WO2012064129A2 - 인장강도 590MPa급의 가공성 및 재질편차가 우수한 고강도 냉연/열연 TRIP강의 제조방법 - Google Patents
인장강도 590MPa급의 가공성 및 재질편차가 우수한 고강도 냉연/열연 TRIP강의 제조방법 Download PDFInfo
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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
-
- 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
-
- 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
-
- 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
Definitions
- the present invention relates to a method for manufacturing high strength cold rolled TRIP steel having excellent workability and material deviation of 590 MPa in tensile strength, and more particularly, high strength cold rolled steel and hot rolled TRIP having excellent elongation characteristics using thin slab playing method.
- a method of manufacturing steel is a method for manufacturing high strength cold rolled TRIP steel having excellent workability and material deviation of 590 MPa in tensile strength, and more particularly, high strength cold rolled steel and hot rolled TRIP having excellent elongation characteristics using thin slab playing method.
- TRIP steel is a residual austenite steel having a phase structure mixed with ferrite and bainite three phases by retaining austenite existing at high temperature at room temperature.
- the TRIP steel retains 5 ⁇ 20% of austenite at room temperature when appropriate heat-cooling heat treatment is added by adding austenite-reinforced elements C, Si, Mn, etc., and the austenite phase is metastable and martensite when deformed from the outside.
- the transformation occurs due to the machining process, unlike ordinary steel, it has a high work hardening index and an increase in necking resistance, thereby having excellent workability.
- the mini mill process for producing sheet material by the so-called thin slab performance which is a new steel process, which is recently attracting attention, is capable of producing a metamorphic tissue steel having good material deviation because the temperature deviation is small in the longitudinal direction of the strip. It is attracting attention as a process with potential.
- European Patent No. 0020314 US Patent Publication No. 2009-0214377, 2009-0151821, PCT Publication No. WO00 / 055381, etc.
- most of the patents focus on the cooling technology until rolling after rolling. It does not present the entire manufacturing technology of cold rolled TRIP steel with superior material properties using the characteristics of mini mill process.
- the present invention was developed in consideration of the state of the art, and the material deviation of the tensile strength 590MPa class to significantly reduce the material deviation in the width direction and the longitudinal direction of the strip while ensuring excellent workability using the thin slab playing method Its purpose is to provide a method for producing high strength cold rolled and hot rolled TRIP steel.
- the present invention provides a manufacturing method as follows.
- the finishing rolling step is such that the rolling speed difference in one strip is less than 15%
- the cooling heat treatment step is a slow cooling of the continuous annealing strip at a temperature of 620 ⁇ 690 °C at a cooling rate of 1 ⁇ 20 °C / s And, immediately after quenching at a cooling rate of 20 ⁇ 100 °C / s and consists of constant temperature transformation heat treatment in the temperature range of 310 ⁇ 420 °C.
- the finishing rolling step is such that the rolling temperature at the last rolling stand is within the range of ⁇ 20 °C of the target temperature calculated by the relation of [910-225C-65Mn + 15Si + 10P],
- the cold heat treatment step is a continuous annealing strip It is composed of slow cooling at a cooling rate of 1 to 20 °C / s at a temperature of 620 ⁇ 690 °C, immediately quenching at a cooling rate of 20 ⁇ 100 °C / s and then subjected to constant temperature heat treatment in the temperature range of 310 ⁇ 420 °C .
- the continuous annealing step is such that the continuous annealing temperature is within a range of ⁇ 15 ° C. of the target temperature calculated in the relation of [840-120C-45Mn + 25Si + 34P-45N -25Cu + 8Cr-30Ni].
- Annealed strips were slowly cooled to a cooling rate of 1 to 20 ° C / s at a temperature of 620 to 690 ° C, immediately quenched to a cooling rate of 20 to 100 ° C / s, and then subjected to constant temperature transformation at a temperature range of 310 to 420 ° C. It consists of doing.
- the finishing rolling step is such that the rolling speed difference in one strip is less than 15%, and the finishing rolling step is calculated by the relation of the rolling temperature at the final rolling stand is [910-225C-65Mn + 15Si + 10P] ⁇ 20 °C of the target temperature, the continuous annealing step is the continuous annealing temperature ⁇ 15 °C of the target temperature calculated in the relation of [840-120C-45Mn + 25Si + 34P-45N -25Cu + 8Cr-30Ni]
- the continuous annealing strip is slowly cooled at a cooling rate of 1 to 20 ° C./s at a temperature of 620 to 690 ° C., and then immediately quenched at a cooling rate of 20 to 100 ° C./s. It consists of constant temperature heat treatment in the temperature range of 310 ⁇ 420 °C.
- the continuous casting step is preferably a casting speed of 4.5 mpm or more.
- the surface temperature of the thin slab at the inlet side of the rough mill is preferably 950 to 1100 ° C.
- the cumulative rolling rate during the rough rolling is 65 to 90%.
- the heating step preferably heats or heats the roughly rolled strip at 920 to 1150 ° C.
- the winding step it is preferable to wind the finish rolled strip at 480 to 680 ° C.
- the finish rolling step is such that the rolling speed difference in one strip is 15% or less, and the winding step is after cooling the finish rolled strip at a cooling rate of at least 25 °C / s at a runout table of 350 ⁇ 470 °C It consists of winding at temperature.
- Another manufacturing method by weight% C: 0.06 ⁇ 0.20%, Si: 0.8 ⁇ 2.0%, Mn: 1.2 ⁇ 2.2%, P: 0.001 ⁇ 0.1%, S: 0.001 ⁇ 0.02%, Al: 0.01 ⁇ 2.0%, N: 0.001 ⁇ 0.02%, total tramp element (Cu + Ni + Sn + Pb): 0.18% or less, Ti: 0.001 ⁇ 0.1%, Nb: 0.001 ⁇ 0.1%, V: 0.001 ⁇ 0.1% At least one of them is added, and the steel composed of the remaining Fe and other unavoidable impurities is continuously cast into thin slabs having a thickness of 30 to 150 mm, and the thin slabs are subjected to hot rolling, reheating, finishing rolling, and winding to obtain hot rolled TRIP steel.
- the manufacturing method by weight% C: 0.06 ⁇ 0.20%, Si: 0.8 ⁇ 2.0%, Mn: 1.2 ⁇ 2.2%, P: 0.001 ⁇ 0.1%, S: 0.00
- the finishing rolling step is such that the rolling temperature at the last rolling stand is in the range of ⁇ 20 °C of the target temperature calculated by the relation of [910-225C-80Mn + 15Si + 10P], the winding step is to take the finish rolled strip It consists of cooling at a cooling rate of 25 ° C./s or more at the runout table and then winding at a temperature of 350 to 470 ° C.
- Another manufacturing method by weight% C: 0.06 ⁇ 0.20%, Si: 0.8 ⁇ 2.0%, Mn: 1.2 ⁇ 2.2%, P: 0.001 ⁇ 0.1%, S: 0.001 ⁇ 0.02%, Al: 0.01 to 2.0%, N: 0.001 to 0.02%, total tramp element (Cu + Ni + Sn + Pb): 0.18% or less, Ti: 0.001 to 0.1%, Nb: 0.001 to 0.1%, V: 0.001 to 0.1 At least one of% is added, and the steel composed of the remaining Fe and other unavoidable impurities is continuously cast into thin slabs with a thickness of 30 to 150 mm, and the thin slabs are subjected to hot rolling, reheating, finishing rolling and winding to obtain hot rolled TRIP steel.
- the finishing rolling step is such that the rolling speed difference in one strip is less than 15%, and the finishing rolling step is calculated by the relation of the rolling temperature at the last rolling stand is [910-225C-80Mn + 15Si + 10P]
- the winding step is to be in the range of ⁇ 20 °C of the target temperature, the winding step consists of cooling the finish rolled strip at a cooling rate of 25 °C / s or more in the runout table and then wound at a temperature of 350 ⁇ 470 °C.
- the above manufacturing method is preferably a casting speed of 4.5 mpm or more in the continuous casting step.
- the thin slab surface temperature at the entrance side of the rough rolling mill is 950 to 1100 ° C.
- the cumulative rolling reduction rate at the rough rolling is 65 to 90%.
- the heating step it is preferable to heat or heat the roughly rolled strip at 920 to 1150 ° C.
- the thin slab playing method can omit the reheating process in the existing mill, thereby saving energy and improving productivity.
- the thin slab playing method can be used to melt the scrap steel, such as scrap in the electric furnace can increase the recycling of resources.
- FIG. 1 is a schematic diagram illustrating a minimill process of the present invention.
- heating means 40 coil box
- the mini mill process according to the present invention will be briefly described with reference to FIG.
- the hot rolled strip produced by this mini-mill process is manufactured through a known cold rolling process (pickling, cold rolling, continuous annealing, cold heat treatment), and thus the description of the cold rolling process will be omitted.
- a thin slab (a) having a thickness of 30 ⁇ 150mm This is called thin slab in comparison with slabs of 200 mm or more produced by continuous casting machines of conventional mills. Since a slab of 200 mm or more is completely cooled in a yard or the like, it has to be sufficiently reheated to a surface temperature of 1100 ° C. or more in a reheating furnace before hot rolling. On the contrary, since the thin slab is immediately transferred to the roughing mill 20 without passing through the reheating furnace, the heat slab can be used as it is, thereby reducing energy and greatly improving productivity.
- the temperature of the strip lowered in the process is compensated by the heating means 30, and then the heated hot rolled strip b is finished in the finishing mill 50.
- Rolled to the desired final thickness cooled through ROT [Run Out Table 60] (hereinafter referred to as "runout table"), and then finally wound in a constant temperature in the winder 70 to produce a hot rolled steel sheet of the desired material do.
- the coil box 40 may be installed in front of the finish rolling mill 50 so as to be configured to firstly wind the hot rolled strip b passed through the induction heater 30. have.
- a true continuous rolling process without using the coil box 40 has been developed.
- High-strength cold-rolled TRIP steel of the present invention produced through the above-described mini-mill and cold rolling process, C: 0.05 ⁇ 0.20%, Si: 0.8 ⁇ 2.0%, Mn: 1.2 ⁇ 2.2%, P: 0.001 ⁇ 0.1%, S: 0.001 to 0.02%, Al: 0.01 to 2.0%, N: 0.001 to 0.02%, Sb: 0.005 to 0.1%, total tramp element (Cu + Cr + Ni + Sn + Pb): 0.18% or less and the remaining Fe and It is composed of other unavoidable impurities.
- the function of each element and its content range are briefly described.
- C is an element that determines the untransformed austenite fraction in the annealing temperature range, and also acts to improve ductility by stabilizing austenite by diffusing into austenite during constant temperature transformation heat treatment. If the content is less than 0.05%, the fraction of the retained austenite becomes small, so that the material targeted in the present invention cannot be secured, whereas if the content is less than 0.20%, the weldability is increased. Therefore, the content of C is preferably limited to 0.05 to 0.20%.
- the Si is an element that stabilizes austenite by increasing the strength of the steel sheet by solid solution strengthening and suppressing the precipitation of cementite to promote C concentration into unmodified austenite. If the content is less than 0.8%, it is difficult to secure the above effects, while if the content exceeds 2.0%, the paintability, corrosion resistance and weldability are likely to be lowered. Therefore, the content of Si is preferably limited to 0.8 to 2.0%.
- the Mn is an austenite-forming element and has an effect of slowing the diffusion rate of carbon together with a solid solution strengthening effect and serves to suppress transformation during the cooling process. If the content is less than 1.2%, it is difficult to secure the amount of retained austenite, and it is difficult to secure the target strength of the present invention. If the content is more than 2.2%, the diffusion of C is insufficient during the holding time of the austenite. It would rather hinder stability. Therefore, the content of Mn is preferably limited to 1.2 to 2.2%.
- the P is an element having the effect of reinforcing the steel sheet by solid solution strengthening and promoting C concentration to austenite during constant temperature transformation heat treatment when added with Si. If the content is less than 0.001%, not only the effect may not be secured, but also increase the manufacturing cost, while if the content exceeds 0.1%, the risk of brittleness may increase with deterioration of the viscosity of the viscosity. Therefore, the content of P is preferably limited to 0.001 to 0.1%.
- S is an impurity element in steel that causes segregation in the slab and inhibits the ductility and weldability of the steel sheet. It is difficult to manufacture the content to less than 0.001%, and exceeding 0.02% increases the risk of problems such as slab segregation, as well as the possibility of inhibiting the ductility and weldability of the steel sheet. Therefore, the content of S is preferably limited to 0.001 to 0.02%.
- the acid soluble Al is an element effective in stabilizing austenite by combining with oxygen in steel and deoxidizing and distributing carbon in ferrite to austenite such as Si. If the content is less than 0.01%, the effect cannot be secured, while if the content exceeds 2.0%, the effect not only saturates but also increases the inclusions with the manufacturing cost. Therefore, the content of acid soluble Al is preferably limited to 0.01 ⁇ 2.0%.
- N is an element that effectively acts to stabilize austenite. If the content is less than 0.001%, it is difficult to expect the effect, and if the content is more than 0.02%, the effect may be saturated while increasing the weldability and manufacturing cost. Therefore, the content of N is preferably limited to 0.001 ⁇ 0.02%.
- the Sb is an element having an excellent effect of suppressing surface thickening of oxides to lower surface defects and suppressing coarsening of surface concentrates. If the content is less than 0.005%, it is difficult to secure the above effects. If the content is more than 0.1%, the effects may be saturated while causing problems such as manufacturing cost and workability deterioration. Therefore, the content of Sb is preferably limited to 0.005 ⁇ 0.1%.
- the tramp element (Cu + Cr + Ni + Sn + Pb) is a kind of impurity element derived from scrap used as a raw material in the steelmaking process. If the content exceeds 0.18%, it causes a surface crack of the thin slab cast slab, it is preferable to limit the content to 0.18% or less.
- the present invention is composed of Fe and other unavoidable impurities in addition to the above components.
- the present invention is a mini-mill hot rolling process consisting of continuous casting, rough rolling, heating, finishing rolling, cooling and winding steps, and a cold rolling process consisting of pickling, cold rolling, continuous annealing, and cold heat treatment steps.
- the characteristic technical configuration of the present invention is to control the operating conditions of each step to produce a high-strength cold rolled TRIP steel excellent in the material deviation of the target.
- the casting speed is preferably at least 4.5 mpm.
- steel with a tensile strength of 590 MPa or more has a higher content of elements added for the purpose of securing strength of C, Mn, Si, etc. in steel compared to soft products, so that the slower the casting speed, the higher the risk of segregation from the cast steel.
- the stone is generated, it is difficult to secure the strength, and the speed is limited to 4.5mpm or more because there is a high risk of material deviation in the width direction or the length direction.
- the continuous cast thin slab is roughly rolled in a rough rolling mill consisting of two to four stands.
- the thin slab surface temperature at the entrance side of the rough mill is set to 950 to 1100 ° C., and that the cumulative reduction rate at the time of rough rolling is 65 to 90%.
- the rough rolling load increases not only significantly but also increases the risk of edge cracking, and if it exceeds 1100 °C, the arithmetic scale may occur. Limit to 950 ⁇ 1100 °C.
- the cumulative reduction ratio during rough rolling plays an important role in obtaining a product having a uniform material targeted in the present invention.
- the higher the rolling reduction rate during rough rolling the more uniform the microscopic distribution of elements such as Mn, Si, and Al, which are important for manufacturing TRIP steel, and the smaller the temperature gradient in the width and thickness directions of the strip.
- the cumulative reduction ratio is less than 65%, the above effects are not sufficiently exhibited.
- the cumulative reduction ratio is greater than 90%, the rolling deformation resistance is greatly increased to increase the manufacturing cost, so that the cumulative reduction ratio is rolled to 65 to 90%. It is desirable to.
- the heating step it is preferable to heat or heat the roughly rolled strip to a temperature of 920 to 1150 ° C.
- the surface temperature of the roughly rolled strip is less than 920 ° C., the rolling deformation resistance is greatly increased, and if it exceeds 1150 ° C., not only the energy cost for the temperature rise is increased but also the tendency of surface scale defects is generated. It is desirable to limit the temperature to 920-1150 ⁇ ⁇ .
- the finishing rolling step is preferably such that the rolling speed difference in one strip is 15% or less.
- 590MPa grade high-strength cold-rolled TRIP steel aimed at the present invention is very likely to change the material properties according to the rolling speed during finish rolling because the formation of the transformation structure as a reinforcing mechanism.
- the difference in rolling speed exceeds 15% in a finishing mill consisting of a plurality of stands, it becomes difficult to obtain a uniform cooling rate and a target winding temperature in a subsequent run-out table, and thus the material in the width or length direction of the strip. It causes a large deviation.
- the finishing rolling step is preferably such that the rolling temperature at the last rolling stand is within the range of ⁇ 20 °C of the target temperature calculated by the relation of [910-225C-65Mn + 15Si + 10P].
- the target temperature calculated by the relation of [910-225C-65Mn + 15Si + 10P].
- the finish rolling temperature is between Ar 1 and Ar 3 transformation points by utilizing the characteristics that the temperature management of the strip is easy as compared with the existing hot rolling process.
- the temperature is changed by the component and rolling in the range of ⁇ 20 °C of the target temperature calculated by the relational formula [910-225C-65Mn + 15Si + 10P] by repeated experiment It was confirmed that can be carried out.
- the finish rolled strip it is preferable to wind the finish rolled strip at 480 to 680 ° C. If the hot rolled coil temperature is less than 480 °C, the hot rolled strength is greatly increased, which is a problem for cold rolling property, and if the hot rolled coil temperature exceeds 680 °C, the risk of hot rolled duckbill coil is greatly increased, limiting the temperature to 480 ⁇ 680 °C It is preferable.
- the pickled strip is preferably rolled at a reduction ratio of 40 to 75%. If the reduction rate is less than 40%, there is a risk that recrystallization does not occur during annealing. If the reduction rate exceeds 75%, the rolling deformation resistance is greatly increased, which makes rolling difficult. Therefore, it is preferable to limit the reduction rate to 40 to 75%. .
- the continuous annealing step is preferably such that the continuous annealing temperature is within the range of ⁇ 15 °C of the target temperature calculated in the relation of [840-120C-45Mn + 25Si + 34P-45N -25Cu + 8Cr-30Ni].
- TRIP steel is advantageous in securing the material by annealing heat treatment in the region where austenite and ferrite coexist during the annealing process during manufacturing.
- the relational expressions above are formulated in order to obtain better materials by empirically formulating coexistence regions that change depending on not only main alloying elements such as C, Mn, Si, but also components such as tramp elements.
- the austenite fraction is too small or there is a risk of unrecrystallization. If the annealing heat treatment exceeds 15 °C than the target temperature, the austenite fraction is too high. This results in a dilution of the concentration of C in the solution, which leads to a decrease in the fraction of retained austenite in the final tissue and to an increase in the martensite or bainite fraction, as well as to problems with strip flowability due to high temperatures. It is preferable to limit to the above conditions.
- the cooling heat treatment step is a slow cooling of the continuous annealing strip at a cooling rate of 1 ⁇ 20 °C / s at a temperature of 620 ⁇ 690 °C, immediately quenched at a cooling rate of 20 ⁇ 100 °C / s 310 ⁇ It is preferable to carry out constant temperature transformation heat processing in the temperature range of 420 degreeC.
- cooling to a temperature of less than 620 °C increases the risk of precipitation of carbide, if the temperature exceeds 690 °C austenite stabilization is not effective.
- the rate is less than 1 °C / s there is a risk that the productivity is greatly reduced, if the rate exceeds 20 °C / s during the cooling process C diffusion into austenite is insufficient.
- the temperature is lower than 310 °C during constant temperature transformation heat treatment, the C concentration to austenite is insufficient, and if the temperature exceeds 420 °C, the risk of precipitation of cementite, etc. is greatly increased, resulting in lowered ductility. It is preferable to limit to the conditions.
- each material (tensile strength) after the production of hot-rolled strip in the process conditions such as slab thickness, circumferential speed, slab surface temperature, rolling speed difference, finish rolling temperature and annealing temperature of Table 2 , Elongation and material deviation) and the presence or absence of surface scale are shown in Table 2.
- steel grades 1 to 5 were manufactured by hot rolling strips by thin slab playing method (slab thickness: 84 mm), and steel grades 6 to 7 (slab thickness: 230 mm) were manufactured by hot rolled strip under conditions of conventional mill.
- the slab surface temperature means the surface temperature measured just before rough rolling.
- the rolling speed difference is expressed as a percentage obtained by dividing the difference between the maximum and minimum sheet speeds in one strip by the average sheet speed in the final finishing rolling, and the smaller the value, the smaller the variation in the rolling speed.
- the finish rolling temperature indicates whether rolling was carried out to be within ⁇ 20 ° C. of the target temperature determined by the calculated value of Equation 1, and Comparative steels 4, 7, and 8 were used at temperatures corresponding to the single phase region immediately above the Ar 3 transformation point. Rolling progressed.
- the heating temperatures of the strip after rough rolling were all applied at 1075 ° C., and the reheating temperatures were all applied at 1200 ° C. under the conditions of steel grades 6 to 7, and the final hot rolled strips were applied.
- the thickness was made equal to 3.2 mm.
- the hot rolled strip was prepared with a cold rolled strip having a cold rolling rate of 56.3% and 1.4 mm, and each cold rolled strip was subjected to recrystallization annealing at the annealing temperature of Table 2 and then cooled to 650 at a cooling rate of 7 ° C / s. Slow cooling to °C, followed by cooling at a cooling rate of about 70 °C / s was subjected to constant temperature transformation heat treatment at a temperature of 380 ⁇ 410 °C.
- Equation 1 [910-225C-65Mn + 15Si + 10P]
- Equation 2 [840-120C-45Mn + 25Si + 34P-45N-25Cu + 8Cr-30Ni]
- Tensile strength and elongation of Table 2 are the values measured by collecting the JIS No. 5 specimen in the rolling perpendicular direction at the point of width w / 4. Elongation is the percentage of tensile strain until fracture of the tensile specimen occurs, and material deviation is the maximum value minus the minimum value of the material measured in the longitudinal and width directions of the coil.
- TS x EI tensile strength x elongation
- TS x EI is an index indicating the superiority of the elongation characteristics of high-strength steel in which the elongation decreases as the strength increases, which means that the higher the value, the higher the tensile strength and the elongation.
- the composition of the high-strength hot-rolled TRIP steel of the present invention by weight% C: 0.06 ⁇ 0.20%, Si: 0.8 ⁇ 2.0%, Mn: 1.2 ⁇ 2.2%, P: 0.001 ⁇ 0.1%, S: 0.001 ⁇ 0.02%, Al : 0.01 to 2.0%, N: 0.001 to 0.02%, total tramp element (Cu + Ni + Sn + Pb): 0.18% or less, Ti: 0.001 to 0.1%, Nb: 0.001 to 0.1%, V: 0.001 to At least one of 0.1% is added and composed of the remaining Fe and other unavoidable impurities.
- the function of each element and its content range are briefly described.
- the C is a component that serves to improve the ductility by increasing the amount of austenite remaining at room temperature by stabilizing austenite. If the content is less than 0.06%, the austenite fraction is small, the target material of the present invention can not be secured, while if the content is more than 0.20%, the weldability is likely to decrease. Therefore, the content of C is preferably limited to 0.06 to 0.20%.
- the Si is an element that stabilizes austenite by increasing the strength of the steel sheet by solid solution strengthening and suppressing the precipitation of cementite to promote C concentration into unmodified austenite. If the content is less than 0.8%, it is difficult to secure the above effects, while if the content exceeds 2.0%, the paintability, corrosion resistance and weldability are likely to be lowered. Therefore, the content of Si is preferably limited to 0.8 to 2.0%.
- the Mn has a solid solution strengthening effect as an austenite stabilizing element and serves to suppress transformation during the cooling process. If the content is less than 1.2%, it is difficult to secure the amount of residual austenite, and it is difficult to secure the strength targeted by the present invention. If the content exceeds 2.2%, problems such as hot rolling property are likely to occur. Therefore, the content of Mn is preferably limited to 1.2 to 2.2%.
- the P is an element that strengthens the steel sheet by solid solution strengthening and promotes C concentration to austenite when it is added with Si. If the content is less than 0.001%, not only the effect is not secured, but the manufacturing cost is increased, while if the content exceeds 0.1%, the risk of brittleness increases with deterioration of the viscosity of the viscosity. Therefore, the content of P is preferably limited to 0.001 to 0.1%.
- S is an impurity element in steel that causes segregation in the slab and inhibits ductility and weldability of the steel sheet. It is difficult to manufacture the content to less than 0.001%, and when it exceeds 0.02%, not only increases the risk of slab segregation and the like, but also increases the ductility and weldability of the steel sheet. Therefore, the content of S is preferably limited to 0.001 to 0.02%.
- the acid soluble Al is an element effective in stabilizing austenite by combining with oxygen in steel and deoxidizing and distributing carbon in ferrite to austenite such as Si. If the content is less than 0.01%, the effect cannot be secured, whereas if the content exceeds 2.0%, the effect is not only saturated but also increases the inclusions with the manufacturing cost. Therefore, the content of acid soluble Al is preferably limited to 0.01 to 2.0%.
- N is an element that effectively acts to stabilize austenite.
- the content of N is less than 0.001%, it is difficult to expect the above effects.
- the content of N exceeds 0.02%, the above effects are saturated while weldability is lowered and manufacturing costs are increased. Therefore, the content of N is preferably limited to 0.001 ⁇ 0.02%.
- the tramp element (Cu + Ni + Sn + Pb) is a kind of impurity element derived from scrap used as a raw material in the steelmaking process. If the content exceeds 0.18%, it causes the surface crack of the slab cast slab. It is desirable to limit the content to 0.18% or less.
- At least one of Ti, Nb, and V may be added to the steel formed as described above.
- the elements are not an element that has a decisive influence on securing the basic physical properties of the high strength hot rolled TRIP steel aimed at in the present invention, it is preferable to add one or more kinds for fine control of tensile strength, yield strength and surface quality of the product.
- Ti, Nb and V are effective elements to increase the yield strength and refine the grain size of the steel sheet.
- the content of the elements is less than 0.001%, it is difficult to secure such an effect.
- the content exceeds 0.1%, ferrite ductility may be lowered due to an increase in manufacturing cost and excessive precipitates. Therefore, it is desirable to limit the content to 0.001 to 0.1%.
- the present invention is composed of Fe and other unavoidable impurities in addition to the above components.
- the mini-mill process is composed of continuous casting, rough rolling, heating, finishing rolling, cooling and winding stages
- the characteristic technical configuration of the present invention is to control the operating conditions of each of the above steps newly It is to produce high strength hot rolled TRIP steel with excellent phosphorous material deviation.
- the casting speed is preferably at least 4.5mpm.
- steel with a tensile strength of 590 MPa or more has a high content of elements added in order to secure the strength of C, Mn, Si, etc. in steel, so that the slower the casting speed, the greater the risk of segregation from the cast steel.
- the speed is limited to 4.5mpm or more because there is a high risk of material deviation in the width direction or the length direction.
- the continuous cast thin slab is roughly rolled in a rough rolling mill consisting of two to four stands.
- the thin slab surface temperature at the entrance side of the rough mill is set to 950 to 1100 ° C., and that the cumulative reduction rate at the time of rough rolling is 65 to 90%.
- the rough rolling load increases not only significantly but also increases the risk of edge cracking, and if it exceeds 1100 °C, the arithmetic scale may occur. Limit to 950 ⁇ 1100 °C.
- the cumulative reduction ratio during rough rolling plays an important role in obtaining a product having a uniform material targeted in the present invention.
- the higher the rolling reduction rate during rough rolling the more uniform the microscopic distribution of elements such as Mn, Si, and Al, which are important for manufacturing TRIP steel, and the smaller the temperature gradient in the width and thickness directions of the strip.
- the cumulative reduction ratio is less than 65%, the above effects are not sufficiently exhibited.
- the cumulative reduction ratio is greater than 90%, the rolling deformation resistance is greatly increased to increase the manufacturing cost, so that the cumulative reduction ratio is rolled to 65 to 90%. It is desirable to.
- the heating step it is preferable to heat and heat the roughly rolled strip to a temperature of 920 to 1150 ° C.
- the surface temperature of the roughly rolled strip is less than 920 ° C., the rolling deformation resistance is greatly increased, and if it exceeds 1100 ° C., not only the energy cost for the temperature rise is increased but also the tendency of surface scale defects is generated. It is desirable to limit the temperature to 920-1150 ⁇ ⁇ .
- the finishing rolling step is preferably such that the rolling speed difference in one strip is 15% or less.
- 590MPa class high-strength hot rolled TRIP steel for the purpose of the present invention is very likely to change the material properties according to the rolling speed during finish rolling because the formation of the transformation structure as a reinforcing mechanism.
- the difference in rolling speed exceeds 15% in the finishing rolling mill consisting of a plurality of stands, it becomes difficult to obtain a uniform cooling rate and a target winding temperature in a subsequent runout table, and thus the material in the width direction or the length direction of the strip. It causes a large deviation.
- the finishing rolling step is preferably such that the rolling temperature at the last rolling stand is within the range of ⁇ 20 °C of the target temperature calculated by the relation of [910-225C-80Mn + 15Si + 10P].
- the target temperature calculated by the relation of [910-225C-80Mn + 15Si + 10P].
- the finish rolling temperature is between Ar 1 and Ar 3 transformation points by utilizing the characteristics that the temperature management of the strip is easy as compared with the existing hot rolling process.
- the temperature is changed by the component and rolling in the range of ⁇ 20 ° C of the target temperature calculated by the relational formula [910-225C-80Mn + 15Si + 10P] by repeated experiments It was confirmed that can be carried out.
- the finish rolled strip is preferably cooled at a temperature of 350 ⁇ 470 °C after cooling at a cooling rate of 25 °C / s or more in the runout table. If the cooling rate in the runout table is less than 25 ° C / s, austenite stabilizing elements such as C, Mn, etc. are precipitated to aerolite in austenite grains, so that the thickening effect is lowered.
- the hot rolling temperature is less than 350 ° C.
- martensite is formed and the strength is greatly increased, but the elongation is high.
- the temperature exceeds 470 ° C., cementite is precipitated in the steel to form residual austenite. Since the risk of inhibition is greatly increased, the hot rolling temperature is limited to 380 to 490 ° C.
- finish rolling step and the winding step described above are characteristic technical configurations of the present invention. By combining two or more of these, it is possible to produce high strength hot rolled TRIP steel having excellent material deviation of tensile strength 590MPa class required by the present invention.
- steel grades 1 to 6 is a case where a hot rolled strip is manufactured by a thin slab playing method (slab thickness: 84 mm), and steel grades 7 to 8 (slab thickness: 230 mm) are a case where a hot rolled strip is manufactured under conditions of a conventional mill.
- the slab surface temperature means the surface temperature measured just before rough rolling.
- the rough rolling reduction rate refers to a value obtained by dividing the difference between the slab thickness (84mm) at the entrance of the rough rolling mill and the strip thickness (mm) at the exit of the rough rolling mill by the slab thickness as a percentage.
- the rolling speed difference is expressed as a percentage obtained by dividing the difference between the maximum and minimum sheet speeds in one strip by the average sheet speed in the final finishing rolling, and the smaller the value, the smaller the variation in the rolling speed.
- the finish rolling temperature indicates whether the rolling was carried out to be within ⁇ 20 ° C of the target temperature determined by the calculated value of Equation 3, and Comparative steels 5, 8, and 9 were used at temperatures corresponding to the single phase region directly above the Ar 3 transformation point. Rolling progressed.
- the heating temperatures of the strips after rough rolling were all applied at 1060 ° C., and the reheating temperatures were all applied at 1200 ° C. under the conditions of steel grades 7 to 8.
- the cooling rate on the runout table for all steels was wound up to about 50 ° C./s and the final thickness of the hot rolled strip was made equal to 3.0 mm.
- Equation 3 [910-225C-80Mn-15Si + 10P]
- Tensile strength and elongation of Table 4 are the values taken by measuring the JIS No. 5 specimen in the rolling perpendicular direction at the point of width w / 4. Elongation is the percentage of tensile strain until fracture of the tensile specimen occurs, and material deviation is the maximum value minus the minimum value of the material measured in the longitudinal and width directions of the coil.
- TS x EI tensile strength x elongation
- TS x EI is an index indicating the superiority of the elongation characteristics of high-strength steel in which the elongation decreases as the strength increases, which means that the higher the value, the higher the tensile strength and the elongation.
Abstract
Description
강종 | C | Si | Mn | P | S | Al | N | Sb | 트램프 원소 | 비고 | |||
Cu | Cr | Ni | Sn | ||||||||||
1 | 0.08 | 1.5 | 1.6 | 0.012 | 0.003 | 0.03 | 0.006 | 0.02 | 0.05 | 0.03 | 0.03 | 0.01 | 박 슬라브 |
2 | 0.06 | 1.8 | 1.5 | 0.015 | 0.003 | 0.02 | 0.010 | 0.02 | 0.06 | 0.03 | 0.02 | 0.01 | |
3 | 0.06 | 1.5 | 1.9 | 0.020 | 0.003 | 0.04 | 0.010 | 0.02 | 0.05 | 0.02 | 0.03 | 0.01 | |
4 | 0.07 | 1.0 | 1.6 | 0.013 | 0.003 | 0.40 | 0.006 | 0.01 | 0.06 | 0.03 | 0.03 | 0.02 | |
5 | 0.18 | 1.4 | 1.6 | 0.025 | 0.003 | 0.03 | 0.007 | 0.02 | 0.05 | 0.03 | 0.02 | 0.01 | |
6 | 0.08 | 1.5 | 1.6 | 0.012 | 0.003 | 0.03 | 0.006 | 0.02 | - | - | - | - | 기존밀 |
7 | 0.09 | 1.2 | 1.7 | 0.025 | 0.003 | 0.03 | 0.004 | 0.02 | - | - | - | - |
구분 | 강종 | 슬라브두께(mm) | 주속(mpm) | 슬라브표면온도(℃) | 압연속도차(%) | 마무리압연온도(℃) | 식1계산값 | 소둔온도(℃) | 식2계산값 | 인장강도(MPa) | 연신율(%) | 재질편차(△TS,Mpa) | TS×EI | 산수형스케일발생 |
발명강1 | 1 | 84 | 6.5 | 1023 | 5 | 810 | 811 | 800 | 794 | 642 | 32.5 | 10 | 20,865 | × |
발명강2 | 2 | 84 | 6.5 | 1015 | 5 | 820 | 826 | 810 | 809 | 617 | 32.9 | 13 | 20,299 | × |
발명강3 | 3 | 84 | 6.5 | 1021 | 5 | 800 | 796 | 780 | 783 | 641 | 33.1 | 16 | 21,217 | × |
발명강4 | 4 | 84 | 6.5 | 1002 | 5 | 800 | 805 | 780 | 783 | 625 | 34.0 | 8 | 21,250 | × |
발명강5 | 5 | 84 | 6.5 | 1028 | 5 | 790 | 787 | 780 | 780 | 615 | 32.4 | 16 | 19,926 | × |
비교강1 | 1 | 84 | 4.2 | 1026 | 5 | 810 | 811 | 800 | 794 | 625 | 33.0 | 30 | 20,625 | × |
비교강2 | 2 | 84 | 6.5 | 1125 | 5 | 820 | 826 | 810 | 809 | 635 | 32.3 | 18 | 20,511 | ○ |
비교강3 | 3 | 84 | 6.5 | 987 | 25 | 800 | 796 | 780 | 783 | 630 | 30.5 | 45 | 19,215 | × |
비교강4 | 4 | 84 | 6.5 | 1032 | 5 | 900 | 805 | 780 | 783 | 628 | 29.1 | 18 | 18,275 | × |
비교강5 | 5 | 84 | 6.5 | 1011 | 5 | 790 | 787 | 825 | 780 | 560 | 27.0 | 17 | 15,120 | × |
비교강6 | 5 | 84 | 6.5 | 996 | 5 | 790 | 787 | 770 | 780 | 690 | 24.5 | 24 | 16,905 | × |
비교강7 | 6 | 230 | 1.0 | 1084 | 30 | 910 | 811 | 800 | - | 642 | 31.1 | 55 | 19,966 | × |
비교강8 | 7 | 230 | 1.0 | 1080 | 30 | 910 | 798 | 800 | - | 625 | 32.2 | 62 | 20,125 | × |
강종 | C | Si | Mn | P | S | Al | N | Ti | Nb | V | 식1 계산식 | 비고 |
1 | 0.06 | 0.8 | 1.3 | 0.035 | 0.003 | 0.045 | 0.007 | - | - | - | 824 | 박 슬라브 |
2 | 0.07 | 0.8 | 1.35 | 0.015 | 0.003 | 0.42 | 0.007 | - | 0.01 | - | 819 | |
3 | 0.06 | 0.8 | 1.3 | 0.035 | 0.003 | 0.21 | 0.008 | 0.015 | - | - | 824 | |
4 | 0.18 | 1.7 | 1.4 | 0.013 | 0.003 | 0.03 | 0.007 | - | - | - | 804 | |
5 | 0.17 | 1.7 | 1.9 | 0.013 | 0.003 | 0.04 | 0.007 | - | 0.015 | - | 774 | |
6 | 0.18 | 1.6 | 1.7 | 0.014 | 0.003 | 0.03 | 0.008 | - | - | 0.01 | 783 | |
7 | 0.10 | 1.0 | 1.21 | 0.020 | 0.004 | 0.04 | 0.004 | - | - | - | 824 | 기존밀 |
8 | 0.10 | 1.6 | 1.7 | 0.015 | 0.003 | 0.03 | 0.003 | - | 0.015 | - | 801 |
구분 | 강종 | 슬라브두께(mm) | 주속(mpm) | 슬라브표면온도(℃) | 조압연시누적압하율(%) | 압연속도차(%) | 마무리압연온도(℃) | 식1계산값 | 권취온도(℃) | 인장강도(MPa) | 연신율(%) | 재질편차(△TS,Mpa) | TS×EI | 산수형스케일발생 |
발명강1 | 1 | 84 | 6.2 | 1015 | 76.2 | 7 | 820 | 824 | 420 | 617 | 31 | 20 | 19,127 | × |
발명강2 | 2 | 84 | 6.2 | 1023 | 76.2 | 7 | 820 | 819 | 420 | 620 | 31 | 15 | 19,220 | × |
발명강3 | 3 | 84 | 6.2 | 1045 | 76.2 | 7 | 820 | 824 | 420 | 625 | 31 | 13 | 19,375 | × |
발명강4 | 3 | 84 | 6.2 | 1028 | 82.1 | 9 | 820 | 824 | 420 | 602 | 32 | 17 | 19,264 | × |
발명강5 | 4 | 84 | 6.2 | 1022 | 75.2 | 7 | 800 | 804 | 420 | 665 | 21 | 15 | 13,965 | × |
발명강6 | 5 | 84 | 6.2 | 998 | 75.2 | 7 | 770 | 774 | 420 | 640 | 31 | 15 | 19,840 | × |
발명강7 | 6 | 84 | 6.2 | 1005 | 75.2 | 7 | 770 | 783 | 420 | 605 | 32 | 14 | 19,360 | × |
비교강1 | 1 | 84 | 4.1 | 1025 | 76.2 | 7 | 820 | 824 | 420 | 615 | 29 | 31 | 17,835 | × |
비교강2 | 2 | 84 | 6.2 | 1115 | 76.2 | 7 | 820 | 819 | 420 | 605 | 30 | 41 | 18,150 | ○ |
비교강3 | 3 | 84 | 6.2 | 1025 | 63.1 | 5 | 820 | 824 | 420 | 625 | 27 | 38 | 16,875 | × |
비교강4 | 4 | 84 | 6.2 | 1015 | 75.2 | 23 | 800 | 804 | 420 | 635 | 29 | 45 | 18,415 | × |
비교강5 | 5 | 84 | 6.2 | 1023 | 75.2 | 7 | 870 | 774 | 420 | 615 | 27 | 23 | 16,605 | × |
비교강6 | 6 | 84 | 6.2 | 978 | 75.2 | 7 | 770 | 783 | 320 | 689 | 20 | 35 | 13,780 | × |
비교강7 | 6 | 84 | 6.2 | 1025 | 75.2 | 7 | 770 | 783 | 510 | 581 | 25 | 28 | 14,525 | × |
비교강8 | 7 | 230 | 1.0 | 1084 | - | 30 | 870 | 824 | 420 | 610 | 27 | 70 | 16,470 | × |
비교강9 | 8 | 230 | 1.0 | 1080 | - | 30 | 870 | 801 | 420 | 605 | 27 | 64 | 16,335 | × |
Claims (15)
- 중량%로 C: 0.05 ~ 0.20%, Si: 0.8 ~ 2.0%, Mn: 1.2 ~ 2.2%, P: 0.001 ~ 0.1%, S: 0.001 ~ 0.02%, Al: 0.01 ~ 2.0%, N: 0.001 ~ 0.02%, Sb: 0.005 ~ 0.1%, 총 트램프원소(Cu+Cr+Ni+Sn+Pb): 0.18%이하 및 나머지 Fe 및 기타 불가피한 불순물로 조성된 강을 두께 30 ~ 150mm의 박 슬라브로 연속주조하고, 이 박 슬라브를 조압연, 가열, 마무리 압연 및 권취 단계를 통해 열연 스트립을 제조하며, 이 열연 스트립을 산세, 냉간압연, 연속소둔 및 냉각 열처리 단계를 통해 냉연 TRIP강을 제조하는 방법에 있어서,상기 마무리 압연 단계는 하나의 스트립 내에서의 압연 속도차가 15% 이하가 되도록 하고,상기 냉각 열처리 단계는 연속소둔 처리된 스트립을 620 ~ 690℃의 온도로 1 ~ 20℃/s의 냉각속도로 서냉하고, 곧바로 20 ~ 100℃/s의 냉각속도로 급냉한 후 310 ~ 420℃의 온도 범위에서 항온변태 열처리하는 것을 특징으로 하는 인장강도 590MPa급의 가공성 및 재질편차가 우수한 고강도 냉연 TRIP강의 제조방법.
- 중량%로 C: 0.05 ~ 0.20%, Si: 0.8 ~ 2.0%, Mn: 1.2 ~ 2.2%, P: 0.001 ~ 0.1%, S: 0.001 ~ 0.02%, Al: 0.01 ~ 2.0%, N: 0.001 ~ 0.02%, Sb: 0.005 ~ 0.1%, 총 트램프원소(Cu+Cr+Ni+Sn+Pb): 0.18%이하 및 나머지 Fe 및 기타 불가피한 불순물로 조성된 강을 두께 30 ~ 150mm의 박 슬라브로 연속주조하고, 이 박 슬라브를 조압연, 가열, 마무리 압연 및 권취 단계를 통해 열연 스트립을 제조하며, 이 열연 스트립을 산세, 냉간압연, 연속소둔 및 냉각 열처리 단계를 통해 냉연 TRIP강을 제조하는 방법에 있어서,상기 마무리 압연 단계는 마지막 압연 스탠드에서의 압연온도가 [910 - 225C - 65Mn + 15Si + 10P]의 관계식으로 계산된 목표온도의 ±20℃ 범위가 되도록 하며,상기 냉각 열처리 단계는 연속소둔 처리된 스트립을 620 ~ 690℃의 온도로 1 ~ 20℃/s의 냉각속도로 서냉하고, 곧바로 20 ~ 100℃/s의 냉각속도로 급냉한 후 310 ~ 420℃의 온도 범위에서 항온변태 열처리하는 것을 특징으로 하는 인장강도 590MPa급의 가공성 및 재질편차가 우수한 고강도 냉연 TRIP강의 제조방법.
- 중량%로 C: 0.05 ~ 0.20%, Si: 0.8 ~ 2.0%, Mn: 1.2 ~ 2.2%, P: 0.001 ~ 0.1%, S: 0.001 ~ 0.02%, Al: 0.01 ~ 2.0%, N: 0.001 ~ 0.02%, Sb: 0.005 ~ 0.1%, 총 트램프원소(Cu+Cr+Ni+Sn+Pb): 0.18%이하 및 나머지 Fe 및 기타 불가피한 불순물로 조성된 강을 두께 30 ~ 150mm의 박 슬라브로 연속주조하고, 이 박 슬라브를 조압연, 가열, 마무리 압연 및 권취 단계를 통해 열연 스트립을 제조하며, 이 열연 스트립을 산세, 냉간압연, 연속소둔 및 냉각 열처리 단계를 통해 냉연 TRIP강을 제조하는 방법에 있어서,상기 연속소둔 단계는 연속소둔 온도가 [840 - 120C - 45Mn + 25Si + 34P - 45N -25Cu + 8Cr - 30Ni]의 관계식에서 계산된 목표온도의 ±15℃ 범위가 되도록 하고,상기 냉각 열처리 단계는 연속소둔 처리된 스트립을 620 ~ 690℃의 온도로 1 ~ 20℃/s의 냉각속도로 서냉하고, 곧바로 20 ~ 100℃/s의 냉각속도로 급냉한 후 310 ~ 420℃의 온도 범위에서 항온변태 열처리하는 것을 특징으로 하는 인장강도 590MPa급의 가공성 및 재질편차가 우수한 고강도 냉연 TRIP강의 제조방법.
- 중량%로 C: 0.05 ~ 0.20%, Si: 0.8 ~ 2.0%, Mn: 1.2 ~ 2.2%, P: 0.001 ~ 0.1%, S: 0.001 ~ 0.02%, Al: 0.01 ~ 2.0%, N: 0.001 ~ 0.02%, Sb: 0.005 ~ 0.1%, 총 트램프원소(Cu+Cr+Ni+Sn+Pb): 0.18%이하 및 나머지 Fe 및 기타 불가피한 불순물로 조성된 강을 두께 30 ~ 150mm의 박 슬라브로 연속주조하고, 이 박 슬라브를 조압연, 가열, 마무리 압연 및 권취 단계를 통해 열연 스트립을 제조하며, 이 열연 스트립을 산세, 냉간압연, 연속소둔 및 냉각 열처리 단계를 통해 냉연 TRIP강을 제조하는 방법에 있어서,상기 마무리 압연 단계는 하나의 스트립 내에서의 압연 속도차가 15% 이하가 되도록 하고,상기 마무리 압연 단계는 마지막 압연 스탠드에서의 압연온도가 [910 - 225C - 65Mn + 15Si + 10P]의 관계식으로 계산된 목표온도의 ±20℃ 범위가 되도록 하며,상기 연속소둔 단계는 연속소둔 온도가 [840 - 120C - 45Mn + 25Si + 34P - 45N -25Cu + 8Cr - 30Ni]의 관계식에서 계산된 목표온도의 ±15℃ 범위가 되도록 하고,상기 냉각 열처리 단계는 연속소둔 처리된 스트립을 620 ~ 690℃의 온도로 1 ~ 20℃/s의 냉각속도로 서냉하고, 곧바로 20 ~ 100℃/s의 냉각속도로 급냉한 후 310 ~ 420℃의 온도 범위에서 항온변태 열처리하는 것을 특징으로 하는 인장강도 590MPa급의 가공성 및 재질편차가 우수한 고강도 냉연 TRIP강의 제조방법.
- 청구항 1 내지 청구항 4 중 어느 한 청구항에 있어서,상기 연속주조 단계는 주조속도가 4.5 mpm 이상으로 하는 것을 특징으로 하는 인장강도 590MPa급의 가공성 및 재질편차가 우수한 고강도 냉연 TRIP강의 제조방법.
- 청구항 1 내지 청구항 4 중 어느 한 청구항에 있어서,상기 조압연 단계는 조압연기 입측에서의 박 슬라브 표면온도가 950 ~ 1100℃가 되도록 하고, 조압연 시의 누적 압하율이 65 ~ 90%가 되도록 하는 것을 특징으로 하는 인장강도 590MPa급의 가공성 및 재질편차가 우수한 고강도 냉연 TRIP강의 제조방법.
- 청구항 1 내지 청구항 4 중 어느 한 청구항에 있어서,상기 가열 단계는 조압연된 스트립을 920 ~ 1150℃로 가열 또는 보열하는 것을 특징으로 하는 인장강도 590MPa급의 가공성 및 재질편차가 우수한 고강도 냉연 TRIP강의 제조방법.
- 청구항 1 내지 청구항 4 중 어느 한 청구항에 있어서,상기 권취 단계는 마무리 압연된 스트립을 480 ~ 680℃에서 권취하는 것을 특징하는 인장강도 590MPa급의 가공성 및 재질편차가 우수한 고강도 냉연 TRIP강의 제조방법.
- 청구항 1 내지 청구항 4 중 어느 한 청구항에 있어서,상기 냉간압연 단계는 산세된 스트립을 40 ~ 75%의 압하율로 압연하는 것을 특징으로 하는 인장강도 590MPa급의 가공성 및 재질편차가 우수한 고강도 냉연 TRIP강의 제조방법.
- 중량%로 C: 0.06 ~ 0.20%, Si: 0.8 ~ 2.0%, Mn: 1.2 ~ 2.2%, P: 0.001 ~ 0.1%, S: 0.001 ~ 0.02%, Al: 0.01 ~ 2.0%, N: 0.001 ~ 0.02%, 총 트램프원소(Cu+Ni+Sn+Pb): 0.18% 이하 포함되고, Ti: 0.001 ~ 0.1%, Nb: 0.001 ~ 0.1%, V: 0.001 ~ 0.1% 중 하나 이상이 첨가되며, 나머지 Fe 및 기타 불가피한 불순물로 조성된 강을 두께 30 ~ 150mm의 박 슬라브로 연속주조하고, 이 박 슬라브를 조압연, 재가열, 마무리 압연 및 권취 단계를 통해 열연 TRIP강을 제조하는 방법에 있어서,상기 마무리 압연 단계는 하나의 스트립 내에서의 압연 속도차가 15% 이하가 되도록 하고,상기 권취 단계는 상기 마무리 압연된 스트립을 런아웃 테이블에서 25℃/s 이상의 냉각속도로 냉각한 후 350 ~ 470℃의 온도에서 권취하는 것을 특징으로 하는 인장강도 590MPa급의 재질편차가 우수한 고강도 열연 TRIP강의 제조방법.
- 중량%로 C: 0.06 ~ 0.20%, Si: 0.8 ~ 2.0%, Mn: 1.2 ~ 2.2%, P: 0.001 ~ 0.1%, S: 0.001 ~ 0.02%, Al: 0.01 ~ 2.0%, N: 0.001 ~ 0.02%, 총 트램프원소(Cu+Ni+Sn+Pb): 0.18% 이하 포함되고, Ti: 0.001 ~ 0.1%, Nb: 0.001 ~ 0.1%, V: 0.001 ~ 0.1% 중 하나 이상이 첨가되며, 나머지 Fe 및 기타 불가피한 불순물로 조성된 강을 두께 30 ~ 150mm의 박 슬라브로 연속주조하고, 이 박 슬라브를 조압연, 재가열, 마무리 압연 및 권취 단계를 통해 열연 TRIP강을 제조하는 방법에 있어서,상기 마무리 압연 단계는 마지막 압연 스탠드에서의 압연온도가 [910 - 225C - 80Mn + 15Si + 10P]의 관계식으로 계산된 목표온도의 ±20℃ 범위가 되도록 하며,상기 권취 단계는 상기 마무리 압연된 스트립을 런아웃 테이블에서 25℃/s 이상의 냉각속도로 냉각한 후 350 ~ 470℃의 온도에서 권취하는 것을 특징으로 하는 인장강도 590MPa급의 재질편차가 우수한 고강도 열연 TRIP강의 제조방법.
- 중량%로 C: 0.06 ~ 0.20%, Si: 0.8 ~ 2.0%, Mn: 1.2 ~ 2.2%, P: 0.001 ~ 0.1%, S: 0.001 ~ 0.02%, Al: 0.01 ~ 2.0%, N: 0.001 ~ 0.02%, 총 트램프원소(Cu+Ni+Sn+Pb): 0.18% 이하 포함되고, Ti: 0.001 ~ 0.1%, Nb: 0.001 ~ 0.1%, V: 0.001 ~ 0.1% 중 하나 이상이 첨가되며, 나머지 Fe 및 기타 불가피한 불순물로 조성된 강을 두께 30 ~ 150mm의 박 슬라브로 연속주조하고, 이 박 슬라브를 조압연, 재가열, 마무리 압연 및 권취 단계를 통해 열연 TRIP강을 제조하는 방법에 있어서,상기 마무리 압연 단계는 하나의 스트립 내에서의 압연 속도차가 15% 이하가 되도록 하고,상기 마무리 압연 단계는 마지막 압연 스탠드에서의 압연온도가 [910 - 225C - 80Mn + 15Si + 10P]의 관계식으로 계산된 목표온도의 ±20℃ 범위가 되도록 하며,상기 권취 단계는 상기 마무리 압연된 스트립을 런아웃 테이블에서 25℃/s 이상의 냉각속도로 냉각한 후 350 ~ 470℃의 온도에서 권취하는 것을 특징으로 하는 인장강도 590MPa급의 재질편차가 우수한 고강도 열연 TRIP강의 제조방법.
- 청구항 10 내지 청구항 12 중 어느 한 청구항에 있어서,상기 연속주조 단계는 주조속도가 4.5 mpm 이상으로 하는 것을 특징으로 하는 인장강도 590MPa급의 재질편차가 우수한 고강도 열연 TRIP강의 제조방법.
- 청구항 10 내지 청구항 12 중 어느 한 청구항에 있어서,상기 조압연 단계는 조압연기 입측에서의 박 슬라브 표면온도가 950 ~ 1100℃가 되도록 하고, 조압연 시의 누적 압하율이 65 ~ 90%가 되도록 하는 것을 특징으로 하는 인장강도 590MPa급의 재질편차가 우수한 고강도 열연 TRIP강의 제조방법.
- 청구항 10 내지 청구항 12 중 어느 한 청구항에 있어서,상기 재가열 단계는 조압연된 스트립을 920 ~ 1150℃로 가열 또는 보열하는 것을 특징으로 하는 인장강도 590MPa급의 재질편차가 우수한 고강도 열연 TRIP강의 제조방법.
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CN114669598A (zh) * | 2022-04-07 | 2022-06-28 | 山东钢铁集团永锋临港有限公司 | 一种连铸16m方坯直轧棒材的方法 |
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CN107488814B (zh) * | 2017-08-23 | 2018-12-28 | 武汉钢铁有限公司 | 基于CSP流程的800MPa级热轧TRIP钢及制造方法 |
CN107557692B (zh) * | 2017-08-23 | 2019-01-25 | 武汉钢铁有限公司 | 基于CSP流程的1000MPa级热轧TRIP钢及制造方法 |
CN107475627B (zh) * | 2017-08-23 | 2018-12-21 | 武汉钢铁有限公司 | 基于CSP流程的600MPa级热轧TRIP钢及制造方法 |
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CN110229951A (zh) * | 2019-07-29 | 2019-09-13 | 湖南力方轧辊有限公司 | 一种冷轧不锈钢在线退火设备及工艺 |
CN114669598A (zh) * | 2022-04-07 | 2022-06-28 | 山东钢铁集团永锋临港有限公司 | 一种连铸16m方坯直轧棒材的方法 |
CN115094216A (zh) * | 2022-06-23 | 2022-09-23 | 本钢板材股份有限公司 | 一种消除trip高强钢色差缺陷的方法 |
CN115094216B (zh) * | 2022-06-23 | 2023-11-17 | 本钢板材股份有限公司 | 一种消除trip高强钢色差缺陷的方法 |
CN115572893A (zh) * | 2022-09-02 | 2023-01-06 | 武汉钢铁有限公司 | 一种耐大气腐蚀的高强度汽车轮辐用钢及其制造方法 |
CN115739993A (zh) * | 2022-11-18 | 2023-03-07 | 浙江申吉钛业股份有限公司 | 一种宽幅钛合金板的制备方法 |
CN115739993B (zh) * | 2022-11-18 | 2023-05-23 | 浙江申吉钛业股份有限公司 | 一种宽幅钛合金板的制备方法 |
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WO2012064129A3 (ko) | 2012-07-12 |
BR112013011409A2 (pt) | 2016-08-02 |
CN103249847A (zh) | 2013-08-14 |
CN103249847B (zh) | 2015-06-10 |
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