BN is generated 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, during more than 0.0025%, hardenability increases, and toughness reduces, and therefore, is set to 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 set to more than 0.0030%.On the other hand, if more than 0.0070%, then sometimes cannot guarantee the solid solution B contributing to hardenability when steel plate manufactures, and when carrying out height input heat welding, TiN near weld part (weldbond) melts, and the solid solution N in welding metal increases, and makes its degraded toughness, therefore, 0.0030 ~ 0.0070% is set to.
0≤N-Ti/3.42≤0.0025
In the present invention, require that tensile strength is more than 570MPa, strength variance is little and welding heat input inputs the good-toughness of heat weld part more than the height of 300kJ/cm, therefore, in mentioned component composition, specify this parameter type (formula).When Ti, N content reach N-Ti/3.42 > 0.0025, stably cannot guarantee the solid solution B of appropriate amount, for the change of thickness of slab and rolling condition (rollingcondition), the deviation of intensity increases.On the other hand, when N-Ti/3.42 < 0, when carrying out height input heat welding, the toughness of welding heat affected zone shows and is deteriorated.Therefore, 0≤N-Ti/3.42≤0.0025 is set to.
Ca：0.0005～0.0050％
Ca makes the toughness of welding heat affected zone good when 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 are improved.In order to obtain this effect, be set to more than 0.0005%.On the other hand, during more than 0.0050%, effect is saturated, therefore, is set to 0.0005 ~ 0.0050%.Be preferably 0.0005 ~ 0.0030%, be more preferably 0.0007 ~ 0.0030%.
Be more than basal component of the present invention, obtain sufficient action effect, but when making characteristic improve further, can containing 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 containing more than 0.05%, but during more than 1.0%, producing red brittleness (hotshortness), the surface texture of steel plate is deteriorated, and therefore, containing sometimes, is preferably set to less than 1.0%.Be more preferably 0.1 ~ 0.8%.
Ni：0.05～1.0％
While mother metal is kept high tenacity by Ni, intensity is raised, therefore, in order to obtain this effect, preferably containing more than 0.05%.On the other hand, during more than 1.0%, this effect is saturated, therefore, containing sometimes, is preferably set to 0.05 ~ 1.0%.Be 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 containing more than 0.05%, but when adding in a large number, makes degraded toughness, therefore, containing sometimes, is preferably set to less than 0.5%.Be 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 containing more than 0.05%, but when adding in a large number, makes degraded toughness, therefore, containing sometimes, is preferably set to less than 0.5%.Be 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 containing more than 0.02%, but during more than 0.1%, toughness is reduced, and therefore, containing sometimes, is preferably set to less than 0.1%.Be more preferably 0.04 ~ 0.08%.
Mg：0.0005～0.005％
Mg is the element that toughness that the dispersion with oxide compound causes improves effect.In order to play such effect, preferably containing more than at least 0.0005%, even if but exceed containing 0.005%, effect is also saturated, therefore, containing sometimes, is preferably set to less than 0.005%.
Zr：0.003～0.02％
Zr is the element that toughness that the dispersion (dispersion) with oxide compound (oxide) causes improves effect.In order to play such effect, preferably containing more than at least 0.003%, even if but exceed containing 0.02%, effect is also saturated, therefore, containing sometimes, is preferably set to less than 0.02%.Be more preferably 0.004 ~ 0.018%.
REM：0.003～0.02％
REM is the element that toughness that the dispersion with oxide compound causes improves effect.In order to play such effect, preferably containing more than at least 0.003%, even if but exceed containing 0.02%, effect is also saturated, therefore, containing sometimes, is preferably set to less than 0.02%.Be more preferably 0.004 ~ 0.018%.
Below O:0.0030%
O contains as inevitable impurity, exists in the form of the oxide in steel, makes purity drop.Therefore, in the present invention, preferably reduce as far as possible.When O content is more than 0.0030%, CaO system inclusion is greatly thicker, produces detrimentally affect to toughness.In addition, in the present invention, make Ca with the form crystallization of CaS, therefore, the O strong with the bonding force of Ca strengthens degassed before Ca adds, or drops into reductor, preferably the O in molten steel is reduced to less than 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.
In order to the ferrite transformation product nucleus that at high temperature also can not melt when can make high input heat welding disperses minutely, make the small ferrite+pearlitic tissue that is organized as of welding heat affected zone realize high tenacity, Ca and S needs to contain in the mode of the relation meeting 0.3≤ACR≤0.8.
Be more than 0.3 by making the value of ACR and less than 0.8, the MnS worked as ferrite product nucleus separates out on CaS, disperses minutely, therefore, welding heat affected zone when can make high input heat welding be organized as small ferrite+pearlitic tissue, realize high tenacity.
When the value of ACR is less than 0.3, CaS is not owing to having crystallization, and therefore, S separates out in the mode that MnS is independent.Rolled elongated when this MnS is manufactured by steel plate, causes the reduction of the toughness of mother metal, and namely melts at welding heat affected zone MnS due to major objective of the present invention, therefore, can not realize small dispersion.
On the other hand, when the value of ACR is more than 0.8, most S is fixed by Ca, and the MnS worked as ferrite product nucleus can not separate out on CaS, therefore, can not play sufficient function.
[manufacturing condition]
In the present invention, by forming mentioned component composition, stably can guarantee the solid solution B of appropriate amount, therefore, the deviation of intensity can be reduced for the change of thickness of slab and rolling condition.Therefore, in the past, when adopting accelerating cooling to make taper plate high strength, along with thickness of slab changes from thick portion to thin section, armor plate strength is change inevitably, result, in the present invention, even if employing accelerating cooling, the high strength taper plate that the intensity difference of thick portion and thin section is little also can be obtained.
As the steel billet of the former material of taper plate of the present invention, can after the steel formed by mentioned component carries out melting by common smelting technologyes (refiningprocess) such as such as converter (steelconverter), electric furnace (electricfurnace), vacuum melting furnaces (vacuummeltingfurnace), use the ordinary methods such as continuous metal cast process (continuouscasting) or ingot casting-split rolling method method to manufacture, be not particularly limited.
In the present invention, specify billet heating temperature (slabheatingtemperature), hot-rolled condition (hotrollingcondition), cooling conditions (coolingcondition) as follows.
Billet heating temperature: 1000 ~ 1200 DEG C
When billet heating temperature is less than 1000 DEG C, added ingredients can not solid solution fully.On the other hand, during more than 1200 DEG C, austenite grain is greatly thicker, even if can not carry out granulation by rolling afterwards, and degraded toughness.Therefore, billet heating temperature is set to the scope of 1000 ~ 1200 DEG C.Be preferably the scope of 1030 ~ 1180 DEG C.
Hot-rolled condition
After heating steel billet, carry out hot rolling.Give thickness of slab in the longitudinal direction different taperings by hot rolling.After steel plate of nipping, in the passage preset, make roll opening (rollgap) change, carry out hot rolling, the change of the thickness of slab of the length direction in taper plate can be realized thus.
In the present invention, the amount of rolling (rollingreduction) (also referred to as rolling rate) of each passage (pass) is not particularly limited.The finishing temperature (finishingrollingtemperature) of hot rolling is surface of steel plate temperature, is set to less than 900 DEG C and Ar 3more than point.Finishing temperature is less than Ar 3during point, can not obtain the intensity specified, in addition, during more than 900 DEG C, degraded toughness, therefore, finishing temperature is set to less than 900 DEG C and Ar 3more than point.Be preferably (Ar 3+ 10 DEG C) ~ the scope of 880 DEG C.
Cooling conditions
Accelerating cooling (acceleratedcooling) is carried out after hot rolling terminates.When cooling stops temperature (coolingstoptemperature) more than 500 DEG C, the armor plate strength of more than tensile strength 570MPa can not be obtained, therefore, at surface of steel plate temperature, carry out below accelerating cooling to 500 DEG C.Be preferably the scope of less than 490 DEG C.
It should be noted that, the surface of steel plate temperature of regulation hot-rolled condition, cooling conditions, can use and such as radiate thermometer (radiationthermometer) and measure.
The present invention is by the combination of mentioned component composition with manufacturing condition, stably can 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, the thick portion thickness of taper plate and the difference (tilt quantity) of thin section thickness, even if be more than 10mm in steel plate, also obtain tensile strength and are more than 570MPa, have the taper plate that excellent height inputs the toughness of the welding heat affected zone of heat welding.
[embodiment 1]
The steel billet of the chemical constitution (chemicalcomposition) had shown in table 1 is carried out hot rolling under the conditions shown in Table 2, manufactures the taper plate of thick portion 60mm, thin section 50mm, tilt quantity (difference of thick portion thickness and thin section thickness) 10mm.
By thick portion and thin section thickness of slab 1/4 position separately of taper plate, the pole tension test sheet (roundbartypetensilespecimen) of parallel portion 14 Φ × 85mm, punctuate spacing (gaugelength) 70mm is gathered along the direction vertical with rolling direction (rollingdirection), gather 2mmV breach Charpy test sheet (Vnotchedcharpyspecimen) along the direction parallel with rolling direction, evaluate the intensity of mother metal and the absorption energy (absorbedenergy) at-40 DEG C.Absorption energy at-40 DEG C is set to 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 gathering width 80mm × length 80mm × thickness 15mm from these steel plates is used for Thermal Cycle (weldthermalcycle), about being applied with after being heated to 1450 DEG C with the test film of the Thermal Cycle of cooling in 270 seconds 800 ~ 500 DEG C (suitable with the thermal cycling of the welding heat affected zone of the input heat 400kJ/cm in the electro-gas welding in the steel plate of thickness of slab 55mm), implement 2mmV breach Charpy test, Simulation HAZ toughness (toughnessofSimulatedHAZ).
Toughness after the thick portion of taper plate, the mechanical properties of thin section and Thermal Cycle is shown in table 2.No.1 ~ the No. of example of the present invention all meets more than YS:460MPa, more than TS:570MPa, absorption energy at-40 DEG C: more than 300J (3 times average), the intensity difference of thick portion, thin section is all little, TS is less than 20MPa, YS is less than 30MPa, in addition, simulated HAZ toughness is also excellent, is less than vTrs:-40 DEG C.
On the other hand, reach the thick portion of No.11, No.14 of N-Ti/3.42 > 0.0025, thin section intensity difference large.In addition, the example outside suitable composition or manufacturing condition, obtains meeting more than YS:460MPa, any one the above result in more than TS:570MPa, absorption less than energy: more than 300J, simulated HAZ toughness vTrs:-40 DEG C.
[embodiment 2]
The steel billet with the chemical constitution shown in table 3 is carried out hot rolling under the conditions shown in Table 4, manufactures the taper plate of thick portion 60mm, thin section 50mm, tilt quantity (difference of thick portion thickness and thin section thickness) 10mm.
By thick portion and thin section thickness of slab 1/4 position separately of taper plate, the pole tension test sheet of parallel portion 14 Φ × 85mm, punctuate spacing 70mm is gathered along the direction vertical with rolling direction, gather 2mmV breach Charpy test sheet along the direction parallel with rolling direction, evaluate the intensity of mother metal and the absorption energy at-40 DEG C.Absorption energy at-40 DEG C is set to 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 gathering width 80mm × length 80mm × thickness 15mm from these steel plates is used for Thermal Cycle, about being applied with after being heated to 1450 DEG C with the test film of the Thermal Cycle of cooling in 270 seconds 800 ~ 500 DEG C (suitable with the thermal cycling of the welding heat affected zone of the input heat 400kJ/cm in the electro-gas welding in the steel plate of thickness of slab 55mm), implement 2mmV breach Charpy test, Simulation HAZ toughness.
Toughness after the thick portion of taper plate, the mechanical properties of thin section and Thermal Cycle is shown in table 4.No.21 and No.22 meeting the example of the present invention of the regulation of ACR all meets more than YS:460MPa, more than TS:570MPa, absorption energy at-40 DEG C: more than 300J (3 average), the intensity difference of thick portion, thin section is all little, TS is less than 20MPa, YS is less than 30MPa, in addition, simulated HAZ toughness is also excellent, is less than 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 2Ceq (IIW)=C+Mn/6+ (Cr+Mo+V)/5+ (Cu+Ni)/15 (%).
Note 3Ar 3wherein, each symbol of element represents quality % content to (DEG C)=910-273C-74Mn-57Ni-16Cr-9Mo-5Cu.
Note 4 (1) formula: 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 2Ceq (IIW)=C+Mn/6+ (Cr+Mo+V)/5+ (Cu+Ni)/15 (%).
Note 3Ar 3wherein, each symbol of element represents quality % content to (DEG C)=910-273C-74Mn-57Ni-16Cr-9Mo-5Cu.
Note 4 (1) formula: 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 1Ceq (IIW)=C+Mn/6+ (Cr+Mo+V)/5+ (Cu+Ni)/15 (%).
Note 2Ar 3wherein, each symbol of element represents quality % content to (DEG C)=910-273C-74Mn-57Ni-16Cr-9Mo-5Cu.
Note 3 (1) formula: 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 4ACR=(Ca-(0.18+130 × Ca) × 0)/1.25/S.
Table 4

Claims (5)

1. tensile strength is more than 570MPa, the difference of thick portion thickness and thin section thickness is a manufacture method for the taper plate of more than 10mm, wherein, by after heating steel billet to 1000 DEG C ~ 1200 DEG C, with less than 900 DEG C and Ar 3the above finishing temperature of point carries out the hot rolling that thickness of slab is changing into wedge-like along its length, then, below accelerating cooling to 500 DEG C, wherein, described steel billet C:0.03 ~ 0.12% in mass %, 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, N, Ti are the quality % content of each composition.
2. tensile strength as claimed in claim 1 is more than 570MPa, the difference of thick portion thickness and thin section thickness is the manufacture method of the taper plate of more than 10mm, wherein, the one-tenth of described steel billet be grouped in mass % also containing be selected from 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% one or more.
3. tensile strength as claimed in claim 1 or 2 is more than 570MPa, the difference of thick portion thickness and thin section thickness is the manufacture method of the taper plate of more than 10mm, wherein, the one-tenth of described steel billet be grouped in mass % also containing be selected from Mg:0.0005 ~ 0.005%, Zr:0.003 ~ 0.02%, REM:0.003 ~ 0.02% one or more.
4. tensile strength as claimed in claim 1 or 2 is more than 570MPa, the difference of thick portion thickness and thin section thickness is the manufacture method of the taper plate of more than 10mm, it is characterized in that, the one-tenth of described steel billet is grouped in mass % also containing 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.
5. tensile strength as claimed in claim 3 is more than 570MPa, the difference of thick portion thickness and thin section thickness is the manufacture method of the taper plate of more than 10mm, it is characterized in that, the one-tenth of described steel billet is grouped in mass % also containing 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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