WO2017043660A1 - Tôle d'acier et produit émaillé - Google Patents

Tôle d'acier et produit émaillé Download PDF

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Publication number
WO2017043660A1
WO2017043660A1 PCT/JP2016/076847 JP2016076847W WO2017043660A1 WO 2017043660 A1 WO2017043660 A1 WO 2017043660A1 JP 2016076847 W JP2016076847 W JP 2016076847W WO 2017043660 A1 WO2017043660 A1 WO 2017043660A1
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Prior art keywords
enamel
oxide
steel sheet
steel
less
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PCT/JP2016/076847
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English (en)
Japanese (ja)
Inventor
楠見　和久
友清　寿雅
西村　哲
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新日鐵住金株式会社
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Application filed by 新日鐵住金株式会社 filed Critical 新日鐵住金株式会社
Priority to KR1020187006500A priority Critical patent/KR102068499B1/ko
Priority to CN201680051843.1A priority patent/CN107949652B/zh
Priority to AU2016321009A priority patent/AU2016321009C1/en
Priority to JP2016569861A priority patent/JP6115691B1/ja
Priority to MX2018002854A priority patent/MX2018002854A/es
Priority to NZ740281A priority patent/NZ740281A/en
Priority to EP16844521.1A priority patent/EP3348661A4/fr
Publication of WO2017043660A1 publication Critical patent/WO2017043660A1/fr

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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
    • 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
    • C21D8/0236—Cold 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
    • C21D9/48—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals deep-drawing sheets
    • 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
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
    • 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
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/60—Ferrous alloys, e.g. steel alloys containing lead, selenium, tellurium, or antimony, or more than 0.04% by weight of sulfur
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/004—Dispersions; Precipitations
    • 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
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite

Definitions

  • the present invention relates to steel plates and enamel products. This application claims priority based on Japanese Patent Application No. 2015-179722 filed in Japan on September 11, 2015, the contents of which are incorporated herein by reference.
  • Enamel products are made by baking glass onto the surface of enamel steel plates. Enamel products have functions of heat resistance, weather resistance, chemical resistance, and water resistance, so that they have been widely used as materials for kitchen utensils such as pots and sinks, and building materials. Such enamel products are generally manufactured by processing a steel plate into a predetermined shape, assembling the product into a product shape by welding or the like, and then performing enamel treatment (firing treatment).
  • the steel sheet for enamel used as a material for enamel products is required to have firing strain resistance, nail skip resistance, adhesion, bubble resistance, sunspot defect, and the like.
  • good moldability is required.
  • the enamel treatment improves the corrosion resistance in a severe corrosive environment containing sulfuric acid and the like, so that the enamel product is also applicable to the energy field such as power generation equipment.
  • the energy field such as power generation equipment.
  • the reliability of the above-mentioned fatigue, etc. is affected by changes in the structure of the steel sheet in the manufacturing process of enamel products-enamel processing, that is, changes in strength due to differences in the structure of the steel sheet. ing.
  • Patent Document 1 discloses a technique for preventing the deterioration of nail skipping resistance due to the coarsening of the crystal grain size with respect to the change in the structure morphology accompanying the enamel treatment.
  • Patent Document 1 based on a known high-oxygen steel, the composition, size, shape, ratio, and number of inclusions are optimized, and at the same time, a small amount of Ni, Cr, V, and Mo are added. Accordingly, it is described that, by adding Nb, B, and Ti and optimizing the manufacturing conditions of the steel sheet, it is possible to reduce the decrease in resistance to claw even when repeated enamel treatment is performed. ing.
  • Patent Document 2 the structural form of a steel plate for enamel, that is, ferrite, is a problem in which deflection during firing occurs due to strength reduction accompanying crystal grain growth in enamel processing of high-oxygen steel, that is, dimensional accuracy deteriorates. It is described that it is effective to make the particle size uniform by making the particle size uniform.
  • Ni and Cr are added in order to refine the structure of a hot-rolled steel sheet and make grain growth uniform during annealing in the steel sheet manufacturing process.
  • Patent Document 2 it is thought that certain characteristics can be secured in the enamel product subjected to the enamel treatment accompanied by the structural change, but in order to solve the problems related to the crystal grain growth in the enamel process, Addition is essential. That is, to solve the problem, it is necessary to add an expensive alloy element.
  • Patent Document 2 the addition of Cr coarsens the oxide to make it difficult to hinder ferrite grain growth, thereby improving the uniformity of ferrite grain size and suppressing abnormal grain growth, resulting in mixed grains. Is suppressed.
  • this method which does not use the suppression of grain growth by pinning precipitates and inclusions, results in non-uniform grain size when the temperature in the member fluctuates during enamel processing, and the desired effect cannot be obtained.
  • the present invention develops the technology of the steel sheet for enamel described above, and after the enamel treatment, excellent enamel characteristics (claw resistance, adhesion, appearance) and strength characteristics (by enamel treatment). It is an object of the present invention to provide a steel sheet that does not cause a decrease in tensile strength or has a property that can stably suppress a decrease in tensile strength. Moreover, this invention makes it a subject to provide the enamel product provided with the said steel plate and excellent in the enamel characteristic.
  • the present invention was obtained by various studies in order to overcome the problems of conventional steel plates for enamels, and in particular, the chemical composition, Based on knowledge obtained as a result of examining the influence of manufacturing conditions. That is, the present invention is based on the following findings 1) to 4).
  • Claw jump resistance can be improved by controlling precipitates in steel by optimizing steel components and trapping hydrogen in steel which causes claw jump. In particular, it is possible to ensure nail-proof resistance by allowing an oxide of more than 1.0 ⁇ m to 10 ⁇ m to be present in steel and optimizing the diameter and number of the oxides.
  • Nb is a rare metal, and it is environmentally advantageous not to use it. However, when Nb is not contained, the strength reduction after enamel treatment becomes large.
  • the strength after enamel treatment is achieved by optimizing the steel plate component before the enamel treatment, that is, the steel plate component, crystal grain size, and diameter and number of oxides in the steel. It becomes possible to ensure stably (that is, the strength reduction by enamel processing can be suppressed). In particular, it is effective to optimize the number density of the oxide of 0.1 to 1.0 ⁇ m in order to suppress grain growth during the enamel treatment, which is a major factor of strength reduction due to the enamel treatment. 4) By controlling the steelmaking conditions, the oxide size is controlled, and the hot rolling conditions, cold rolling conditions, annealing conditions, and temper rolling conditions are controlled appropriately, so that the form of precipitates in the final product can be controlled. It is possible to control.
  • the present invention has been completed based on the above findings, and the gist of the present invention is as follows.
  • the steel sheet according to one embodiment of the present invention is, in mass%, C: 0.0060% or less, Si: 0.0010 to 0.050%, Mn: 0.05 to 0.50%, P: 0 0.005 to 0.100%, S: 0.0030 to 0.0500%, Al: 0.0010 to 0.010%, Cu: 0.010 to 0.045%, O: 0.0250 to 0.0700 %, N: 0.0010 to 0.0045%, balance: Fe and impurities, the structure contains ferrite, and the average crystal grain size of the ferrite at a position 1/4 of the plate thickness in the plate thickness direction from the surface Is 20.0 ⁇ m or less, contains an oxide containing Fe and Mn, and among the oxides, the number density of the oxides having a diameter larger than 1.0 ⁇ m and not larger than 10 ⁇ m is 1.0 ⁇ 10 3 / mm 2 or more and 5.0 ⁇ 10
  • the steel sheet according to (1) is B, Cr, Ni, As, Ti, Se, Ta, W, Mo, Sn, Sb, La, Ce, Ca, Mg in the impurities in mass%.
  • the total of one or more of: may be limited to 0.100% or less.
  • the steel sheet according to (1) or (2) may be limited to Nb: 0.010% or less in terms of mass% in the impurities.
  • the steel sheet according to any one of (1) to (3) may be a cold-rolled steel sheet.
  • the steel sheet according to any one of (1) to (4) may be an enamel steel sheet.
  • An enamel product according to another aspect of the present invention includes the steel plate according to any one of (1) to (5) above.
  • the steel sheet according to the above aspect of the present invention is excellent in formability, strength after enamel treatment, and claw resistance. It also has excellent aging resistance, enamel adhesion, and appearance after enamel treatment. Therefore, it is suitable as a steel plate for enamel, which is a base material for enamel products applied to kitchen utensils, building materials, energy fields and the like.
  • the enamel product according to the above aspect of the present invention is excellent in enamel characteristics. Therefore, it is suitable for uses such as kitchen utensils, building materials, and energy fields.
  • FIG. 3 is a photograph showing an example of an oxide having a diameter of 0.1 to 1.0 ⁇ m. It is a photograph which shows an example of an oxide with a diameter larger than 1.0 micrometer and 10 micrometers or less.
  • a steel plate according to an embodiment of the present invention (hereinafter referred to as a steel plate according to the present embodiment) will be described in detail.
  • the steel plate according to this embodiment is suitably used as a base material (enamel steel plate) for enamel products.
  • ⁇ C 0.0060% or less>
  • the C content is 0.0060% or less.
  • a lower C content is desirable.
  • the C content is preferably 0.0015% or more.
  • Si is an element having an effect of controlling the composition of the oxide.
  • the Si content is set to 0.0010% or more.
  • excessive Si content may inhibit the enamel characteristics, and at the same time, may cause a large amount of Si oxide to be formed by hot rolling, thereby reducing the resistance to claw jumping. Therefore, the Si content is set to 0.050% or less. From the standpoint of improving foam resistance, sunspot resistance, etc. and obtaining better surface properties after enamel treatment, it is preferably 0.0080% or less.
  • Mn 0.05 to 0.50%>
  • Mn is an important component that affects the composition of oxides that exert an effect on the claw resistance of a steel plate for enamel, and at the same time contributes to increasing the strength of the steel plate.
  • Mn is an element that prevents hot brittleness caused by S during hot rolling.
  • the Mn content is set to 0.05% or more.
  • the Mn content is high, the enamel adhesion is deteriorated and bubbles and black spots are easily generated.
  • the oxide is present in the steel, the deterioration of these characteristics is small.
  • the Mn content is excessive, ductility deteriorates. Therefore, the upper limit of the Mn content is 0.50%.
  • P is an element effective for increasing the strength of a steel sheet. P also has the effect of suppressing strength reduction due to enamel processing. In order to obtain these effects, the P content is set to 0.005% or more. P is an element effective for increasing the recrystallization temperature and suppressing the growth of crystal grains during enamel treatment. When obtaining this effect, the P content is preferably 0.015% or more. On the other hand, if the P content is excessive, P may segregate at a high concentration at the grain boundaries of the steel sheet during enamel processing, which may cause bubbles, black spots, and the like. Therefore, the P content is 0.100% or less. Preferably it is 0.075% or less.
  • S is an element that forms Mn sulfide.
  • the sulfide is compositely precipitated in the oxide, and in the case of the composite precipitation, the resistance to claw jumping can be further improved.
  • S may be contained.
  • the upper limit of the S content is 0.0500%. Preferably it is 0.0300% or less.
  • Al is a strong deoxidizing element. Therefore, careful control is required. If the Al content exceeds 0.010%, it will be difficult to keep the required amount of O in the steel, and it will be difficult to control oxides that are effective in resistance to claw jumping. Therefore, the Al content is set to 0.010% or less. On the other hand, if the Al content is less than 0.0010%, bubble defects are likely to occur in the slab, and the slab is more refined than usual in the steel making stage, so that a great load is imposed on the steel making process. Therefore, the lower limit of the Al content is set to 0.0010%.
  • Cu is an element that controls the reaction between vitreous and steel during enamel treatment and improves the adhesion of the enamel.
  • the Cu content is set to 0.010% or more.
  • the Cu content is set to 0.045% or less. Preferably it is 0.029% or less, More preferably, it is 0.019% or less.
  • O is an element that forms an oxide at the same time as directly affecting the nail resistance and ductility, and affects the nail resistance in relation to the Mn content.
  • the O content is set to 0.0250% or more. Preferably, it is 0.0400% or more.
  • the O content is set to 0.0700% or less.
  • the O content is determined by reacting oxygen in a steel sample of about 0.5 g with a graphite crucible according to JIS G1239, and measuring the generated CO by an infrared absorption method to quantify the concentration. taking measurement.
  • N is an interstitial solid solution element, and when contained in a large amount, ductility deteriorates. Moreover, when there is much N content, anti-aging property will deteriorate. For this reason, the upper limit of N content is made 0.0045%.
  • the lower limit is not particularly limited. However, in the current technology, it is extremely expensive to melt to less than 0.0010%, so the lower limit of the N content is set to 0.0010%.
  • the steel sheet according to the present embodiment basically includes the above elements, with the balance being Fe and impurities.
  • Impurities are components that are mixed from raw materials such as ore or scrap when manufacturing steel materials industrially or due to various factors in the manufacturing process, and do not adversely affect the steel plate according to the present embodiment. It means what is allowed in the range.
  • each element is preferably set in a range that does not affect the value of free oxygen in the casting stage.
  • Nb 0.010% or less
  • Nb is a rare metal, and it is environmentally advantageous not to use it. Therefore, Nb is not added in the steel plate according to this embodiment.
  • Nb may be mixed as an impurity, but is an element that affects the number of inclusions, and the Nb content is preferably limited to 0.010% or less.
  • the steel structure of the steel sheet according to the present embodiment includes an oxide containing Fe and Mn as elements of the deoxidation product.
  • Nb is not added, so Nb is not included in the oxide as an element of the deoxidation product.
  • the oxide preferably does not contain Al, Cr, Si, or the like. This is achieved by adding the above elements so as to limit the content or not to affect the oxide composition.
  • the oxide contained in the steel sheet according to the present embodiment is substantially composed only of Fe, Mn, and O (even if Al, Cr, and Si are inevitably contained, the total content thereof is 15% or less.
  • the oxide does not contain Nb, Al, Cr, Si or the like as an element of the deoxidation product, the oxide can be finely dispersed by adjusting free oxygen during casting.
  • the number and size of oxides should be controlled within a desired range by adjusting free oxygen during the casting process of the present application. Becomes difficult.
  • the number density of the oxide having a diameter greater than 1.0 ⁇ m and not greater than 10 ⁇ m is 1.0 ⁇ 10 3 pieces / mm 2 or more and 5.0 ⁇ 10 4 among the oxides. pieces / mm 2 or less, and a diameter of it is necessary to make the number density of the oxide of 0.1 ⁇ 1.0 ⁇ m 5.0 ⁇ 10 3 cells / mm 2 or more.
  • An oxide having a diameter of more than 1.0 ⁇ m improves nail resistance. If the oxide is smaller than this range, the effect of improving the resistance to claw jumping is reduced. From the viewpoint of the effect of improving the nail skipping resistance, it is not necessary to specifically limit the upper limit of the diameter. However, although depending on the oxygen content, if the number of coarse oxides increases, the number density of the oxides decreases and the effect of inhibiting hydrogen permeation decreases. Moreover, a coarse oxide tends to become a starting point of cracking during processing, and reduces ductility. For this reason, it is preferable that the diameter of the oxide utilized for improving the nail resistance is 10 ⁇ m or less, preferably 5 ⁇ m or less.
  • the oxide having a diameter of more than 1.0 to 10 ⁇ m is controlled in order to improve the nail resistance.
  • the oxide is present in excess of 5.0 ⁇ 10 4 pieces / mm 2 , voids are generated more than necessary at the interface between the oxide and the steel plate base material during processing, and the strength after enamel treatment is reduced. . Therefore, the upper limit of the number density is 5.0 ⁇ 10 4 pieces / mm 2 . Preferably, it is 1.0 ⁇ 10 4 pieces / mm 2 or less.
  • An oxide having a diameter exceeding 1.0 ⁇ m often has a round shape as shown in FIG.
  • an oxide having a diameter of 1.0 ⁇ m or less has an effect of suppressing grain growth in a heat treatment (enamel treatment) step in the production of an enamel product. If the diameter exceeds 1.0 ⁇ m, the effect of suppressing grain growth due to heat input during heat treatment is lost, so the upper limit of the diameter of the oxide utilized for suppressing grain growth is 1.0 ⁇ m or less.
  • the diameter of the oxide in the steel is desirably small, preferably 0.8 ⁇ m or less, and more preferably 0.5 ⁇ m or less.
  • the diameter of the oxide present in the steel is preferably as small as possible, but if it is too small, the analysis of the oxide, that is, the identification of the oxide containing Fe and Mn becomes difficult.
  • the lower limit of the oxide diameter for which the number density is controlled is set to 0.1 ⁇ m or more. That is, in order to suppress grain growth in the heat treatment step, an oxide having a diameter of 0.1 to 1.0 ⁇ m is controlled. An oxide having a diameter of 0.1 to 1.0 ⁇ m often has an angular shape as shown in FIG.
  • the density of the oxide having a diameter of 0.1 ⁇ m to 1.0 ⁇ m and containing Fe and Mn is 1.0 ⁇ 10 5 pieces / mm 2 or less.
  • oxides containing Fe and Mn with a diameter of 0.1 ⁇ m to 1.0 ⁇ m also have the effect of refining the crystal grain size after cold rolling recrystallization. It also contributes to suppression of fracture and fatigue failure.
  • the method for identifying the oxide described above is not particularly limited.
  • the target oxide is one in which Fe, Mn, and O are detected simultaneously
  • a scanning electron microscope (FE-SEM) and an energy dispersive X-ray dispersive analyzer are used for the identification. (EDAX) may be used.
  • the measurement method may be a normal method. However, since it is necessary to determine the concentration of a minute region in particular, it is necessary to pay attention to making the beam diameter of the electron beam sufficiently small (for example, 0.1 to 0.5 ⁇ m). is there.
  • the diameter and number density of the oxide can be measured by the following method.
  • the magnification is 5000 times or more
  • the number of fields of view is 10 or more
  • the size and number of the oxides in the field of view are measured
  • the major axis of the oxide is the oxide diameter.
  • slag and refractory mixed in the manufacturing process may exist as inclusions, but the composition does not include Mn and Fe, and this has no effect of suppressing strength reduction. Such inclusions are not counted.
  • Fe, Mn, and O may be detected at the same time.
  • MnS may be complexly precipitated.
  • the structure of the steel sheet according to this embodiment is mainly composed of ferrite. Therefore, it is effective to reduce the crystal grain size in order to improve the strength.
  • ferrite grain growth occurs due to heat treatment (enamel treatment), the crystal grain size changes, and as a result, the strength (tensile strength) decreases. Further, the fatigue characteristics are also reduced due to the decrease in strength. Reducing the crystal grain size after heat treatment is effective for ensuring the strength of the steel plate after heat treatment. In order to reduce the crystal grain size after the heat treatment, it is important to reduce the grain size before the heat treatment and to suppress the grain growth accompanying the heat treatment.
  • the average crystal grain size of the ferrite in the steel sheet structure before heat treatment needs to be 20.0 ⁇ m or less at a position of 1/4 of the sheet thickness in the sheet thickness direction from the surface (1 / 4t: t is the sheet thickness). It is.
  • the average crystal grain size exceeds 20.0 ⁇ m, it is difficult to increase the strength of the steel sheet. In order to increase the strength, it is desirable that the average crystal grain size is small. However, as the average crystal grain size decreases, the ductility deteriorates. Therefore, it is necessary to determine an optimum crystal grain size for a desired product shape.
  • it is 15.0 ⁇ m or less, more preferably 13.0 ⁇ m or less, and further preferably 11.0 ⁇ m or less.
  • the average crystal grain size of ferrite may be measured according to the cutting method described in JIS G0552.
  • the area ratio of ferrite is 90% or more, more preferably 95% or more, and still more preferably 99% or more.
  • the balance is, for example, an oxide or iron carbide.
  • the crystal grain size of the steel sheet surface layer is particularly small.
  • the crystal grain size of the steel sheet is greatly influenced by the concentration of elements in the steel, particularly P, and the crystal grain size tends to decrease as the P concentration increases.
  • the enamel product according to the present embodiment includes the steel plate according to the present embodiment.
  • it is a product obtained by performing processing, welding, and enamel processing on the steel sheet according to the present embodiment.
  • the preferable manufacturing method of the steel plate which concerns on this embodiment is demonstrated. If the steel plate according to the present embodiment has the above-described configuration, the effect can be obtained, and the manufacturing method does not need to be limited. However, as will be described later, a production method including steps of steelmaking, casting, hot rolling, cold rolling, continuous annealing, and temper rolling is preferable because it can be stably produced. In each step, preferable conditions will be described.
  • the manufacturing point is the control of oxides having the effect of improving the resistance to claw resistance by the oxide containing Fe and Mn and suppressing the abnormal grain growth during the enamel treatment. A relatively large oxide diameter is desirable for improving nail-foil resistance, and a small oxide diameter is desirable for suppressing abnormal grain growth.
  • the oxide of 0.1 to 1.0 ⁇ m is angular as shown in FIG. 1, and it is considered that free oxygen often forms by reaction with steel components after solidification. Therefore, by adjusting the free oxygen in the steelmaking stage and stirring the solidification interface by electromagnetic stirring to adjust the concentration of components such as oxygen at the solidification interface, the crystallization of the oxide of 0.1 to 1.0 ⁇ m is achieved. You can control the number. In addition, it is considered that inclusions exceeding 1.0 to 10 ⁇ m have a round shape as shown in FIG. 2 and are often produced in a liquid state at the molten steel stage.
  • the number of inclusions of more than 1.0 and 10 ⁇ m or less can be controlled by controlling the aggregation and floating of inclusions by controlling the casting speed, the stirring of the molten steel, the degree of superheating of the molten steel, and the like.
  • ⁇ T the degree of superheat of molten steel
  • the casting speed is in the range of 1 to 1.5 m / min.
  • dissolved oxygen can remain at high temperature, and inclusions with a small diameter can be formed at low temperature. That is, by controlling the steelmaking conditions and the casting conditions, it is possible to control the presence state of both the large diameter oxide and the small diameter oxide.
  • the amount of dissolved oxygen (free oxygen) can be measured in a tundish using an oxygen concentration cell. If the secondary refining is stable, it is not necessary to measure each time.
  • the heating temperature is preferably 1150 to 1250 ° C.
  • the heating temperature is higher than 1250 ° C.
  • the amount of primary scale generated is large and the yield is lowered.
  • the rolling rate is preferably 30 to 90% and the finishing temperature is preferably Ar 3 to 950 ° C.
  • the coiling temperature after hot rolling is preferably 550 to 750 ° C.
  • the Ar3 temperature can be obtained by measuring thermal expansion after adding a thermal history and processing simulating hot rolling with a small test piece.
  • the oxide containing Fe and Mn produced in the steel making process and the casting process is stretched by hot rolling.
  • the hot rolling rate cumulative rolling reduction in hot rolling
  • the hot rolling rate exceeds 90%, the oxide in the steel may be stretched too much to obtain good nail resistance.
  • the finishing temperature in the hot rolling is less than Ar3, the rolling is performed at or below the transformation point, and mechanical properties such as ductility as a product deteriorate, and at the same time, the strength change of the steel plate increases, so that the rolling tends to become unstable.
  • the finishing temperature when the finishing temperature is less than Ar3, the microstructure of the hot-rolled steel sheet becomes a mixed grain including coarse grains, and there is a concern that ridging may occur after processing in a cold-rolled annealed sheet using this hot-rolled steel sheet. . Therefore, the finishing temperature needs to be Ar3 or higher, more preferably 900 ° C or higher.
  • the finishing temperature exceeds 950 ° C.
  • the crystal grain size becomes coarse, and it becomes difficult to secure a desired strength.
  • the coiling temperature after hot rolling is preferably 550 ° C. or higher. If it is less than 550 degreeC, the structure form after cold rolling and continuous annealing will become difficult to ensure the ductility and r value which are required for a process. Further, when the coiling temperature exceeds 750 ° C., the crystal grain size becomes large, so that it is difficult to ensure the desired steel plate strength.
  • Cold rolling process The hot-rolled steel sheet is pickled as necessary and then cold-rolled.
  • the cold rolling rate in the cold rolling is important for determining the characteristics of the product, and is preferably 65 to 85%.
  • the oxide containing Fe and Mn formed in the steel making process and the casting process is stretched in accordance with the rolling rate in the hot rolling process. Thereafter, the film is further drawn in a cold rolling process, but cold rolling is processing at about 150 ° C. at the maximum, and the above oxide is hard and thus is not easily drawn. Therefore, it is preferable to perform cold rolling at a cold rolling rate of 65% or more in order to stretch the film appropriately. At this time, voids are generated at both ends in the rolling direction of the oxide.
  • the presence of the voids effectively works against the nail skip resistance but works against the ductility. For this reason, the presence of more voids than necessary causes a decrease in ductility, which in turn impairs the workability and the strength characteristics of the product after enamel treatment. For this reason, the upper limit of the cold rolling rate is set to 85%. When cold rolling is performed at a cold rolling rate higher than this, the voids formed at the initial stage of rolling can be seen to be crushed and disappear due to an increase in the cold rolling rate. However, since they are not systematically connected, it is assumed that the introduction of strain due to processing becomes a starting point of fracture and deteriorates ductility.
  • Continuous annealing is performed on the cold-rolled steel sheet.
  • the annealing temperature in the continuous annealing process is desirably 700 to 850 ° C.
  • the annealing temperature may be less than 700 ° C.
  • the annealing temperature exceeds 850 ° C., it is preferable for mechanical properties because ductility and the like are improved.
  • voids generated in the cold rolling process tend to disappear due to diffusion, and the nail skip resistance deteriorates. To do. For this reason, it is preferable that the annealing temperature of a continuous annealing process sets an upper limit to 850 degreeC.
  • temper rolling may be performed mainly for shape control.
  • the amount of strain introduced into the steel sheet changes depending on the temper rolling rate simultaneously with shape control.
  • the temper rolling ratio is increased, that is, when the amount of strain introduced into the steel sheet is increased, abnormal grain growth during enamel processing is promoted.
  • the temper rolling rate of temper rolling is preferably 1.5% or less.
  • the enamel product according to the present embodiment is obtained by processing the steel plate according to the present embodiment into a predetermined shape, then assembling the product into a product shape by welding or the like, and performing enamel processing.
  • the enamel treatment may be performed under known conditions. For example, by heating a steel plate coated with glaze to 800 to 850 ° C. and holding it for 1 to 10 minutes, the vitreous vitreous and the steel plate can be brought into close contact with each other. That's fine.
  • the rolling rate of cold rolling was changed in the range of Table 3 and Table 4, and it was set as the cold-rolled steel plate, and also after performing continuous annealing at 780 degreeC, temper rolling was given, and plate thickness 0.
  • the steel plate was 8 mm.
  • the sheet thickness of the hot-rolled steel sheet was changed with respect to the rolling rate of cold rolling.
  • the 5-point Vickers hardness was measured at a load of 0.98 N at a position of 1/4 of the plate thickness, and the average value was taken as the hardness at the measurement position. Moreover, said measurement was performed in the 10 or more position which opened the space
  • the tensile strength after enamel treatment is 0.85 (85%) or more of the tensile strength before enamel treatment
  • the minimum value of hardness after enamel treatment is 0.85 or more of the minimum value of hardness before enamel treatment.
  • ⁇ Aging resistance> Aging resistance was evaluated by an aging index.
  • the aging index is a yield stress difference between before and after JIS No. 5 tensile test piece is applied with 10% pre-strain and subjected to aging at 100 ° C. for 60 minutes. When the yield stress difference was 30 MPa or less, it was judged that the aging resistance was excellent (OK).
  • the enamel characteristics were examined as follows. ⁇ Nail jump resistance> The nail jump resistance was evaluated by a dry type powder electrostatic coating method in which a glaze of 100 ⁇ m was applied and baked in the atmosphere at a furnace temperature of 830 ° C. for 5 minutes. The steel plate after the enamel treatment is put into a constant temperature bath at 160 ° C. for 10 hours, and a nail skipping acceleration test is performed. A: Excellent, B: Slightly excellent, C: Normal, D: There is a problem The case of D was determined to be rejected.
  • ⁇ Enamel adhesion> For enamel adhesion, the steel plate treated with the enamel was dropped from a 1-meter height with a 2 kg ball head weight, and the enamel peeling state of the deformed part was measured with 169 palpation needles. It was evaluated with. If the area ratio of the unpeeled portion was 40% or more, there was no problem, and if it was less than 40%, it was judged that the adhesion was poor.
  • ⁇ Appearance> The appearance after enamel treatment is the same as above, and visually observe the enameled steel sheet, and observe the condition of bubbles and sunspots.
  • the conventional enamel steel plate is superior in nail skipping resistance without deteriorating aging resistance, enamel adhesion, and appearance, and tensile by enamel treatment. It was confirmed that it is possible to provide an enameled steel sheet that can stably suppress a decrease in strength.
  • the steel sheet according to the above aspect of the present invention is excellent in formability, nail skipping resistance and strength characteristics after enamel treatment when applied to kitchen utensils, building materials, energy fields and the like after enamel treatment. Therefore, it is suitable as a steel plate for enamel and has high industrial applicability.

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

Abstract

L'invention concerne une tôle d'acier contenant, en termes de % en masse, jusqu'à 0,0060 % de C, 0,0010 à 0,050 % de Si, 0,05 à 0,50 % de Mn, 0,005 à 0,100 % de P, jusqu'à 0,0500 % de S, 0,0010 à 0,010 % d'Al, 0,010 à 0,045 % de Cu, 0,0250 à 0,0700 % d'O et 0,0010 à 0,0045 % de N, le reste comprenant du Fe et des impuretés inévitables. La tôle d'acier a une structure qui comprend de la ferrite et la ferrite située à une profondeur dans le sens de l'épaisseur de la tôle correspondant à 1/4 de l'épaisseur de la tôle à partir d'une surface de la tôle d'acier a un diamètre moyen des grains cristallins inférieur ou égal à 20,0 µm. La structure contient des oxydes contenant du Fe et du Mn. Parmi les oxydes, la densité en nombre des oxydes ayant des diamètres supérieurs à 1,0 µm mais inférieurs ou égaux à 10 µm est de 1,0 × 103 à 5,0 × 104 grains/mm2 et la densité en nombre des oxydes ayant des diamètres de 0,1 à 1,0 µm est supérieure ou égale à 5,0 × 103 grains/mm2.
PCT/JP2016/076847 2015-09-11 2016-09-12 Tôle d'acier et produit émaillé WO2017043660A1 (fr)

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KR1020187006500A KR102068499B1 (ko) 2015-09-11 2016-09-12 강판 및 법랑 제품
CN201680051843.1A CN107949652B (zh) 2015-09-11 2016-09-12 钢板及搪瓷制品
AU2016321009A AU2016321009C1 (en) 2015-09-11 2016-09-12 Steel sheet and enameled product
JP2016569861A JP6115691B1 (ja) 2015-09-11 2016-09-12 鋼板およびほうろう製品
MX2018002854A MX2018002854A (es) 2015-09-11 2016-09-12 Lamina de acero y producto esmaltado.
NZ740281A NZ740281A (en) 2015-09-11 2016-09-12 Steel sheet and enameled product
EP16844521.1A EP3348661A4 (fr) 2015-09-11 2016-09-12 Tôle d'acier et produit émaillé

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JPWO2021193953A1 (fr) * 2020-03-27 2021-09-30
US11236427B2 (en) 2017-12-06 2022-02-01 Polyvision Corporation Systems and methods for in-line thermal flattening and enameling of steel sheets
CN114214557A (zh) * 2021-11-16 2022-03-22 马鞍山钢铁股份有限公司 一种双面搪瓷用钢及其制造方法和应用

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WO2020218572A1 (fr) * 2019-04-24 2020-10-29 日本製鉄株式会社 Tôle d'acier
CN111485173B (zh) * 2020-04-09 2020-12-08 广东德纳斯金属制品有限公司 一种新型恒温材料及其制备方法和应用
KR102484992B1 (ko) * 2020-11-18 2023-01-05 주식회사 포스코 강도, 성형성 및 표면 품질이 우수한 도금강판 및 이의 제조방법
KR102501947B1 (ko) * 2020-12-21 2023-02-20 주식회사 포스코 법랑용 강판 및 그 제조방법

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US11236427B2 (en) 2017-12-06 2022-02-01 Polyvision Corporation Systems and methods for in-line thermal flattening and enameling of steel sheets
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CN114214557A (zh) * 2021-11-16 2022-03-22 马鞍山钢铁股份有限公司 一种双面搪瓷用钢及其制造方法和应用

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AU2016321009A1 (en) 2018-03-15
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MX2018002854A (es) 2018-06-15
EP3348661A4 (fr) 2019-02-13
CN107949652B (zh) 2020-04-07
JP6115691B1 (ja) 2017-04-19
JPWO2017043660A1 (ja) 2017-09-07
NZ740281A (en) 2019-01-25
AU2016321009B2 (en) 2019-08-22
KR102068499B1 (ko) 2020-01-22
AU2016321009C1 (en) 2019-11-21

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