Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
  • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
  • C21D8/0226—Hot rolling
• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • 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
  • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/08—Ferrous alloys, e.g. steel alloys containing nickel
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C38/00—Ferrous alloys, e.g. steel alloys
  • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
  • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
  • C22C38/58—Ferrous alloys, e.g. steel alloys containing chromium with nickel with more than 1.5% by weight of manganese

Definitions

• the present invention relates to a high carbon heat 33 ⁇ 4, particularly a high carbon heat excellent in bending after processing, and the Mit method. Background sickle
• Non-Patent Document 1 As a processing rod for automatic parts using high charcoal ⁇ 3 ⁇ 4, it is possible to increase the thickness and to open a fiber processing chamber that has drastically increased 3 ⁇ 4 ⁇ . Has been put into practical use.
• high-carbon steel is required to be able to be processed without any problems even if it combines multiple processing modes such as pulling, drawing, stretching, bending, and hole expansion. In particular, since bending often occurs after bending after applying traction!], Bending 14 after excellent traction!] Is desired.
• Patent Document 1 After hot rolling a high-carbon coal of a predetermined chemical composition, descaling, heating in a hydrogen atmosphere above 95 volume m ⁇ specified by the chemical composition ⁇ A method for producing a soft, high-coal zone with excellent uniformity and workability by cooling at a cooling rate of 1 ° C or less at a temperature of 100 ° C / hr or less is being tested. Further, Patent Document 2, was cooled 10 ⁇ 100D, until?
• Non-Patent Document 1 Journal of the JSTP, 44, 2003, p.409-413
• Patent Document 1 JP-A-9-157758
• Patent Document 2 JP-A-5-9588
• Patent Document 3 Japanese Patent Laid-Open No. 2003-13145 Disclosure of Invention
• the high carbon hot-spring of ⁇ 3 ⁇ 4 in these submissive techniques is superior in properties when processed in a single processing mode such as tension or 73 ⁇ 4, but bends after tensile processing. Combining multiple processing modes; ⁇ had problems such as cracking.
• An object of the present invention is to provide a high carbon heat exciter having excellent bending properties after tensile processing and an i * "method thereof.
• the inventors have determined the amount of Sol. A1 in the steel, the cooling conditions after hot rolling, the cutting temperature, and the annealing temperature.
• the ability to control properly S has been found to be extremely important ⁇ and the ferrite grain size obtained by the later measurement method should be 5.0 / zm or less, and the ferrite grains with a force aspect ratio of 0 or more It was found that by controlling the area ratio below 1 TO, it was possible to obtain excellent bending characteristics after pulling.
• the present invention has been made on the basis of the above findings, and has a mass of 34, C: 0.2-0.71 Si: 2% or less, 3 ⁇ 4fo: 2% or less, P: 0.03% or less, S: 0.0 , Sol.
• A1 A process of hot rolling steel with a content of 0.01% or less and N: 0.01% or less to a finish of (Ar 3 transformation point-20 ° C) or more to form a hot plate
• the process of cooling the heat plate to 60 ° C / second or more and 120 ° C / second to 650 ° C or less and the heat after the tilt itself and ⁇ Ru step by preparative, heat ⁇ after Ri preparative IiP5, to «a step of ⁇ by a Cl transformation point of ⁇ above 64TfC, the manufacturing i * law high carbon hot ⁇ with.
• heat is glued to 600 ° C or less with a paste of 80 ⁇ / sec or more and less than 120 ° C / sec. It ’s better to pick it up below 550 ° C.
• the present invention also relates to a high-carbon steel sheet that is formed into a cocoon and has a mass of CO. 2
• the area ratio of ferrite grains having a self-spect ratio of 40 or more is more preferable.
• B 0.005 mass y. Cr: 3.5 mass% or less, Ni: 3.5 mass% or less, Mo: 0.7 mass% or less, Cu: 0.1 quality *% or less, Ti: 0.1 mass% or less, b: 0.1 mass% or less, W, V, Zr: 0.1 mass in total.
• FIG. 1 is a diagram showing the relationship between the area ratio of ferrite grains having an aspect ratio of 40 or more and the bending 14 after pulling. Best Mode for Invention
• the amount of C is specified as 0.2 to 0.7%.
• the C content exceeds O. S%, and that the C content is 0.5% 3 ⁇ 4 or less in order to improve the workability.
• Si amount Since Si tends to graphitize carbides and inhibit j1 ⁇ 2A property, the amount is specified to be 23 ⁇ 4 or less, preferably 0.5% or less.
• Mn content When Mn is contained in ii3 ⁇ 4, the ductility tends to be lowered. Therefore, the amount is specified to be 2% or less, preferably 1% or less.
• P content When P is contained in ⁇ , ductility such as stretch flangeability is reduced, and cracks are generated and become fragile. Therefore, the content is specified to be 0.0 «lower, preferably 0.02% 3 ⁇ 4 lower.
• Sol. M amount: SoL Al is the most important element in the present invention. That is, when the amount of Sol. Al exceeds 0.01%, when nitrogen is used as a relatively non-oxidizing atmosphere with relatively high efficiency, A1N is formed on the surface layer when heat is generated in a nitrogen atmosphere. The inventors of the present invention have found that the bending force 14 after working 11 hours is markedly reduced by the surface hardening of the steel sheet and significantly decreases. Therefore, the amount of Sol. A1 is specified to be 0.01% or less.
• N amount When N is contained in »j, the ductility is lowered, so the amount is 0 ⁇ 01% 3 ⁇ 4 lower, preferably 0. lower.
• Fe and unavoidable impurities but for example, B, Cr, Ni, Mo, Cu, Ti, Nb within the range usually added for the purpose of improving i1 ⁇ 2A b properties and softening resistance.
• W
• V or Zr Even if at least one element such as V or Zr is added, the effect of the present invention is not impaired. Specifically, these elements are: ⁇ : 0.005% or less, Cr: 3.5% or less, Ni: 3.5% or less, Mo: 0.7% or less, 01: 0. 1 lower, Ti: 0. 1% lower, Nb: ai lower, W, V, Zr: 0.1 total lower.
• the hot rolling finish should be (Ar 3 transformation point-20 ° C) or higher.
• the Ar 3 transformation point can be calculated from the following equation (1), but actually measured may be used.
• M represents the content of the element M 00.
• correction terms may be introduced. For example, to contain Cr, Mo, Ni force S, -ll X [Cr], +31.5 X [Mo], -15 A correction term such as 2 X [Ni] may be added to the right-hand side of equation (1).
• Cooling conditions after hot rolling In the present invention, the amount of Sol. A1 is low, and although the grain growth is hardly inhibited by the pinning of A1N, ferrite grains are transformed. This is because the strain imparted to the austenite grains during rolling is accumulated by cooling after the hot rolling, and the strain accumulated in the subsequent stage contributes as the core of the ferrite grains. It is estimated to be. If the cooling ⁇ after hot rolling is 60 ° C / second, the strain applied to the austenite grains during rolling is less likely to accumulate. Then, the ferrite grains grow and stick. As a result, the ferrite grain size exceeds 5.0 ⁇ , and the bending habit after the pulling is deteriorated.
• cooling after hot rolling should be 60 ° C / ⁇ or more and 120 ° C / second or less.
• the upper limit of ffil ⁇ is preferably 115 ° C / sec.
• the cooling temperature is 650 ° C or less, preferably 600 ° C or less.
• the cooling rate is 500 ° C. or higher.
• ⁇ Cooling after heat is removed, but if the tempering exceeds 600 ° C, the strain force made austenite at the time of hot rolling is released. Elite particle size exceeds 5.0 ⁇ ⁇ , and bending difficulty after traction DIE deteriorates. Therefore, the tapping shall be 600 ° C or less. In order to obtain a sufficient t & t self-cooling effect, it is preferable to set the temperature at a lower temperature than when the self-cooling is stopped. Note that, since the shape of the heat ⁇ deteriorates, the scraping is preferably 200 ° C or higher, more preferably 350 ° C or higher. When the ratio of ferrite grains with an aspect ratio of 40 or more is reduced to 1TO, the bending characteristics are further improved. To achieve this, ⁇ ⁇ ⁇ «is 80 ° C / sec. It is necessary to keep the temperature below 600 ° C and force winding up to 550 ° C.
• the scale removal means is not particularly limited, but it is preferable to use the usual method. '
• Heat ⁇ ⁇ The heat wrapping board after being removed by scissors or the like is subjected to a force S as spheroidization in order to spheroidize the carbide. At that time, if ⁇ is less than 60 ° C, the ferrite core length becomes insufficient, the area ratio of ferrite grains with an aspect ratio of 40 or more exceeds 15%, and the bending characteristics after drawing are deteriorated. To do. On the other hand, ⁇ 3 ⁇ 4 is austenitization partially proceeds exceeds A Cl transformation point, since pearlite is formed during cooling, bending after pulling ⁇ E ⁇ deteriorates. Therefore, S ⁇ of the hot plate is set to 60 ° C or more and ACl transformation point or less.
• the thickness of the steel sheet is 680 ° C or higher.
• the Ac / transformation point can be calculated from the following equation (2), but actually measured values can also be used.
• Ac! Transformation point 754 83-32. 25 X [C] +23. 32 X [Si]-17. 76 X [Mn] ' ⁇ ⁇ ⁇ (2)
• [M] represents the content (mass) of the element M.
• correction terms may be introduced. For example, ⁇ containing Cr, Mo, and V 17. Add 3 X [Cr], +4 51 X [Mo], +15. 62 X [V] and the corresponding correction term to the right side of Equation (2).
• Heat time is 8 ⁇ 80 hours 3 ⁇ 4g force S preferred.
• the obtained carbide in the soot was measured at about 1/4 position of the chemical, average aspect ratio of about 5.0 or less.
• both the converter and the electric power can be shelfd.
• the high coal mine that has been difficult in this way is made into a slab by rolling ingots for one minute or continuous. Slabs are usually heated and then hot rolled. In the case of a slab made of steel, it may be applied as it is or as it is heat-retained for the purpose of suppressing the temperature drop and rolled for the first time. In addition, when the slab is heated and hot-rolled, the slab temperature should be 1280 ° C or less to avoid deterioration of the surface state due to the scale.
• the hot rolling can be performed by omitting the rolling and only rolling.
• the plate In order to ensure the finish, it is also possible to heat the plate with a heating means such as a sheet bar heater during hot rolling.
• the coil can be kept warm by means such as a slow cooling cover after winding, in order to promote shaping or to reduce hardness. 3 ⁇ 4J?
• the heat wrapping plate is not particularly limited as long as the production of the present invention can be maintained, but a heat of 1.0 to 10. ⁇ is particularly preferable.
• the heat ⁇ fiber can be done either in a box or, ⁇ . After dredging, temper rolling is performed as necessary. Since this temper rolling does not affect the i3 ⁇ 4AtL property, there are no particular restrictions on the conditions.
• the heat ⁇ produced by the method of the upper bowl invention is a heat summary that has been subjected to heat denaturation, and as described above, the average aspect ratio is about 5.0 or less. This is a hot plate with carbides.
• the thermal steel plate of the present application has a ferrite grain size of 5.0 zm or less.
• Ferrite grain size has an effect on bending after rolling, and when the ferrite grain size exceeds 5.0 / zm, many Tsuruta carbides are ejected into the ferrite grains, In Loe, fine voids generated at the interface between the carbide and the parent phase (ferrite) are connected in the bending process and cracks occur.
• the ferrite grain size is set to 5.0 z ra or less, the fine carbides in the ferrite grains are reduced, and the Hengda void generated in the! Since it becomes difficult to be connected in the bending after the bending, it is possible to suppress cracking.
• the area ratio power of ferrite grains with an aspect ratio of 4.0 or more is 5% 3 ⁇ 4 under the heat of ⁇ .
• the ferrite grain shape affects the bending characteristics after the erosion, and if the ferrite grain has an aspect ratio of 4.0 or more, the aspect ratio is 40 or more.
• Such an aspect ratio of 40 or more If the area ratio of ferritic grains exceeds 15%, cracks will occur in the bending process starting from a crack at the pulling S3 ⁇ 4D.
• the area ratio of ferrite grains with such an aspect ratio of 40 or more By making it 15% or less, it is possible to suppress cracking by bending after the pulling opening, more preferably, the area ratio of ferrite grains having an aspect ratio of 40 or more is 10% 3 ⁇ 4 or less. It is.
• o ⁇ 1 to 10 are examples of the present invention
• ⁇ . 11 to 20 are comparative examples.
• the aspect ratio and area ratio of ferrite port and ferrite grain were measured by the following methods. In addition, the following method was applied to the bending after 11 hours of working.
• the ferrite grain size is an average value of the grain size obtained by approximating the ferrite grain to a circle by image interpretation.
• the pect ratio is the average value of (ellipse major axis) / (ellipse minor axis) obtained by ellipsoidal approximation of ferrite grains from the image ⁇ .
• the image of the micro yarn is observed at double magnification, and the image of the ferrite particle size and the ferrite particle size are determined by image folding using the “Image Pro PI us ver.4 0” ( ⁇ ) software of Media Cybernetics.
• the spectrum ratio was determined. Furthermore, an area ratio of 40 or more in aspect ratio is obtained for each ferrite grain, and this is divided by the total area of the field of view to obtain an area ratio for each field of view. -0 or more ferrite grain area ratio.
• Examples No. 1 to 10 which are examples of the present invention, have a ferrite grain size of 5.0 / zm or less, and the area ratio of ferrite grains having a force and a aspect ratio of 40 or more is 15%.
• Tsutsu excellent in bending 14 after working 11e.
• the average aspect ratio of the carbide was 5.0 or less, and the carbide was spheroidized.
• Figure 1 shows the percentage of ferrite grains with an aspect ratio of 40 or more in ferrite with a ferrite of 5 or less.
• the ferrite grain size is set to 5.0 / xm or less and the area ratio of ferrite grains having a force-spect ratio of 4_0 or more is reduced by 15% 3 ⁇ 4 It can be seen that excellent bending characteristics after pulling can be obtained.
• the steel E shown in Table 1 was made into a slab and then heated to 1230 ° C. Hot rolling and heat fibering were performed under the conditions shown in Table 4, and ⁇ o.21-37 in ⁇ .5 was applied. Note that the fiber was made in a nitriding atmosphere (03 ⁇ 4 atmosphere ⁇ ). For the obtained heat ⁇ , the aspect ratio and area ratio of ferrite and ferrite grains were measured by the same method as i, and the bending characteristics after the pulling were examined. In addition, as in Example 1, the effect of carbide masculinization was checked.
• the ratio of ferrite grains having an aspect ratio of 40 or more can be reduced by 1 «.
• the average aspect ratio of the carbides is 5.0 or less, and it is shown that the carbides are shaped.
• E ⁇ I copper whose extinction is within the scope of the present invention is excellent in bending properties after tensile processing, including G and I steels, which include iron and silicon other than the ingredients. Show.

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• 2006
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