CN103249847A - Method for manufacturing high-strength cold-rolled/hot-rolled trip steel having a tensile strength of 590 mpa grade, superior workability, and low mechanical-property deviation - Google Patents
Method for manufacturing high-strength cold-rolled/hot-rolled trip steel having a tensile strength of 590 mpa grade, superior workability, and low mechanical-property deviation Download PDFInfo
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- 229910000831 Steel Inorganic materials 0.000 title claims description 139
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- 229910000794 TRIP steel Inorganic materials 0.000 claims abstract description 54
- 238000005266 casting Methods 0.000 claims abstract description 17
- 238000005096 rolling process Methods 0.000 claims description 126
- 238000001816 cooling Methods 0.000 claims description 63
- 238000005098 hot rolling Methods 0.000 claims description 39
- 238000000137 annealing Methods 0.000 claims description 37
- 238000005097 cold rolling Methods 0.000 claims description 29
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- 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
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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
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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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
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B3/00—Rolling materials of special alloys so far as the composition of the alloy requires or permits special rolling methods or sequences ; Rolling of aluminium, copper, zinc or other non-ferrous metals
- B21B3/02—Rolling special iron alloys, e.g. stainless steel
Abstract
The aim of the present invention is to provide a method for manufacturing high-strength cold-rolled TRIP steel having a tensile strength of 590 MPa grade and low mechanical-property deviation, in which a thin-slab casting technique is employed to ensure superior workability and also significantly reduce widthwise and lengthwise mechanical-property deviation in a strip.
Description
Technical field
The present invention relates to a kind of tensile strength grade of making is the little high strength cold-rolled/hot rolling TRIP(phase change induction plasticity of 590MPa, excellent workability and mechanical property deviation) method of steel, more particularly, relate to a kind of method of utilizing the thin slab foundry engieering to make to have the little high strength cold-rolled/hot rolling TRIP steel of excellent unit elongation and mechanical property deviation.
Background technology
Recently, along with in automotive industry to the fuel efficiency that improves motor vehicle and strengthen demand to officer and passenger's safety regulations, carrying out the abundant research to the high body of motor vehicle of the intensity in light weight of anti-collision that improvement can be provided.
Therefore, for light-weight characteristics and the high characteristic of intensity that satisfies body of motor vehicle simultaneously, just developing and using the high tensile steel plate of 590MPa level or higher category in the concentrated area.In addition, mainly process by punching press owing to be used for the steel plate of motor vehicle, so they should have excellent press formability, in order to ensure such press formability, need to make the product made from steel of the phase transformation strengthening with excellent workability.In having the steel grade of phase change structure, DP(two-phase) steel and TRIP(phase change induction plasticity) steel is known high-strength steel with excellent workability.Specifically, as known in the art, because the high-elongation behavior that is caused by the phase change induction plasticity of residual austenite, so the TRIP steel is widely used in the complex-shaped parts that need have high workability.
The TRIP steel is the residual austenite steel with three-phase mixed structure that comprises ferrite and bainite that at room temperature still keeps by the austenite that allows at high temperature to exist.In this TRIP steel, the austenite strengthening element of suitable heating and cooling thermal treatment and interpolation such as C, Si, Mn etc. makes that 5%～20% austenite is at room temperature residual.When this austenite as metastable phase stood dimensional deformation mutually, it changed martensite into.When undergoing phase transition by this way, the higher and necking down resistance of work hardening exponent can increase, and makes and compares excellent workability with traditional steel.
For the method for making this high strength cold-rolled TRIP steel, be known that No. 5470529, No. 6319338, No. 6544354 and No. 6210496 United States Patent (USP) and 2003-0002581 Korean unexamined patent open, the method for making high-strength hot-rolled TRIP steel is disclosed in No. 5017248 and No. 5030298 United States Patent (USP) and No. 2015391, No. 2559272, No. 2820774 and No. 1871742 Japanese Patent.Yet these existing inventions belong to the manufacture method of utilizing traditional rolling mill technology, and these methods cause occurring the problem of the deviation of significant width aspect the mechanical property and length direction undesirably and inevitably in the actual production line.
Simultaneously, a lot of modes of paying close attention to of passing through the thin slab casting that are subjected to recently corresponding to novel process for making are made the small section mill technology of steel plate owing to the width of band steel and little the arousing attention of temperature contrast of length direction, make it possible to produce the low steel with phase change structure of deviation aspect mechanical property.Yet, as disclosing disclosed at No. 02019314 European patent, 2009-0214377 number and 2009-0151821 U.S. Patent application and WO00/055381 PCT, these inventions need to carry out the operation of cooling technology after being chiefly directed to hot rolling in the process of batching, and do not propose to utilize the manufacturing of micro-type rolling mill technology to have the method for the cold rolling TRIP steel of higher mechanical property.
Summary of the invention
Technical problem
Therefore, made the present invention under the situation of the problems referred to above that in considering prior art, occur, and one object of the present invention is to provide a kind of method that the tensile strength grade is the little high strength cold-rolled/hot rolling TRIP steel of 590MPa and mechanical property deviation of making, wherein, can adopt the thin slab foundry engieering to guarantee that excellent workability also reduces the deviation of the mechanical property of band steel on width and length direction significantly.
Technical scheme
To achieve these goals, the invention provides following manufacture method.
The invention provides a kind of method of making cold rolling TRIP steel by following step: make the steel that comprises following component by weight percentage become the thin slab that thickness is 30mm～150mm through continuous casting: 0.05%～0.20% C, 0.8%～2.0% Si, 1.2%～2.2% Mn, 0.001%～0.1% P, 0.001%～0.02% S, 0.01%～2.0% Al, 0.001%～0.02% N, 0.005%～0.1% Sb, total amount is 0.18% or incidental element still less (Cu+Cr+Ni+Sn+Pb), and the Fe of surplus and other unavoidable impurities; Make described thin slab through roughing, heating, finish rolling and batch, produce hot rolled strip thus; And the band steel after the hot rolling is handled through overpickling, cold rolling, continuous annealing and cooling heat, wherein, carry out finish rolling and make that the rolling speed difference of single band steel is 15% or lower, and carrying out cooling heat by this way handles, namely, slowly cool to 620 ℃～690 ℃ with the rate of cooling of the 1 ℃/s～20 ℃/s band steel after with continuous annealing, quench with the rate of cooling of 20 ℃/s～100 ℃/s immediately, stand isothermal transformation thermal treatment at 310 ℃～420 ℃ then.
In addition, the invention provides a kind of method of making cold rolling TRIP steel by following step: make the steel that comprises following component by weight percentage become the thin slab that thickness is 30mm～150mm through continuous casting: 0.05%～0.20% C, 0.8%～2.0% Si, 1.2%～2.2% Mn, 0.001%～0.1% P, 0.001%～0.02% S, 0.01%～2.0% Al, 0.001%～0.02% N, total amount are 0.18% or Fe and other unavoidable impurities of incidental element still less (Cu+Cr+Ni+Sn+Pb) and surplus; Make described thin slab through roughing, heating, finish rolling and batch, produce hot rolled strip thus; And the band steel after the hot rolling is handled through overpickling, cold rolling, continuous annealing and cooling heat, wherein, finish rolling is performed as in the scope of target temperature ± 20 that make the rolling temperature of finish to gauge frame fall into to be calculated by relational expression [910-225C-65Mn+15Si+10P] ℃, and carrying out cooling heat by this way handles, namely, slowly cool to 620 ℃～690 ℃ with the rate of cooling of the 1 ℃/s～20 ℃/s band steel after with continuous annealing, quench with the rate of cooling of 20 ℃/s～100 ℃/s immediately, stand isothermal transformation thermal treatment at 310 ℃～420 ℃ then.
In addition, the invention provides a kind of method of making cold rolling TRIP steel by following step: make the steel that comprises following component by weight percentage become the thin slab that thickness is 30mm～150mm through continuous casting: 0.05%～0.20% C, 0.8%～2.0% Si, 1.2%～2.2% Mn, 0.001%～0.1% P, 0.001%～0.02% S, 0.01%～2.0% Al, 0.001%～0.02% N, 0.005%～0.1% Sb, total amount are 0.18% or Fe and other unavoidable impurities of incidental element still less (Cu+Cr+Ni+Sn+Pb) and surplus; Make described thin slab through roughing, heating, finish rolling and batch, produce hot rolled strip thus; And with the band steel after the hot rolling through overpickling, cold rolling, continuous annealing and cooling heat are handled, wherein, continuous annealing is performed as and makes the continuous annealing temperature fall into by relational expression [840-120C-45Mn+25Si+34P-45N-25Cu+8Cr-30Ni] to calculate in the scope of target temperature ± 15 ° C of department, and carrying out cooling heat by this way handles, namely, slowly cool to 620 ℃～690 ℃ with the rate of cooling of the 1 ℃/s～20 ℃/s band steel after with continuous annealing, quench with the rate of cooling of 20 ℃/s～100 ℃/s immediately, stand isothermal transformation thermal treatment at 310 ℃～420 ℃ then.
In addition, the invention provides a kind of method of making cold rolling TRIP steel by following step: make the steel that comprises following component by weight percentage become the thin slab that thickness is 30mm～150mm through continuous casting: 0.05%～0.20% C, 0.8%～2.0% Si, 1.2%～2.2% Mn, 0.001%～0.1% P, 0.001%～0.02% S, 0.01%～2.0% Al, 0.001%～0.02% N, 0.005%～0.1% Sb, total amount are 0.18% or Fe and other unavoidable impurities of incidental element still less (Cu+Cr+Ni+Sn+Pb) and surplus; Make described thin slab through roughing, heating, finish rolling and batch, produce hot rolled strip thus; And with the band steel after the hot rolling through overpickling, cold rolling, continuous annealing and cooling heat are handled, wherein, carry out finish rolling and make that the rolling speed difference of single band steel is 15% or lower, finish rolling is performed as in the scope of target temperature ± 20 that make the rolling temperature of finish to gauge frame fall into to be calculated by relational expression [910-225C-65Mn+15Si+10P] ℃, continuous annealing is performed as in the scope of target temperature ± 15 that make the continuous annealing temperature fall into to be calculated by relational expression [840-120C-45Mn+25Si+34P-45N-25Cu+8Cr-30Ni] ℃, and carrying out cooling heat by this way handles, namely, slowly cool to 620 ℃～690 ℃ with the rate of cooling of the 1 ℃/s～20 ℃/s band steel after with continuous annealing, quench with the rate of cooling of 20 ℃/s～100 ℃/s immediately, stand isothermal transformation thermal treatment at 310 ℃～420 ℃ then.
In aforesaid method, preferably, carry out continuous casting with 4.5mpm or higher casting speed.In addition, preferably, roughing is performed as and makes that the surface temperature of thin slab in the roughing mill ingress is 950 ℃～1100 ℃, and the accumulation draft when roughing is 65%～90%.In addition, preferably, carry out heating by this way, that is, the band steel after the roughing is heated to 920 ℃～1150 ℃, or keeps its heat.In addition, preferably, carry out by this way and batch, that is, at 480 ℃～680 ℃ the band steel after the finish rolling is batched.In addition, preferably, carrying out cold rollingly by this way, that is, is 40% to 75% with the belt steel rolling after the pickling to draft.
The invention provides a kind of method of making hot rolling TRIP steel by following step: make the steel that comprises following component by weight percentage become the thin slab that thickness is 30mm～150mm through continuous casting: 0.06%～0.20% C, 0.8%～2.0% Si, 1.2%～2.2% Mn, 0.001%～0.1% P, 0.001%～0.02% S, 0.01%～2.0% Al, 0.001%～0.02% N, total amount is 0.18% or incidental element still less (Cu+Ni+Sn+Pb), Ti from 0.001%～0.1%, that selects among 0.001%～0.1% Nb and 0.001%～0.1% the V is one or more of, and the Fe of surplus and other unavoidable impurities; Make described thin slab through roughing, reheat, finish rolling and batch, wherein, finish rolling is performed as and makes that the rolling speed difference of single band steel is 15% or lower, and carry out by this way and batch, namely, band steel after the finish rolling is cooled off with 25 ℃/s or higher rate of cooling on runoff table, batch at 350 ℃～470 ℃ then.
In addition, the invention provides a kind of method of making hot rolling TRIP steel by following step: make the steel that comprises following component by weight percentage become the thin slab that thickness is 30mm～150mm through continuous casting: 0.06%～0.20% C, 0.8%～2.0% Si, 1.2%～2.2% Mn, 0.001%～0.1% P, 0.001%～0.02% S, 0.01%～2.0% Al, 0.001%～0.02% N, total amount is 0.18% or incidental element still less (Cu+Ni+Sn+Pb), Ti from 0.001%～0.1%, that selects among 0.001%～0.1% Nb and 0.001%～0.1% the V is one or more of, and the Fe of surplus and other unavoidable impurities; Make described thin slab through roughing, reheat, finish rolling and batch, wherein, finish rolling is performed as in the scope that the rolling temperature that makes in the finish to gauge frame falls into target temperature ± 20 that calculated by relational expression [910-225C-80Mn+15Si+10P] ℃, and carry out by this way and batch, namely, band steel after the finish rolling is cooled off with 25 ℃/s or higher rate of cooling on runoff table, batch at 350 ℃～470 ℃ then.
In addition, the invention provides a kind of method of making hot rolling TRIP steel by following step: make the steel that comprises following component by weight percentage become the thin slab that thickness is 30mm～150mm through continuous casting: 0.06%～0.20% C, 0.8%～2.0% Si, 1.2%～2.2% Mn, 0.001%～0.1% P, 0.001%～0.02% S, 0.01%～2.0% Al, 0.001%～0.02% N, total amount is 0.18% or incidental element still less (Cu+Ni+Sn+Pb), Ti from 0.001%～0.1%, that selects among 0.001%～0.1% Nb and 0.001%～0.1% the V is one or more of, and the Fe of surplus and other unavoidable impurities; Make described thin slab through roughing, reheat, finish rolling and batch, wherein, finish rolling is performed as and makes that the rolling speed difference of single band steel is 15% or lower, finish rolling is performed as in the scope that the rolling temperature that makes in the finish to gauge frame falls into target temperature ± 20 that calculated by relational expression [910-225C-80Mn+15Si+10P] ℃, and carry out by this way and batch, namely, band steel after the finish rolling is cooled off with 25 ℃/s or higher rate of cooling on runoff table, batch at 350 ℃～470 ℃ then.
In the above methods, preferably, carry out continuous casting with 4.5mpm or higher casting speed.In addition, preferably, roughing is performed as and makes that the surface temperature of thin slab in the ingress of roughing mill is 950 ℃～1100 ℃, and the accumulation draft during roughing is 65%～90%.In addition, preferably, carry out heating by this way, that is, the band steel after roughing is heated to 920 ℃～1150 ℃, or keeps its heat.
Beneficial effect
Be in the method for 590MPa, excellent workability and high strength cold-rolled/hot rolling TRIP steel that deviation is little aspect mechanical property in manufacturing tensile strength grade according to the present invention, can adopt the thin slab foundry engieering to guarantee excellent workability, and reduce the deviation of the mechanical property of band steel on width and length direction significantly, therefore produce have high-quality high strength cold-rolled/hot rolling TRIP steel.
In addition, the thin slab foundry engieering can be eliminated the reheat technology in traditional milling train, so conserve energy and boosting productivity.
In addition, therefore the steel that the thin slab technology can use in electric furnace the waste material by fusing such as scrap metal etc. to obtain improves the returnability of resource.
Description of drawings
Fig. 1 is the synoptic diagram that illustrates according to micro-type rolling mill technology of the present invention.
The description of the label the in＜accompanying drawing 〉
Embodiment
Hereinafter, will provide detailed description of the present invention.
As mentioned above, the invention belongs to and utilize the micro-type rolling mill technology of using the thin slab foundry engieering to make the method for high strength cold-rolled TRIP steel, describe briefly according to micro-type rolling mill technology of the present invention with reference to Fig. 1.Hot rolled strip by the micro-type rolling mill explained hereafter stands known cold-rolling process (pickling, cold rolling, continuous annealing, cooling heat are handled) and therefore obtains final cold rolling TRIP steel, has omitted the description to cold-rolling process.
Specifically, utilize continuous caster 10 to make thickness and be the thin slab (a) of 30mm～150mm.Compare for 200mm or thicker slab with the thickness of the continuous caster production that utilizes traditional milling train, this slab is thinner, therefore is known as thin slab.Place etc. cool off fully in the open because thickness is 200mm or thicker traditional slab, thus before carrying out hot rolling, its need be in reheating furnace reheat fully, to have 1100 ℃ or higher surface temperature.Yet, because thin slab is directly transferred to roughing mill 20, and without reheating furnace, so can utilize the heat of casting technique, therefore saved energy and greatly improved productivity.
Utilize roughing mill 20 that thin slab is rolling for having pre-determined thickness or less than the hot rolled strip of pre-determined thickness.Utilize well heater 30 to come the temperature that in this process, reduces of compensating band steel, utilize hot rolled strip (b) after finishing mill 50 will heat to be rolling to the final thickness of expectation then, by ROT(Run Out Table, runoff table) 60 cool off, utilize reeling machine 70 under predetermined temperature, finally to batch then, thereby produce the hot-rolled steel sheet of the mechanical property with expectation.
Like this, in order to compensate the difference between casting speed and the rolling speed, before finishing mill 50, arrange and batch case 40, thereby the hot rolled strip (b) that passes induction heater 30 is batched for the first time.Because having realized speed recently is 6mpm or high-speed casting technology faster, does not use the endless hot rolling technology of batching case 40 so now developing.
According to the high strength cold-rolled TRIP steel of making by micro-type rolling mill technology and cold-rolling process of the present invention by weight percentage (wt%) meter comprise: 0.05%～0.20% C, 0.8%～2.0% Si, 1.2%～2.2% Mn, 0.001%～0.1% P, 0.001%～0.02% S, 0.01%～2.0% Al, 0.001%～0.02% N, 0.005%～0.1% Sb, total amount is 0.18% or incidental element still less (Cu+Cr+Ni+Sn+Pb), and the Fe of surplus and other unavoidable impurities.Be described below effect and the amount of various elements.
C determines the austenitic ratio that does not change in annealing region, thereby and in the isothermal transformation heat treatment process, move to austenite diffusely and make austenite stable, therefore improve ductility.If the amount of C is less than 0.05%, then the ratio regular meeting of residual austenite reduces, and makes to be difficult to guarantee mechanical property desired among the present invention.On the contrary, if the amount of C surpasses 0.20%, then weldability can reduce.Therefore, preferably, the amount of C is restricted to 0.05%～0.20%.
Si is owing to the solution strengthening effect is improved the intensity of steel plate, and suppresses the deposition of cementite, C is enriched in the austenite that does not change, thereby makes austenite stable.If the amount of Si less than 0.8%, then is difficult to guarantee above-mentioned effect.On the contrary, if the amount of Si surpasses 2.0%, then coating, erosion resistance and weldability can descend.Therefore, preferably, the amount of Si is restricted to 0.8%～2.0%.
Mn is used to form austenite, and it has the solution strengthening effect, and is effective aspect the rate of diffusion that reduces C, and is suppressed at the transformation in the process of cooling.If the amount of Mn less than 1.2%, then is difficult to guarantee the amount of residual austenite and is difficult to guarantee intensity desired among the present invention.On the contrary, if the amount of Mn surpasses 2.2%, then the diffusion of the C during whole isothermal retention time can become insufficient, and austenitic stability deterioration on the contrary.Therefore, preferably, the amount of Mn is restricted to 1.2%～2.2%.
P strengthens steel plate by the solution strengthening effect, and when adding with Si, promotes the C enrichment in the austenite during isothermal transformation thermal treatment.If the amount of P less than 0.001%, then can not be guaranteed its effect, and manufacturing cost can increase.On the contrary, if the amount of P surpasses 0.1%, then spot weld is understood deterioration, and fragility can increase.Therefore, preferably, the amount of P is restricted to 0.001%～0.1%.
S causes the segregation of slab as the impurity element in the steel, and the ductility of steel plate and weldability are reduced.Be difficult to the amount of S is controlled to be less than 0.001%.If the amount of S surpasses 0.02%, the problem such as the segregation of slab etc. then can occur, and the ductility of steel plate and weldability can reduce.Therefore, preferably, the amount of S is restricted to 0.001%～0.02%.
The O of the molten Al of acid in steel is combined, thereby produces deoxidation, and similar to Si, and by the C in the ferrite is distributed to austenite, sour molten Al is effective to austenitic stablizing.Less than 0.01%, then can not guarantee above-mentioned effect as the amount of the molten Al of tartaric acid.On the contrary, exceed 2.0% as the amount of the molten Al of tartaric acid, then above-mentioned effect is by saturated, and inclusion and manufacturing cost can increase together.Therefore, preferably, the amount of sour molten Al is restricted to 0.01%～2.0%.
The stable austenite of N is effective.If the amount of N less than 0.001%, then is difficult to guarantee above-mentioned effect.On the contrary, if the amount of N surpasses 0.02%, then above-mentioned effect is by saturated, and weldability and manufacturing cost can increase.Therefore, preferably, the amount of N is restricted to 0.001%～0.02%.
Therefore the surface enrichment of Sb inhibited oxidation thing reduces surface imperfection, and Sb is being very effective aspect the formation that suppresses the uneven surface enriched products.If the amount of Sb is less than 0.005%, then be difficult to guarantee above-mentioned effect.On the contrary, if the amount of Sb surpasses 0.1%, then above-mentioned effect is by saturated, and can cause the problem relevant with the deterioration of manufacturing cost and workability.Therefore, preferably, the amount of Sb is restricted to 0.005%～0.1%.
Incidental element (Cu+Cr+Ni+Sn+Pb) is the impurity element that is brought by the waste material that is used as charging in process for making.If their total amount surpasses 0.18%, then can cause the surface crack of thin slab casting stream.Therefore, preferably, the total amount of these elements is restricted to 0.18% or still less.
Except top component, the present invention includes Fe and other unavoidable impurities of equal amount.
Describe molten steel that utilization according to the present invention comprises said components below in detail and make the method for high strength cold-rolled TRIP steel.
Mention with reference to Fig. 1 as top, the present invention includes: micro-type rolling mill hot rolling technology, this technology comprise continuous casting, roughing, heating, finish rolling, cool off and batch; Cold-rolling process comprises that pickling, cold rolling, continuous annealing and cooling heat handles, and characteristic technology of the present invention constitutes and is to make the little high strength cold-rolled TRIP steel of mechanical property deviation by the operational condition of controlling each step again.
Specifically, preferably, with 4.5mpm or cast speed faster and carry out continuous casting.Typically, compare with soft product, tensile strength be the ladle content of 590MPa or higher category bigger such as elements (add these yuan and usually guarantee intensity) such as C, Mn, Si, the therefore easier segregation that strand occurs under lower casting speed.When segregation occurring by this way, be difficult to guarantee intensity, and the horizontal or along track bias of mechanical property can occur.Therefore, casting speed is set to 4.5mpm or faster.
The roughing mill that is equipped with 2～4 supports by use makes continuous-casting sheet billet stand roughing and carries out described roughing.Like this, preferably, carry out this technology, make that the surface temperature of thin slab in the roughing mill ingress is 950 ℃～1100 ℃, and the accumulation draft when making roughing is 65%～90%.
If the surface temperature of thin slab in the roughing mill ingress is lower than 950 ℃, then roughing load meeting greatly increases, and limit portion crackle can occur.On the contrary, if its surface temperature is higher than 1100 ℃, then may produce San-Su type firecoat.Therefore, this surface temperature is restricted to 950 ℃～1100 ℃.
In addition, the accumulation draft during roughing is considered to important, to obtain the product of the expectation with uniform mechanical property among the present invention.Draft during along with roughing increases, and the micro-distribution of making Mn, Si that the TRIP steel is required important element, Al etc. is become evenly, and in addition, width and the thermograde on the thickness direction of band steel can reduce, so obtain uniform mechanical property.Yet, if the accumulation draft can not show above effect fully less than 65%.On the contrary, if the accumulation draft surpasses 90%, then the rolling deformation resistance enlarges markedly, and therefore increases manufacturing cost.Therefore, preferably, be that 65%～90% mode is rolled with the accumulation draft.
Preferably, carry out heating by this way, that is, the band steel after the roughing is heated to 920 ℃～1150 ℃ or keep its heat again.If the surface temperature of the band steel after the roughing is lower than 920 ℃, then the rolling deformation resistance can enlarge markedly.On the contrary, if its surface temperature is higher than 1150 ℃, then needs the high cost of energy temperature that raises, and can occur surperficial firecoat defective more continually.Therefore, preferably, Heating temperature is restricted to 920 ℃～1150 ℃.
Preferably, finish rolling is performed as and makes that the difference of rolling speed of single band steel is 15% or lower.Because the high strength cold-rolled TRIP steel according to 590MPa level of the present invention uses phase-change organization as schedule of reinforcement, thus mechanical property can be based on finish rolling the time rolling speed and change.Surpass 15% if having the difference of the rolling speed in the finishing mill of support, then be difficult to obtain uniform rate of cooling at follow-up runoff table, and be difficult to the coiling temperature that obtains to expect, and therefore can enlarge markedly at the width of band steel or the deviation of the mechanical property on the length direction.
In addition, in finish-rolling process, preferably the rolling temperature of finish to gauge frame is set in the scope that falls into target temperature ± 20 that calculated by relational expression [910-225C-65Mn+15Si+10P] ℃.In traditional hot rolling technology, typically, make finish rolling be equal to or higher than Ar
3Finish under the temperature of transition temperature, have the TRIP steel of mechanical property as far as possible uniformly with manufacturing.Yet, in the present invention, with the final rolling temperature of finish to gauge frame at Ar
1Transition temperature and Ar
3Mode between the transition temperature is carried out under the rolling situation, that is, carry out under the rolling situation in the two-phase region of austenite and ferrite coexistence, has improved unit elongation under same intensity, and this test by repeatedly is confirmed.
Using the thin slab foundry engieering to make under the situation of TRIP steel plate, compare with traditional hot rolling technology, control easier advantage owing to have the temperature of band steel, so preferably, final rolling temperature is set at Ar
1Transition temperature and Ar
3Between the transition temperature.In the present invention, it should be noted that, said temperature can change according to the type of component, and the rolling condition in the scope of target temperature ± 20 that calculated by relational expression [910-225C-65Mn+15Si+10P] ℃ helps in two-phase region rolling, and this is confirmed by test repeatedly.
Explain by testing the result who confirms repeatedly by following theory explanation.For example, under the situation of the steel with phase-change organization, in order to improve intensity and ductility simultaneously, austenite stable element such as C, Mn etc. is enriched in the austenite that does not change is considered to important.Carry out under the situation of finish rolling in two-phase region, the dispersion behavior of solute element is improved, therefore, even under the situation that has same component, ferrite is cleaned, and simultaneously austenite is further stablized, even and these effects also lasting after cold rolling and annealing.
In addition, preferably, carry out by this way and batch, that is, the band steel after the finish rolling batches with 480 ℃～680 ℃ temperature.If the hot rolling reeling temperature is lower than 480 ℃, then hot rolling intensity increases greatly, but causes the problem of cold-rolling property undesirably.On the contrary, if this coiling temperature is higher than 680 ℃, the band coil of strip easy deformation after the hot rolling then.Therefore, this temperature preferably is restricted to 480 ℃～680 ℃.
Preferably, carry out cold rollingly by this way, that is, the band steel after the pickling is rolled with 40%～75% draft.If draft less than 40%, then recrystallization can not occur when annealing.On the contrary, if draft surpasses 75%, then the rolling deformation resistance increases greatly, make be difficult to carry out rolling.Therefore, draft preferably is restricted to 40%～75%.
In addition, preferably, carry out continuous annealing by this way, that is, and in the scope of target temperature ± 15 that the continuous annealing temperature fallen into calculated by relational expression [840-120C-45Mn+25Si+34P-45N-25Cu+8Cr-30Ni] ℃.When making the TRIP steel, in the zone of austenite and ferrite coexistence, carry out annealing, this is being favourable aspect mechanical property of guaranteeing to expect.By test repeatedly, by form the coexistence that changes based on main alloy element and incidental element such as C, Mn, Si etc. empirically, the relational expression above determining is to obtain better mechanical property.
If temperature is than low 15 ℃ of the value of being calculated by top relational expression, then austenitic ratio is low excessively, perhaps recrystallization can not occur.On the contrary, if annealing thermal treatment is carried out under the temperature higher 15 ℃ than target temperature, then austenitic ratio is too high, and the concentration of the C in the austenite can be diluted, therefore the ratio regular meeting of the residual austenite in the final tissue reduces, and the ratio regular meeting of martensite or bainite increases.In addition, the mass flow of band steel can be owing to the high temperature problem that become.Therefore, preferably, annealing temperature is restricted to above-mentioned condition.
At last, preferably, carrying out cooling heat by this way handles, namely, slowly cool to 620 ℃～690 ℃ with the rate of cooling of the 1 ℃/s～20 ℃/s band steel after with continuous annealing, quench with the rate of cooling of 20 ℃/s～100 ℃/s immediately, make it stand isothermal transformation thermal treatment at 310 ℃～420 ℃ then.
Specifically, in the time will being with steel to slowly cool to 620 ℃～690 ℃, if carry out cooling with the temperature that is lower than 620 ℃, then may deposit carbide.On the contrary, if carry out cooling with the temperature that is higher than 690 ℃, then austenite can not be stablized effectively.In addition, in process of cooling, if rate of cooling less than 1 ℃/s, then productivity can significantly reduce.On the contrary, if the back rate of cooling surpasses 20 ℃/s, then the diffusion of the C in the austenite in process of cooling becomes insufficient.
In addition, quenching immediately with the rate of cooling of 20 ℃/s～100 ℃/s and making it when standing isothermal transformation thermal treatment for 310 ℃～420 ℃, if carry out quenching with the speed that is lower than 20 ℃/s, perlitic transformation then can take place or wherein deposit the bainite transformation of cementite, make to be difficult to obtain residual austenite, reduce ductility undesirably.On the contrary, if speed surpasses 100 ℃/s, then in follow-up isothermal transformation thermal treatment, the bainite transformation that does not wherein deposit cementite is postponed, therefore obtain block thick annealed structure, cause ductility to reduce undesirably.
When isothermal transformation thermal treatment, if temperature is lower than 310 ℃, then the C enrichment in the austenite becomes insufficient.On the contrary, if temperature is higher than 420 ℃, then can make depositions such as cementite, cause ductility to reduce undesirably.Therefore, preferably, be above-mentioned condition with this temperature limitation.
In order to assess technique effect of the present invention, carry out following test.
Use has the steel of the composition as shown in following table 1, make each hot rolled strip under the operational condition of the slab thickness in comprising table 2, casting speed, steel slab surface temperature, rolling speed difference, final rolling temperature and annealing temperature, and measure the mechanical property (tensile strength, unit elongation and aberrations in property) of band steel and the generation of surperficial firecoat.Shown in result's table 2 below.
In table 1, the 1st～No. 5 steel is to utilize thin slab foundry engieering (slab thickness: the 84mm) hot rolled strip of Zhi Zaoing, the 6th and No. 7 steel (slab thickness: 230mm) be the hot rolled strip of making under traditional milling train condition.
In table 2, the steel slab surface thermometer is shown in and is right after roughing measured surface temperature before.Rolling speed difference is by representing by the percent value that obtains that the biggest quality flow rate in the single band steel when finish to gauge is rolling and the difference between the minimum mass flow rate and mass flow rate rate are divided by, wherein, rolling speed difference is low means that rolling rate variations is little.Whether final rolling temperature shows carries out rollingly in the scope of the target temperature that is calculated by relational expression 1 ± 20 ℃, so compared steel 4,7 and 8 is by corresponding to Ar
3Carry out rolling the acquisition under the temperature of the single phase region directly over the transition temperature.
In the condition of the 1st～No. 5 steel of table 2, the Heating temperature of the band steel after roughing is set to 1075 ℃, and in the condition of the 6th and No. 7 steel, Heating temperature is set to 1200 ℃, and the thickness of the band steel after the hot rolling is set to 3.2mm.
Band steel after the hot rolling is carried out pickling, then with draft be 56.3% carry out cold rolling, therefore produce the cold rolled strip that thickness is 1.4mm, band steel after cold rolling to each under the annealing temperature of table 2 carries out full annealed, rate of cooling with 7 ℃/s slowly cools to 650 ℃, cool off with the rate of cooling of about 70 ℃/s immediately, and stand isothermal transformation thermal treatment at 380 ℃～410 ℃.
[table 1]
[table 2]
Relational expression 1=[910-225C-65Mn+15Si+10P]
Relational expression 2=[840-120C-45Mn+25Si+34P-45N-25Cu+8Cr-30Ni]
In table 2, tensile strength is in JIS(Japanese Industrial Standards with unit elongation) value measured along the direction place vertical with rolling direction of the 4/w position of No. 5 test sample book.Unit elongation is represented that by the per-cent of the tension strain that acts on until the fracture of stretching sample aberrations in property is represented by deducting the value that minimum value obtains from the maximum value the performance number of measuring along length and the width of coil of strip.In addition, TS * EI(tensile strength * unit elongation) be the parameter of the superiority of unit elongation performance (wherein, unit elongation reduces along with the increase of intensity) that high-strength steel is shown, wherein, TS * EI height means that tensile strength and unit elongation are all high.
Be clear that as the result from table 2, according to the present invention, can produce and have excellent unit elongation and the high strength cold-rolled TRIP steel of TS * EI and low-down mechanical property deviation.
Simultaneously, according to high-strength hot-rolled TRIP steel of the present invention by weight percentage (wt%) meter comprise: 0.06%～0.20% C, 0.8%～2.0% Si, 1.2%～2.2% Mn, 0.001%～0.1% P, 0.001%～0.02% S, 0.01%～2.0% Al, 0.001%～0.02% N, total amount be 0.18% or still less incidental element (Cu+Ni+Sn+Pb), Ti, 0.001%～0.1% Nb from 0.001%～0.1% and 0.001%～0.1% V select one or more of, and the Fe of surplus and other unavoidable impurities.Be described below effect and the amount of various elements.
C makes austenite stable, and has therefore increased at room temperature residual austenitic amount, therefore improves ductility.If the amount of C is then austenitic than the regular meeting reduction less than 0.06%, make to be difficult to guarantee mechanical property desired among the present invention.On the contrary, if the amount of C surpasses 0.20%, then weldability can reduce.Therefore, preferably, the amount of C is restricted to 0.06%～0.20%.
Si is owing to the solution strengthening effect is improved the intensity of steel plate, and suppresses the deposition of cementite, therefore promotes C enrichment in the austenite that does not change, thereby makes austenite stable.If the amount of Si less than 0.8%, then is difficult to guarantee above-mentioned effect.On the contrary, if the amount of Si surpasses 2.0%, then coating, erosion resistance and weldability can descend.Therefore, preferably, the amount of Si is restricted to 0.8%～2.0%.
Mn makes austenite stable, and it has the solution strengthening effect, and is suppressed at the transformation in the process of cooling.If the amount of Mn less than 1.2%, then is difficult to guarantee the amount of residual austenite and is difficult to guarantee intensity desired among the present invention.On the contrary, if the amount of Mn surpasses 2.2%, the hot rolling problem that can become then.Therefore, preferably, the amount of Mn is restricted to 1.2%～2.2%.
P strengthens steel plate by solution strengthening, and when adding with Si, promotes the C enrichment in the austenite.If the amount of P less than 0.001%, then can not be guaranteed its effect, and manufacturing cost can increase.On the contrary, if the amount of P surpasses 0.1%, then spot weld is understood deterioration, and fragility can increase.Therefore, preferably, the amount of P is restricted to 0.001%～0.1%.
S causes the segregation of slab as the impurity element in the steel, and the ductility of steel plate and weldability are reduced.Be difficult to the amount of S is controlled to be less than 0.001%.If the amount of S surpasses 0.02%, the problem such as the segregation of slab etc. then can occur, and the ductility of steel plate and weldability can reduce.Therefore, preferably, the amount of S is restricted to 0.001%～0.02%.
The O of the molten Al of acid in steel is combined, thereby produces deoxidation, and similar to Si, and by the C in the ferrite is distributed to austenite, sour molten Al is effective to austenitic stablizing.Less than 0.01%, then can not guarantee above-mentioned effect as the amount of the molten Al of tartaric acid.On the contrary, exceed 2.0% as the amount of the molten Al of tartaric acid, then above-mentioned effect is by saturated, and inclusion and manufacturing cost can increase together.Therefore, preferably, the amount of sour molten Al is restricted to 0.01%～2.0%.
The stable austenite of N is effective.If the amount of N less than 0.001%, then is difficult to expect above-mentioned effect.On the contrary, if the amount of N surpasses 0.02%, then above-mentioned effect is by saturated, and weldability can reduce and manufacturing cost can increase.Therefore, preferably, the amount of N is restricted to 0.001%～0.02%.
Incidental element (Cu+Ni+Sn+Pb) is the impurity element that is brought by the waste material that is used as charging in process for making.If their total amount surpasses 0.18%, then can cause the surface crack of thin slab casting stream.Therefore, preferably, the total amount of these elements is restricted to 0.18% or still less.
Therefore the steel composition that forms also can be added with select one or more of from Ti, Nb and V.Though the fundamental property of desired high strength cold-rolled TRIP steel does not produce decisive influence among these elements such as the present invention, preferably, add one or more of in them, with tensile strength, yield strength and the surface quality of accurately controlling product.
Ti, Nb and V are effective to yield strength and the realization fine grain size aspect that improves steel plate.If the amount of these elements less than 0.001%, then is difficult to guarantee above-mentioned effect.On the contrary, if their amount surpasses 0.1%, then manufacturing cost can increase and can form too much settling, and this is the ferritic ductility of deterioration undesirably.Therefore, the amount of Ti, Nb and V is restricted to 0.001% to 0.1%.
Except top component, the present invention includes Fe and other unavoidable impurities of equal amount.
Describe molten steel that utilization according to the present invention comprises said components below in detail and make the method for high-strength hot-rolled TRIP steel.
Mention with reference to Fig. 1 as top, micro-type rolling mill technology comprises continuous casting, roughing, heating, finish rolling, cools off and batches, and characteristic technology of the present invention constitutes the high-strength hot-rolled TRIP steel that is to have by the operational condition manufacturing of controlling each step again low mechanical property deviation.
Specifically, preferably, with 4.5mpm or cast speed faster and carry out continuous casting.Typically, compare with soft product, tensile strength be the ladle content of 590MPa or higher category more such as elements (add these yuan and usually guarantee intensity) such as C, Mn, Si, the therefore easier segregation that strand occurs under lower casting speed.When segregation occurring by this way, be difficult to guarantee intensity, the horizontal or along track bias of mechanical property perhaps can appear.Therefore, casting speed is set to 4.5mpm or faster.
The roughing mill that is equipped with 2～4 supports by use makes continuous-casting sheet billet stand roughing and carries out described roughing.Like this, preferably, carry out this technology, make that the surface temperature of thin slab in the roughing mill ingress is 950 ℃～1100 ℃, and the accumulation draft when making roughing is 65%～90%.
If the surface temperature of thin slab in the roughing mill ingress is lower than 950 ℃, then roughing load meeting greatly increases, and limit portion crackle can occur.On the contrary, if its surface temperature is higher than 1100 ℃, then can produce so-called San-Su type firecoat.Therefore, this surface temperature is restricted to 950 ℃～1100 ℃.
In addition, the accumulation draft when roughing is considered to important, to obtain the product of the expectation with uniform mechanical property among the present invention.Along with the draft when the roughing increases, can become even to the micro-distribution of making Mn, Si that the TRIP steel is required important element, Al etc., in addition, width and the thermograde on the thickness direction of band steel can reduce, and therefore obtain uniform mechanical property.Yet, if the accumulation draft can not show above effect fully less than 65%.On the contrary, if the accumulation draft surpasses 90%, then the rolling deformation resistance enlarges markedly, and therefore increases manufacturing cost.Therefore, preferably, be that 65%～90% mode is carried out rolling with the accumulation draft.
Preferably, carry out heating by this way, that is, the band steel after the roughing is heated to 920 ℃～1150 ℃ or keep its heat again.If the surface temperature of the band steel after the roughing is lower than 920 ℃, then the rolling deformation resistance can enlarge markedly.On the contrary, if its surface temperature is higher than 1150 ℃, then need high cost of energy to improve temperature, and can occur surperficial firecoat defective more continually.Therefore, preferably, Heating temperature is restricted to 920 ℃～1150 ℃.
Preferably, finish rolling is performed as and makes that the difference of rolling speed of single band steel is 15% or lower.Because the high-strength hot-rolled TRIP steel according to 590MPa level of the present invention uses phase-change organization as schedule of reinforcement, thus mechanical property can be based on finish rolling the time rolling speed and change.If the difference of the rolling speed in the finishing mill surpasses 15%, then be difficult to obtain uniform rate of cooling at follow-up runoff table, and be difficult to the coiling temperature that obtains to expect, and therefore can enlarge markedly at the width of band steel or the deviation of the mechanical property on the length direction.
In addition, in finish-rolling process, preferably the rolling temperature with the finish to gauge frame is set in the scope that falls into the target temperature ± 20 ° C that is calculated by relational expression [910-225C-80Mn+15Si+10P].In traditional hot rolling technology, typically be equal to or higher than Ar
3The temperature of transition temperature gets off to finish finish rolling, has the TRIP steel of mechanical property as far as possible uniformly with manufacturing.Yet, in the present invention, make the final rolling temperature of finish to gauge frame at Ar rolling being performed as
1Transition temperature and Ar
3Under the situation between the transition temperature, namely carry out under the rolling situation in the two-phase region of austenite and ferrite coexistence, improved unit elongation under same intensity, this confirms by testing repeatedly.
Utilizing the thin slab foundry engieering to make under the situation of TRIP steel plate, preferably, controlling easier advantage by utilizing the temperature of comparing the band steel with traditional hot rolling technology, final rolling temperature is being set at Ar
1And Ar
3Between the transition temperature.In the present invention, what note is, said temperature can change according to the kind of component, and the rolling condition in the scope of the target temperature ± 20 ° C that is calculated by relational expression [910-225C-80Mn+15Si+10P] is conducive to be rolled in two-phase region, and this confirms by testing repeatedly.
Explain by testing the result who confirms repeatedly by following theory explanation.For example, under the situation of the steel with phase-change organization, in order to improve intensity and ductility simultaneously, austenite stable element such as C, Mn etc. is enriched in the austenite that does not change is considered to important.Carry out under the situation of finish rolling in two-phase region, the distribution behavior of solute element is improved, and therefore, even under the situation that has same component, ferrite is cleaned, and austenite is further stablized simultaneously.
In addition, carry out cooling by this way, that is, and the band steel cooling after making finish rolling with 25 ℃/s or higher rate of cooling on the runoff table, and batch at 350 ℃～470 ℃.If the rate of cooling on runoff table is less than 25 ℃/s, then the austenite stable element such as C, Mn etc. can deposit to the perlite from austenite, therefore can make the concentration effect deterioration.Therefore, rate of cooling is restricted to 25 ℃ or higher.
If the hot rolling reeling temperature is lower than 350 ℃, then form martensite, and therefore intensity increases greatly, but unit elongation can reduce.On the contrary, if the hot rolling reeling temperature is higher than 470 ℃, then therefore the deposition of the cementite in the steel suppresses the formation of residual austenite.Therefore, the hot rolling reeling temperature preferably is restricted to 380 ℃～490 ℃.
Finish rolling and to curl be that characteristic technology of the present invention constitutes can be to both or more combination the in them, therefore produces the hot rolling TRIP steel of the tensile strength with 590MPa level desired among the present invention and low mechanical property deviation.
In order to assess technique effect of the present invention, the test below carrying out.
Use has the steel of the composition as shown in following table 3, make each hot rolled strip under the operational condition of the slab thickness in comprising table 4, casting speed, steel slab surface temperature, rolling speed difference etc., and measure the mechanical property (tensile strength, unit elongation and aberrations in property) of band steel and the generation of being with the surperficial firecoat of steel.Shown in result's table 2 below.
In table 3, in the steel of all numberings, the total amount of incidental element (Cu+Ni+Sn+Pb) is controlled as 0.18% or lower.In addition, the 1st～No. 6 steel is to utilize thin slab foundry engieering (slab thickness: the 84mm) hot rolled strip of Zhi Zaoing, the 7th and No. 8 steel (slab thickness: 230mm) be the hot rolled strip of making under traditional milling train condition.
In table 4, the steel slab surface thermometer is shown in and is right after roughing measured surface temperature before.Accumulation draft when roughing is represented divided by the percent value that slab thickness obtains by the difference between the slab thickness (84mm) of the ingress of roughing mill and the slab thickness (mm) in the exit of roughing mill.Rolling speed difference is represented by the biggest quality flow rate in the single band steel when finish to gauge is rolling and the difference between the minimum mass flow rate and the mass flow rate rate percent value that obtains of being divided by, wherein, rolling speed difference is low means that rolling rate variations is little.Whether final rolling temperature shows carries out rollingly in the scope of target temperature ± 20 of being calculated by relational expression 3 ℃, so compared steel 5,8 and 9 is passed through corresponding to Ar
3Carry out rolling the acquisition under the temperature of the single phase region directly over the transition temperature.
Under the condition of No. 1～No. 6 steel of table 4, the Heating temperature of the band steel after roughing is set to 1060 ℃, and under the condition of No. 7 and No. 8 steel, the reheat temperature is set to 1200 ℃.Rate of cooling in the steel of all numberings on runoff table is set to about 70 ℃/s, and the final thickness of the band steel after the hot rolling is set to 3.0mm.
[table 3]
Relational expression 3=[910-225C-80Mn-15Si+10P]
[table 4]
In table 4, tensile strength and unit elongation are along the value of the directional survey vertical with rolling direction in the 4/w position of JIS5 test sample book.Unit elongation is represented that by the per-cent of the tension strain that acts on until the sample fracture aberrations in property is represented by deducting the value that minimum value obtains from the maximum value the performance number of measuring along length and the width of coil of strip.In addition, TS * EI(tensile strength * unit elongation) be the parameter of the superiority of unit elongation performance (wherein, unit elongation reduces along with the increase of intensity) that high-strength steel is shown, wherein, TS * EI height means that tensile strength and unit elongation are all high.
As being clear that by the result from table 4, according to the present invention, can produce extensible rate and TS * EI and the low high-strength hot-rolled TRIP steel of mechanical property deviation with excellence.
Claims (15)
1. make the method that the tensile strength grade is 590MPa, excellent workability and the high strength cold-rolled TRIP steel that deviation is little aspect mechanical property for one kind, this method comprises the steps:
Make the steel that comprises following component by weight percentage become the thin slab that thickness is 30mm～150mm through continuous casting: 0.05%～0.20% C, 0.8%～2.0% Si, 1.2%～2.2% Mn, 0.001%～0.1% P, 0.001%～0.02% S, 0.01%～2.0% Al, 0.001%～0.02% N, 0.005%～0.1% Sb, total amount are 0.18% or Fe and other unavoidable impurities of incidental element Cu+Cr+Ni+Sn+Pb still less and surplus; Make described thin slab through roughing, heating, finish rolling and batch, produce hot rolled strip thus; And the band steel after the hot rolling is handled through overpickling, cold rolling, continuous annealing and cooling heat, thereby is produced cold rolling TRIP steel,
Wherein, carry out finish rolling and make that the rolling speed difference of single band steel is 15% or lower, and
Carrying out cooling heat by this way handles: slowly cool to 620 ℃～690 ℃ with the rate of cooling of the 1 ℃/s～20 ℃/s band steel after with continuous annealing, quench with the rate of cooling of 20 ℃/s～100 ℃/s immediately, stand isothermal transformation thermal treatment at 310 ℃～420 ℃ then.
2. make the method that the tensile strength grade is 590MPa, excellent workability and the high strength cold-rolled TRIP steel that deviation is little aspect mechanical property for one kind, this method comprises the steps:
Make the steel that comprises following component by weight percentage become the thin slab that thickness is 30mm～150mm through continuous casting: 0.05%～0.20% C, 0.8%～2.0% Si, 1.2%～2.2% Mn, 0.001%～0.1% P, 0.001%～0.02% S, 0.01%～2.0% Al, 0.001%～0.02% N, 0.005%～0.1% Sb, total amount are 0.18% or Fe and other unavoidable impurities of incidental element Cu+Cr+Ni+Sn+Pb still less and surplus; Make described thin slab through roughing, heating, finish rolling and batch, produce hot rolled strip thus; And the band steel after the hot rolling is handled through overpickling, cold rolling, continuous annealing and cooling heat, thereby is produced cold rolling TRIP steel,
Wherein, finish rolling is performed as in the scope of target temperature ± 20 that make the rolling temperature of finish to gauge frame fall into to be calculated by relational expression [910-225C-65Mn+15Si+10P] ℃, and
Carrying out cooling heat by this way handles: slowly cool to 620 ℃～690 ℃ with the rate of cooling of the 1 ℃/s～20 ℃/s band steel after with continuous annealing, quench with the rate of cooling of 20 ℃/s～100 ℃/s immediately, stand isothermal transformation thermal treatment at 310 ℃～420 ℃ then.
3. make the method that the tensile strength grade is 590MPa, excellent workability and the high strength cold-rolled TRIP steel that deviation is little aspect mechanical property for one kind, this method comprises the steps:
Make the steel that comprises following component by weight percentage become the thin slab that thickness is 30mm～150mm through continuous casting: 0.05%～0.20% C, 0.8%～2.0% Si, 1.2%～2.2% Mn, 0.001%～0.1% P, 0.001%～0.02% S, 0.01%～2.0% Al, 0.001%～0.02% N, 0.005%～0.1% Sb, total amount are 0.18% or Fe and other unavoidable impurities of incidental element Cu+Cr+Ni+Sn+Pb still less and surplus; Make described thin slab through roughing, heating, finish rolling and batch, produce hot rolled strip thus; And the band steel after the hot rolling is handled through overpickling, cold rolling, continuous annealing and cooling heat, thereby is produced cold rolling TRIP steel,
Wherein, continuous annealing is performed as in the scope of target temperature ± 15 that make the continuous annealing temperature fall into to be calculated by relational expression [840-120C-45Mn+25Si+34P-45N-25Cu+8Cr-30Ni] ℃, and
Carrying out cooling heat by this way handles: slowly cool to 620 ℃～690 ℃ with the rate of cooling of the 1 ℃/s～20 ℃/s band steel after with continuous annealing, quench with the rate of cooling of 20 ℃/s～100 ℃/s immediately, stand isothermal transformation thermal treatment at 310 ℃～420 ℃ then.
4. make the method that the tensile strength grade is 590MPa, excellent workability and the high strength cold-rolled TRIP steel that deviation is little aspect mechanical property for one kind, this method comprises the steps:
Make the steel that comprises following component by weight percentage become the thin slab that thickness is 30mm～150mm through continuous casting: 0.05%～0.20% C, 0.8%～2.0% Si, 1.2%～2.2% Mn, 0.001%～0.1% P, 0.001%～0.02% S, 0.01%～2.0% Al, 0.001%～0.02% N, 0.005%～0.1% Sb, total amount are 0.18% or Fe and other unavoidable impurities of incidental element Cu+Cr+Ni+Sn+Pb still less and surplus; Make described thin slab through roughing, heating, finish rolling and batch, produce hot rolled strip thus; And the band steel after the hot rolling is handled through overpickling, cold rolling, continuous annealing and cooling heat, thereby is produced cold rolling TRIP steel,
Wherein, carry out finish rolling and make that the rolling speed difference of single band steel is 15% or lower,
Finish rolling is performed as in the scope of target temperature ± 20 that make the rolling temperature of finish to gauge frame fall into to be calculated by relational expression [910-225C-65Mn+15Si+10P] ℃,
Continuous annealing is performed as in the scope of target temperature ± 15 that make the continuous annealing temperature fall into to be calculated by relational expression [840-120C-45Mn+25Si+34P-45N-25Cu+8Cr-30Ni] ℃, and
Carrying out cooling heat by this way handles: slowly cool to 620 ℃～690 ℃ with the rate of cooling of the 1 ℃/s～20 ℃/s band steel after with continuous annealing, with the rate of cooling of 20 ℃/s～100 ℃/s, stand isothermal transformation thermal treatment at 310 ℃～420 ℃ then immediately.
5. as any described method of claim 1 to the claim 4, wherein, carry out continuous casting with 4.5mpm or higher casting speed.
6. as any described method of claim 1 to the claim 4, wherein, carry out roughing and make that the surface temperature of thin slab in the roughing mill ingress is 950 ℃～1100 ℃, and the accumulation draft when roughing is 65% to 90%.
7. as any described method of claim 1 to the claim 4, wherein, carry out heating by this way: the band steel after the roughing is heated to 920 ℃～1150 ℃ or keep its heat.
8. as any described method of claim 1 to the claim 4, wherein, carry out by this way and batch: at 480 ℃～680 ℃ the band steel after the finish rolling is batched.
9. as any described method of claim 1 to the claim 4, wherein, carry out cold rolling by this way: be 40% to 75% with the belt steel rolling after the pickling to draft.
10. make the method that the tensile strength grade is the little high-strength hot-rolled TRIP steel of 590MPa, excellent workability and mechanical property aspect deviation for one kind, this method comprises the steps:
Make the steel that comprises following component by weight percentage become the thin slab that thickness is 30mm～150mm through continuous casting: 0.06%～0.20% C, 0.8%～2.0% Si, 1.2%～2.2% Mn, 0.001%～0.1% P, 0.001%～0.02% S, 0.01%～2.0% Al, 0.001%～0.02% N, total amount be 0.18% or the V of incidental element Cu+Ni+Sn+Pb still less, the Ti from 0.001%～0.1%, 0.001%～0.1% Nb and 0.001%～0.1% select one or more of, and the Fe of surplus and other unavoidable impurities; Make described thin slab through roughing, reheat, finish rolling and batch, thereby produce hot rolling TRIP steel,
Wherein, finish rolling is performed as and makes that the rolling speed difference of single band steel is 15% or lower, and
Carry out by this way and batch: the band steel after the finish rolling is cooled off with 25 ℃/s or higher rate of cooling on runoff table, batch at 350 ℃～470 ℃ then.
11. make the method that the tensile strength grade is the little high-strength hot-rolled TRIP steel of 590MPa, excellent workability and mechanical property aspect deviation for one kind, this method comprises the steps:
Make the steel that comprises following component by weight percentage become the thin slab that thickness is 30mm～150mm through continuous casting: 0.06%～0.20% C, 0.8%～2.0% Si, 1.2%～2.2% Mn, 0.001%～0.1% P, 0.001%～0.02% S, 0.01%～2.0% Al, 0.001%～0.02% N, total amount be 0.18% or the V of incidental element Cu+Ni+Sn+Pb still less, the Ti from 0.001%～0.1%, 0.001%～0.1% Nb and 0.001%～0.1% select one or more of, and the Fe of surplus and other unavoidable impurities; Make described thin slab through roughing, reheat, finish rolling and batch, thereby produce hot rolling TRIP steel,
Wherein, finish rolling is performed as in the scope that the rolling temperature that makes in the finish to gauge frame falls into target temperature ± 20 that calculated by relational expression [910-225C-80Mn+15Si+10P] ℃, and
Carry out by this way and batch: the band steel after the finish rolling is cooled off with 25 ℃/s or higher rate of cooling on runoff table, batch at 350 ℃～470 ℃ then.
12. make the method that the tensile strength grade is the little high-strength hot-rolled TRIP steel of 590MPa, excellent workability and mechanical property aspect deviation for one kind, this method comprises the steps:
Make the steel that comprises following component by weight percentage become the thin slab that thickness is 30mm～150mm through continuous casting: 0.06%～0.20% C, 0.8%～2.0% Si, 1.2%～2.2% Mn, 0.001%～0.1% P, 0.001%～0.02% S, 0.01%～2.0% Al, 0.001%～0.02% N, total amount be 0.18% or the V of incidental element Cu+Ni+Sn+Pb still less, the Ti from 0.001%～0.1%, 0.001%～0.1% Nb and 0.001%～0.1% select one or more of, and the Fe of surplus and other unavoidable impurities; Make described thin slab through roughing, reheat, finish rolling and batch, thereby produce hot rolling TRIP steel,
Wherein, finish rolling is performed as and makes that the rolling speed difference of single band steel is 15% or lower,
Finish rolling is performed as in the scope that the rolling temperature that makes in the finish to gauge frame falls into target temperature ± 20 that calculated by relational expression [910-225C-80Mn+15Si+10P] ℃, and
Carry out by this way and batch: the band steel after the finish rolling is cooled off with 25 ℃/s or higher speed on runoff table, batch at 350 ℃～470 ℃ then.
13. as any described method of claim 10 to the claim 12, wherein, carry out continuous casting with 4.5mpm or bigger casting speed.
14. as any described method of claim 10 to the claim 12, wherein, carries out roughing and make that the surface temperature of thin slab in the ingress of roughing mill is 950 ℃～1100 ℃, and the accumulation draft during roughing is 65%～90%.
15. as any described method of claim 10 to the claim 12, wherein, carry out reheat by this way: the band steel after the roughing is heated to 920 ℃～1150 ℃ or keep its heat.
Applications Claiming Priority (5)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| KR1020100111273A KR101245699B1 (en) | 2010-11-10 | 2010-11-10 | METHOD FOR MANUFACTURING TENSILE STRENGTH 590MPa CLASS HOT ROLLED TRIP STEEL WITH EXCELLENT VARIATION OF MECHANICAL PROPERTY |
| KR10-2010-0111273 | 2010-11-10 | ||
| KR10-2010-0111274 | 2010-11-10 | ||
| KR1020100111274A KR101245700B1 (en) | 2010-11-10 | 2010-11-10 | METHOD FOR MANUFACTURING TENSILE STRENGTH 590MPa CLASS COLD ROLLED TRIP STEEL WITH EXCELLENT VARIATION OF MECHANICAL PROPERTY |
| PCT/KR2011/008569 WO2012064129A2 (en) | 2010-11-10 | 2011-11-10 | Method for manufacturing high-strength cold-rolled/hot-rolled trip steel having a tensile strength of 590 mpa grade, superior workability, and low mechanical-property deviation |
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| Publication Number | Publication Date |
|---|---|
| CN103249847A true CN103249847A (en) | 2013-08-14 |
| CN103249847B CN103249847B (en) | 2015-06-10 |
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| CN201180058065.6A Expired - Fee Related CN103249847B (en) | 2010-11-10 | 2011-11-10 | Method for manufacturing high-strength cold-rolled/hot-rolled trip steel having a tensile strength of 590 mpa grade, superior workability, and low mechanical-property deviation |
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| Country | Link |
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| CN (1) | CN103249847B (en) |
| BR (1) | BR112013011409A2 (en) |
| WO (1) | WO2012064129A2 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107475627A (en) * | 2017-08-23 | 2017-12-15 | 武汉钢铁有限公司 | 600MPa levels analysis of producing hot rolled TRIP and manufacture method based on CSP flows |
| CN107488814A (en) * | 2017-08-23 | 2017-12-19 | 武汉钢铁有限公司 | 800MPa levels analysis of producing hot rolled TRIP and manufacture method based on CSP flows |
| CN107557692A (en) * | 2017-08-23 | 2018-01-09 | 武汉钢铁有限公司 | 1000MPa levels analysis of producing hot rolled TRIP and manufacture method based on CSP flows |
| CN107815593A (en) * | 2017-11-06 | 2018-03-20 | 东北大学 | A kind of economical high-aluminum low-silicon TRIP steel of automobile using and preparation method thereof |
| CN115404332A (en) * | 2022-09-20 | 2022-11-29 | 东北大学 | Ultrathin high-strength plate strip steel heat treatment temperature supplementing device and method |
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| CN107475627A (en) * | 2017-08-23 | 2017-12-15 | 武汉钢铁有限公司 | 600MPa levels analysis of producing hot rolled TRIP and manufacture method based on CSP flows |
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| CN115404332A (en) * | 2022-09-20 | 2022-11-29 | 东北大学 | Ultrathin high-strength plate strip steel heat treatment temperature supplementing device and method |
| CN115404332B (en) * | 2022-09-20 | 2024-01-16 | 东北大学 | Heat treatment temperature compensation device and method for ultrathin high-strength plate strip steel |
Also Published As
| Publication number | Publication date |
|---|---|
| WO2012064129A2 (en) | 2012-05-18 |
| CN103249847B (en) | 2015-06-10 |
| BR112013011409A2 (en) | 2016-08-02 |
| WO2012064129A3 (en) | 2012-07-12 |
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