EP3348661A1 - Tôle d'acier et produit émaillé - Google Patents

Tôle d'acier et produit émaillé Download PDF

Info

Publication number
EP3348661A1
EP3348661A1 EP16844521.1A EP16844521A EP3348661A1 EP 3348661 A1 EP3348661 A1 EP 3348661A1 EP 16844521 A EP16844521 A EP 16844521A EP 3348661 A1 EP3348661 A1 EP 3348661A1
Authority
EP
European Patent Office
Prior art keywords
steel sheet
oxides
less
enameling
diameter
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP16844521.1A
Other languages
German (de)
English (en)
Other versions
EP3348661A4 (fr
Inventor
Kazuhisa Kusumi
Toshimasa Tomokiyo
Satoshi Nishimura
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nippon Steel Corp
Original Assignee
Nippon Steel and Sumitomo Metal Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nippon Steel and Sumitomo Metal Corp filed Critical Nippon Steel and Sumitomo Metal Corp
Publication of EP3348661A1 publication Critical patent/EP3348661A1/fr
Publication of EP3348661A4 publication Critical patent/EP3348661A4/fr
Withdrawn legal-status Critical Current

Links

Images

Classifications

    • 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 a steel sheet and an enameled product.
  • An enameled product is obtained by firing a glass material on the surface of a steel sheet for vitreous enameling.
  • Enameled products have functions of heat resisting properties, weather resistance, chemical resistance, and water resistance and thus are widely used as materials for kitchen utensils such as pots and sinks, building materials, and the like in the related art.
  • such an enameled product is manufactured by processing a steel sheet into a predetermined shape, then assembling the steel sheet into a product shape by welding or the like, and thereafter performing an enameling treatment (firing treatment) thereon.
  • Patent Document 1 a technique for preventing deterioration of fishscale resistance caused by grain diameter coarsening is described, for example, in Patent Document 1.
  • Patent Document 1 it is described that it is possible to reduce the deterioration of fishscale resistance even in a case where an enameling treatment is repeatedly performed by optimizing the composition, size, shape, proportion, and number of inclusions in known high oxygen steel as the base, by adding a small amount of Ni, Cr, V, and Mo, and further adding Nb, B, and Ti as necessary, and by optimizing manufacturing conditions of a steel sheet.
  • Patent Document 2 it is described that regarding a problem of deterioration of dimensional accuracy caused by bending during firing due to the decrease in strength with grain growth during enameling treatment for a high oxygen steel, it is effective to decrease the grain diameter distribution by uniformizing the microstructural morphology, that is, ferrite grain diameter, of a steel sheet for vitreous enameling.
  • the addition of Ni and Cr is performed for refinement of the structure of a hot rolled steel sheet in a steel sheet manufacturing process and uniformization of grain growth during annealing.
  • Patent Documents 1 and 2 it is considered that certain properties of the enameled products subjected to the enameling treatment with microstructural change can be secured.
  • the addition of Ni is essential. That is, there is a need to add an expensive alloying element to solve the problem.
  • Patent Document 2 the uniformity of the ferrite grain diameter is improved, abnormal grain growth is suppressed, and the formation of duplex grains is suppressed by making it difficult to inhibit ferrite grain growth by oxide coarsening through the addition of Cr.
  • a high strength steel sheet that sufficiently satisfies the strength properties as an index of fishscale resistance and steel sheet reliability, which are important properties of a steel sheet for vitreous enameling, while considering the manufacturing process, is not provided in a current situation, and objects to further improve the properties still remain.
  • the present invention develops the above-described technique of the steel sheet for vitreous enameling, and an object thereof is to provide a steel sheet capable of obtaining aging resistance, formability, excellent enameling properties (fishscale resistance, adhesion, and external appearance) after an enameling treatment, and strength properties (properties in which the decrease in tensile strength due to an enameling treatment does not occur, or the decrease in tensile strength can be stably suppressed).
  • another object of the present invention is to provide an enameled product which has excellent enameling properties by including the steel sheet.
  • the present invention has been obtained by performing various examinations in order to overcome the problems of the steel sheet for vitreous enameling in the related art, and is based on findings obtained as a result of examination of the influence of chemical compositions and manufacturing conditions on the fishscale resistance, suppression of the decrease in the strength, and the like of a steel sheet after an enameling treatment.
  • the present invention is based on the following findings of 1) to 4).
  • the present invention has been completed on the basis of the above findings, and the gist of the present invention is as follows.
  • the steel sheet according to the aspect of the present invention is excellent in formability and strength and fishscale resistance after an enameling treatment.
  • the steel sheet is also excellent in aging resistance, enamel adhesion, and external appearance after the enameling treatment. Therefore, the steel sheet is suitable as a steel sheet for vitreous enameling, which is the substrate of an enameled product applied to kitchen utensils, building materials, and the field of energy.
  • the enameled product according to the aspect of the present invention has excellent enameling properties. Therefore, the enameled product is suitable for applications such as kitchen utensils, building materials, and the field of energy.
  • a steel sheet according to an embodiment of the present invention (hereinafter, a steel sheet according to this embodiment) will be described in detail.
  • the steel sheet according to this embodiment is suitably used as the substrate of an enameled product (steel sheet for vitreous enameling).
  • the C content is set to 0.0060% or less.
  • the C content is preferably low.
  • the C content is preferably 0.0015% or more.
  • Si is an element having an effect of controlling the composition of oxides.
  • the Si content is set to 0.0010% or more.
  • the excess Si content inhibits the enameling properties and simultaneously forms a large amount of Si oxide during hot rolling, and there may be cases where the fishscale resistance decreases. Therefore, the Si content is set to 0.050% or less. From the viewpoint of improving bubble resistance and black spot resistance and obtaining better surface properties after the enameling treatment, it is preferable that the Si content is set to 0.0080% or less.
  • Mn relates to the O content and is an important component that affects the composition of oxides having an effect on the fishscale resistance of a steel sheet for vitreous enameling and contributes to the high-strengthening of the steel sheet. Furthermore, Mn is an element that prevents hot embrittlement caused by S during a hot rolling. In order to obtain these effects, the Mn content is set to 0.05% or more. Typically, as the Mn content increases, the enamel adhesion is deteriorated and bubbles and black spots are likely to be generated. However, in a case of the presence of Mn as oxides in steel, the degree of deterioration of these properties is small. However, when the Mn content is excessive, the ductility deteriorates. Therefore, the upper limit of the Mn content is set to 0.50%.
  • P is an element effective in the high-strengthening of the steel sheet.
  • P also has an effect of suppressing the decrease in strength due to the enameling treatment.
  • the P content is set to 0.005% or more.
  • P is an element effective also in suppressing the growth of grains during the enameling treatment by raising the recrystallization temperature. In order to obtain this effect, it is preferable that the P content is set to 0.015% or more.
  • the P content is set to 0.100% or less.
  • the P content is preferably 0.075% or less.
  • S is an element that forms Mn sulfides.
  • the sulfides may be precipitated with oxides as composite precipitates, and in a case that sulfide is precipitated as composite precipitate, the fishscale resistance can be further improved.
  • S may be contained.
  • it is desirable that the S content is set to 0.0030% or more.
  • the S content is more preferably 0.0100% or more, and even more preferably 0.0150% or more.
  • the upper limit of the S content is set to 0.0500%, and preferably 0.0300% or less.
  • Al is a strong deoxidizing element. Therefore, it is necessary to carefully control Al content.
  • the Al content exceeds 0.010%, it is difficult to contain a necessary amount of O in steel and it is difficult to control the oxides effective in fishscale resistance. Therefore, the Al content is set to 0.010% or less.
  • the Al content is less than 0.0010%, bubble defects are likely to occur in a slab, and a higher degree of refinement than in the related art is necessary for the slab in the steelmaking stage, and a heavy burden is imposed on the steelmaking process. Therefore, the lower limit of the Al content is set to 0.0010%.
  • the Cu is an element that improves the enamel adhesion by controlling the reaction between a glass material and steel during the enameling treatment. In order to obtain the effect, the Cu content is set to 0.010% or more. On the other hand, when the Cu content is excessive, not only is the reaction between the glass material and the steel inhibited, but also there may be cases where the ductility is deteriorated. In order to avoid such adverse effects, the Cu content is set to 0.045% or less. The Cu content is preferably 0.029% or less, and more preferably 0.019% or less.
  • the O content is an element that directly affects fishscale resistance and ductility and forms oxides, and affects fishscale resistance in relation to the Mn content.
  • the O content is set to 0.0250% or more.
  • the O content is preferably 0.0400% or more.
  • the O content is set to 0.0700% or less.
  • the O content is measured by reacting oxygen in about 0.5 g of a steel sample with a graphite crucible in accordance with JIS G 1239, measuring generated CO by an infrared absorption method, and quantifying the concentration.
  • N is an interstitial solid solution element, and ductility is deteriorated when a large amount of N is contained. In addition, when the N content is large, the aging resistance is deteriorated. Therefore, the upper limit of the N content is set to 0.0045%. Although there is no need to limit the lower limit, significant costs are incurred by melting to a proportion of less than 0.0010% of N in current techniques, and thus the lower limit of the N content is set to 0.0010%.
  • the steel sheet according to this embodiment basically contains the above-described elements, and the remainder of Fe and impurities.
  • the impurities are components incorporated from raw materials such as ore and scrap when steel is industrially manufactured, or by various factors in the manufacturing process and mean components that are allowed in a range in which the steel sheet according to this embodiment is not adversely affected.
  • Cr, Ni, B, As, Ti, Se, Ta, W, Mo, Sn, Sb, La, Ce, Ca, and Mg are impurities which are elements that do not need to be positively contained but are unavoidably incorporated. In general, these elements are rarely incorporated independently, and two or more elements are incorporated, for example, like Cr and Ni.
  • the total amount of these elements is preferably limited to 0.100% or less, more preferably 0.050% or less, and even more preferably 0.010% or less.
  • each element in a case where these elements act as deoxidizing elements, the elements affect the value of free oxygen, and there may be cases where it is difficult to adjust the free oxygen. Therefore, it is preferable that the upper limit of each element is set to be in a range in which the value of free oxygen is not affected in a casting stage.
  • Nb is a rare metal, and it is environmentally advantageous not to use Nb. Therefore, Nb is not added to the steel sheet according to this embodiment. Nb may be incorporated as an impurity. However, Nb 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 this embodiment includes oxides containing Fe and Mn as elements of the deoxidation product. Since Nb is not added to the steel sheet according to this embodiment, Nb is not included as an element of the deoxidation product in the oxides. In addition, it is preferable that the oxides do not contain Al, Cr, Si, and the like. This is accomplished by limiting the amounts of the above-mentioned elements or adding the elements so as not to affect the composition of the oxides. However, even when Al, Cr, Si, and the like are not added as deoxidizing agents at the time of adjusting the molten steel components, there may be cases where Al, Cr, Si, and the like are detected from the oxides in a proportion of about 6% or less when the oxides are detected.
  • the components contained in the oxides in a proportion of about 15% or less, and preferably about 6% or less are not counted as elements of the deoxidation product.
  • the oxides contained in the steel sheet according to this embodiment are substantially composed only of Fe, Mn, and O (even if Al, Cr, and Si are unavoidably contained, the total amount thereof is 15% or less).
  • the oxides may be precipitated as composite oxides with sulfides such as MnS.
  • the oxides do not contain Nb, Al, Cr, Si, and the like as elements of the deoxidation product, the oxides can be finely dispersed by adjusting free oxygen during casting.
  • the number density of the oxides having a diameter of more than 1.0 ⁇ m and 10 ⁇ m or less is 1.0 ⁇ 10 3 grains/mm 2 or more and 5.0 ⁇ 10 4 grains/mm 2 or less, and the number density of the oxides having a diameter of 0.1 to 1.0 ⁇ m is 5.0 ⁇ 10 3 grains/mm 2 or more.
  • the oxides having a diameter of more than 1.0 ⁇ m contributes to improve fishscale resistance.
  • the effect of improving fishscale resistance is reduced.
  • the diameter of the oxides utilized for improving the fishscale resistance is 10 ⁇ m or less, and preferably 5 ⁇ m or less. That is, in order to improve the fishscale resistance, oxides having a diameter of more than 1.0 to 10 ⁇ m are controlled.
  • the upper limit of the number density is set to 5.0 ⁇ 10 4 grains/mm 2 , and preferably 1.0 ⁇ 10 4 grains/mm 2 or less.
  • the oxides having a diameter of more than 1.0 ⁇ m have a round shape as shown in FIG. 2 in many cases.
  • the oxides having a diameter of 1.0 ⁇ m or less have an effect of suppressing grain growth in a heat treatment (enameling treatment) process during the manufacturing of the enameled product.
  • a heat treatment enameling treatment
  • the diameter of the oxides in steel is preferably small, preferably 0.8 ⁇ m or less, and even more preferably 0.5 ⁇ m or less. It is desirable that the diameter of the oxides present in steel is as small as possible.
  • the lower limit of the diameter of the oxides as an object of controlling the number density is set to 0.1 ⁇ m or more. That is, in order to suppress grain growth in the heat treatment process, the oxides having a diameter of 0.1 to 1.0 ⁇ m are controlled.
  • the oxides having a diameter of 0.1 to 1.0 ⁇ m have an angular shape as shown in FIG. 1 in many cases.
  • the density of the oxides containing Fe and Mn with a diameter of 0.1 ⁇ m or more and 1.0 ⁇ m or less is set to 1.0 ⁇ 10 5 grains/mm 2 or less.
  • the oxides containing Fe and Mn with a diameter of 0.1 ⁇ m to 1.0 ⁇ m also have an effect of refining the grain diameter after cold rolling and recrystallization, and thus contribute to bending workability and suppression of breaking and fatigue fracture when a member formed by processing steel is used.
  • a method of identifying the above-described oxides is not particularly limited.
  • oxides from which Fe, Mn, and O are simultaneously detected are objects, for the identification thereof, for example, field-emission scanning electron microscopy (FE-SEM) and an energy dispersive X-ray dispersive analyzer (EDAX) may be used.
  • the measurement method may be an ordinary method.
  • the beam diameter of an electron beam is set to be sufficiently small (for example, 0.1 to 0.5 ⁇ m).
  • the diameter and the number density of the oxides can be measured by the following method. That is, with the FE-SEM, the magnification is set to 5,000-fold or more, the number of visual fields is set to 10 or more, the size and number of the corresponding oxides in the visual fields are measured, and the major axis of the oxide is determined as the diameter of the oxide.
  • the number density is obtained by calculating the number of oxides having a major axis of 0.1 ⁇ m to 1.0 ⁇ m and the number of oxides having a major axis of more than 1.0 ⁇ m to 10.0 ⁇ m among the oxides in the visual fields, multiplying the number by a value obtained by dividing the unit area (mm 2 ) by the total area of the visual fields, and thus converting the number into the number per unit area.
  • the composition of the inclusions does not include Mn and Fe and the inclusions do not have an effect of suppressing the decrease in strength, such inclusions are not counted.
  • Fe, Mn, and O may be simultaneously detected from the oxides as the measurement objects in this embodiment, and for example, MnS and the like may be precipitated as composite oxides.
  • microstructure (metallographic structure) of the steel sheet according to this embodiment will be described.
  • the microstructure of the steel sheet according to this embodiment primarily contains ferrite. Therefore, in order to improve the strength, it is effective to reduce the grain diameter.
  • the grain diameter changes due to ferrite grain growth in the heat treatment (enameling treatment), and as a result, the strength (tensile strength) decreases. In addition, due to the decrease in strength, the fatigue properties are also deteriorated. Decreasing the grain diameter after the heat treatment is effective for securing the strength of the steel sheet after the heat treatment. In order to decrease the grain diameter after the heat treatment, it is important to decrease the grain diameter before the heat treatment and suppress grain growth due to the heat treatment.
  • the average grain diameter of ferrite in the steel sheet microstructure before the heat treatment needs to be 20.0 ⁇ m or less at a thickness 1/4 position (1/4t: t is sheet thickness) in a through-thickness direction from the surface of the steel sheet.
  • t is sheet thickness
  • the optimal grain diameter is preferably 15.0 ⁇ m or less, more preferably 13.0 ⁇ m or less, and even more preferably 11.0 ⁇ m or less.
  • the average grain diameter of the ferrite may be measured according to the intercept method described in JIS G 0552 or the like.
  • the area ratio of the ferrite is 90% or more, more preferably 95% or more, and even more preferably 99% or more.
  • the remainder is, for example, oxide or iron carbide.
  • the grain diameter of the surface layer of the steel sheet is small.
  • the grain diameter of the steel sheet is greatly influenced by the concentration of elements in steel, particularly P, and as the concentration of P increases, the grain diameter tends to decrease.
  • the enameled product according to this embodiment includes the steel sheet according to this embodiment.
  • the enameled product is a product obtained by performing processing, welding, and an enameling treatment on the steel sheet according to this embodiment.
  • the steel sheet according to this embodiment is obtained as long as the steel sheet has the above-described configuration, and thus there is no need to limit the manufacturing method.
  • the steel sheet can be stably manufactured according to a manufacturing method including each of steelmaking, casting, hot rolling, cold rolling, continuous annealing, and temper rolling processes, which is preferable.
  • the points in the manufacturing are the improvement of fishscale resistance by the oxides containing Fe and Mn and the control of the oxides having the effect of suppressing abnormal grain growth during the enameling treatment. It is preferable that the diameter of the oxides is relatively large in order to improve the fishscale resistance, and it is preferable that the diameter of the oxides is small in order to suppress abnormal grain growth.
  • the concentration of oxygen in steel is high, oxide having a large diameter is generated. On the other hand, the concentration of oxygen is low, the diameter of oxide is refined.
  • the oxides of 0.1 to 1.0 ⁇ m are angular as shown in FIG. 1 , it is considered that the oxides of 0.1 to 1.0 ⁇ m are generated by the reaction between free oxygen and the steel components after solidification. Therefore, by stirring the solidification interface through electromagnetic stirring to adjust free oxygen in the steelmaking stage and adjust the concentration of components such as oxygen at the solidification interface, the number of crystallized grains of the oxides of 0.1 to 1.0 ⁇ m can be controlled.
  • inclusions of more than 1.0 to 10 ⁇ m have round shapes as shown in FIG. 2 , it is considered that the inclusions of more than 1.0 to 10 ⁇ m are formed in a liquid state in a molten steel stage in many cases. Therefore, aggregation and floating of the inclusions are controlled by controlling the casting rate, stirring of the molten steel, the degree of overheating of the molten steel, and the like, thereby controlling the number of inclusions of more than 1.0 and 10 ⁇ m or less.
  • ⁇ T the degree of overheating of the molten steel
  • the casting rate is set to be in a range of 1 to 1.5 m/min.
  • free oxygen in the mold is controlled to about 250 to 700 ppm by adding a minute amount of a deoxidizing element to a degree that the deoxidizing element does not affect degassing or the oxide composition during secondary refining and then the resultant is cast by cooling at 1.0 to 5.0 °C/s in a range between 1200°C to 1500°C.
  • the amount of dissolved oxygen (free oxygen) can be measured in a tundish using an oxygen concentration cell. In a case where production during the secondary refining is stable, it is not necessary to measure the amount of dissolved oxygen each time.
  • the heating temperature is preferably 1150°C to 1250°C.
  • the heating temperature exceeds 1250°C, the amount of primary scale generated is large, resulting in the decrease in yield.
  • the heating temperature is lower than 1150°C, due to the decrease in the temperature during rolling, the rolling load increases.
  • the rolling reduction ratio is 30% to 90%
  • the finishing temperature is Ar3 to 950°C.
  • the coiling temperature is preferably 550°C to 750°C.
  • the Ar3 temperature can be obtained by thermal expansion measurement result after applying a thermal history that simulates hot rolling to a small test piece and processing the resultant.
  • the oxides containing Fe and Mn produced in the steelmaking process and the casting process are stretched by hot rolling.
  • the hot rolling reduction ratio cumulative rolling reduction ratio during hot rolling
  • 30% or more it is possible to sufficiently stretch the oxides containing Fe and Mn in steel.
  • the hot rolling reduction ratio exceeds 90%, there may be cases where the oxides in steel are excessively stretched and good fishscale resistance is not obtained.
  • the finishing temperature in the hot rolling is lower than Ar3
  • the rolling is performed at a temperature equal to or lower than the transformation point, and mechanical properties such as ductility as a product deteriorate. Simultaneously, the strength of the steel sheet is significantly changed, and thus the rolling tends to be unstable.
  • the finishing temperature needs to be set to Ar3 or higher, and is more desirably 900°C or higher.
  • the finishing temperature exceeds 950°C, the grain diameter becomes coarse, and it is difficult to secure desired strength.
  • the coiling temperature after the hot rolling is preferably set to 550°C or higher.
  • the coiling temperature is lower than 550°C, it is difficult for the microstructural after cold rolling and continuous annealing to secure necessary ductility for processing and r value.
  • the coiling temperature exceeds 750°C, the grain diameter increases, and it is difficult to secure the desired steel sheet strength.
  • the cold rolling reduction ratio during the cold rolling is important for determining the properties of the product and is preferably 65% to 85%.
  • the oxides containing Fe and Mn formed in the steelmaking process and the casting process are stretched according to the rolling reduction ratio in the hot rolling process. Thereafter, the oxides are further stretched in the cold rolling process.
  • the cold rolling is a process performed at about 150°C at the maximum and the oxides are hard, the oxides are less likely to be stretched. Therefore, for appropriate stretching, it is preferable that the cold rolling is performed at a cold rolling reduction ratio of 65% or more.
  • the upper limit of the cold rolling reduction ratio is set to 85%. In a case of performing cold rolling at a higher cold rolling reduction ratio, it seems that the voids formed at the initial stage of the rolling is crushed and disappeared due to the increase in the cold rolling reduction ratio, in the observed microstructure. However, it is assumed that since the voids are not structurally bonded together, the voids act as the fracture origin due to the introduction of strain during processing and deteriorate the ductility.
  • the annealing temperature in the continuous annealing process is preferably set to 700°C to 850°C.
  • the annealing temperature may be lower than 700°C.
  • the annealing temperature exceeds 850°C, regarding the mechanical properties, ductility and the like are improved, which is preferable.
  • the voids generated in the cold rolling process tend to disappear by diffusion, and thus the fishscale resistance is deteriorated. Therefore, it is preferable that the upper limit of the annealing temperature in the continuous annealing process is set to 850°C.
  • temper rolling may be performed mainly for the purpose of shape control.
  • the amount of strain introduced into the steel sheet varies depending on the temper rolling reduction ratio as well as the shape control.
  • the temper rolling reduction ratio increases, that is, when the amount of strain introduced into the steel sheet increases, abnormal grain growth during the enameling treatment is promoted. Therefore, the upper limit of the temper rolling reduction ratio is set to a rolling reduction ratio at which the shape control is possible, and it is not desirable that more strain than necessary is imparted. From the viewpoint of shape control, the temper rolling reduction ratio is preferably 1.5% or less.
  • a steel sheet having desired properties specifically, a steel sheet for vitreous enameling can be obtained.
  • the enameled product according to this embodiment is obtained by processing the steel sheet according to this embodiment into a predetermined shape, then assembling the steel sheet into a product shape by welding or the like, and thereafter performing an enameling treatment thereon.
  • the enameling treatment may be performed under known conditions, and for example, a steel sheet coated with a glaze is heated to, for example, 800°C to 850°C and is held for 1 to 10 minutes to adhere the glass material of the glaze and the steel sheet to each other.
  • the rolling reduction ratio of cold rolling was changed in the ranges in Tables 3 and 4 to produce cold rolled steel sheets, and the cold rolled steel sheets were further subjected to continuous annealing at 780°C and thereafter subjected to temper rolling, thereby producing steel sheets having a sheet thickness of 0.8 mm.
  • the sheet thickness of the hot rolled steel sheets were changed with respect to the rolling reduction ratio for the cold rolling.
  • Composition (mass %) * the remainder includes Fe and impurities C Si Mn P S Al Cu O N Nb
  • Other components A1 0.0030 0.002 0.23 0.045 0.0203 0.002 0.035 0.0589 0.0032 0.001 - A2 0.0025 0.012 0.46 0.075 0.0243 0.003 0.025 0.0483 0.0028 0.002 - A3 0.0048 0.005 0.26 0.075 0.0350 0.003 0.029 0.0533 0.0032 0.001 - A4 0.0038 0.006 0.48 0.042 0.0273 0.002 0.026 0.0630 0.0028 0.003 - A5 0.0043 0.004 0.21 0.083 0.0432 0.004 0.030 0.0463 0.0027 0.001 - A6 0.0038 0.012 0.35 0.065 0.0325 0.003 0.031 0.0445 0.0032 0.003 - A7 0.0023 0.006 0.43 0.053 0.0125 0.005 0.038 0.05
  • Other components A27 0.0017 0.008 0.32 0.034 0.0181 0.005 0.040 0.0456 0.0041 0.004 - A28 0.0045 0.004 0.38 0.056 0.0245 0.004 0.032 0.0389 0.0022 0.003 Cr: 0.012, Ni: 0.023 A29 0.0029 0.002 0.24 0.046 0.0211 0.002 0.036 0.0546 0.0034 0.002 Sn: 0.007, Ca: 0.005, Sb: 0.003 A30 0.0038 0.006 0.42 0.053 0.0239 0.003 0.021 0.0466 0.0034 0.003 La: 0.052, Ce: 0.019 A31 0.0034 0.007 0.36 0.068 0.0245 0.003 0.024 0.0422 0.0024 0.001 Mo: 0.025, W: 0.007, Ta: 0.005 A32 0.0018 0.003 0.09
  • tensile strength (TS) and fracture elongation (EL) were measured by a tensile test using JIS No. 5 test pieces according to JIS Z 2241.
  • the test piece having a fracture elongation of 30% or more was evaluated as having excellent formability.
  • the steel sheet was subjected to a heat treatment that simulates enameling at a furnace temperature of 830°C for five minutes, the tensile strength was obtained by a tensile test in the above-described manner, and the ratio of the strength after the heat treatment to the strength before the heat treatment was obtained.
  • the Vickers hardness of the steel was measured before and after the heat treatment, and the ratio before and after the heat treatment was also obtained for the minimum value of the measurement result.
  • the Vickers hardnesses of five points at a thickness 1/4 position under a load of 0.98 N were measured, and the average value thereof was taken as the hardness at the measurement position. Furthermore, the above measurement was performed at 10 or more positions with intervals of 20 mm or more therebetween, and the minimum value of the measurement result (hardness) was obtained before and after the heat treatment. The ratio between the minimum values of the measurement results before and after the heat treatment was obtained.
  • the tensile strength after the enameling treatment was equal to or more than 0.85 (85%) of the tensile strength before the enameling treatment and the minimum value of hardness after the enameling treatment was equal to or more than 0.85 of the minimum value of the hardness before the enameling treatment, it was determined that the decrease in strength due to the enameling treatment can be stably suppressed.
  • the aging resistance was evaluated by the aging index.
  • the aging index is the difference in yield stress between before and after aging at 100°C for 60 minutes by applying 10% prestrain by tension using a JIS No. 5 tensile test piece. In a case where the difference in yield stress was 30 MPa or less, it was determined that the aging resistance was excellent (OK).
  • the fishscale resistance for a steel sheet which was coated with a glaze to 100 ⁇ m by a dry powder electrostatic coating method and fired at a furnace temperature of 830°C for five minutes in the air was evaluated.
  • the steel sheet after the enameling treatment was subjected to a fishscale acceleration test in which the steel sheet was put in a thermostat at 160°C for 10 hours, and the fishscale generation state was visually evaluated as four stages, A: excellent, B: slightly better, C: normal, and D: problematic. The case of D was rejected.
  • the enamel adhesion was evaluated by dropping a 2-kg weight with a spherical head from a height of 1 m on the steel sheet subjected to the enameling treatment as described above, measuring the enamel peeled state of the deformed portion with 169 contact probes, and obtaining the area ratio of the non-peeled portion.
  • the area ratio of the non-peeled portion was 40% or more, there was no problem, and when the area ratio thereof is less than 40%, the adhesion was evaluated as poor.
  • the steel sheet according to the aspect of the present invention is applied to kitchen utensils, building materials, the field of energy, and the like after being subjected to an enameling treatment
  • the steel sheet is excellent in formability, fishscale resistance after the enameling treatment, and strength properties. Therefore, the steel sheet is suitable as a steel sheet for vitreous enameling and has high industrial applicability.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
EP16844521.1A 2015-09-11 2016-09-12 Tôle d'acier et produit émaillé Withdrawn EP3348661A4 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2015179722 2015-09-11
PCT/JP2016/076847 WO2017043660A1 (fr) 2015-09-11 2016-09-12 Tôle d'acier et produit émaillé

Publications (2)

Publication Number Publication Date
EP3348661A1 true EP3348661A1 (fr) 2018-07-18
EP3348661A4 EP3348661A4 (fr) 2019-02-13

Family

ID=58239983

Family Applications (1)

Application Number Title Priority Date Filing Date
EP16844521.1A Withdrawn EP3348661A4 (fr) 2015-09-11 2016-09-12 Tôle d'acier et produit émaillé

Country Status (8)

Country Link
EP (1) EP3348661A4 (fr)
JP (1) JP6115691B1 (fr)
KR (1) KR102068499B1 (fr)
CN (1) CN107949652B (fr)
AU (1) AU2016321009C1 (fr)
MX (1) MX2018002854A (fr)
NZ (1) NZ740281A (fr)
WO (1) WO2017043660A1 (fr)

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107574375B (zh) * 2017-08-31 2019-06-07 武汉钢铁有限公司 具有优异涂搪性能的双面搪瓷用热轧酸洗钢板及其制造方法
US11236427B2 (en) 2017-12-06 2022-02-01 Polyvision Corporation Systems and methods for in-line thermal flattening and enameling of steel sheets
KR102504491B1 (ko) * 2018-05-17 2023-02-28 닛폰세이테츠 가부시키가이샤 강판 및 법랑 제품
JP7173307B2 (ja) * 2019-04-24 2022-11-16 日本製鉄株式会社 鋼板
US20230160046A1 (en) * 2020-03-27 2023-05-25 Nippon Steel Corporation Steel sheet and enameled product
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
CN114214557B (zh) * 2021-11-16 2022-10-04 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

Family Cites Families (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5126628A (en) * 1974-08-29 1976-03-05 Kawasaki Steel Co Danmenketsukan no naigokuteitansokorenchusurabu no seizoho
JPS62270727A (ja) * 1986-05-16 1987-11-25 Nippon Steel Corp 連続鋳造によるほうろう用鋼板の製造法
JPH08238544A (ja) * 1995-03-02 1996-09-17 Sumitomo Metal Ind Ltd 溶接熱影響部靭性の優れた鋼材の製造方法
JPH116031A (ja) * 1997-06-13 1999-01-12 Nkk Corp 加工性に優れ、ほうろう焼成時に軟化しにくいほうろう用冷延鋼板およびその製造方法
JPH11229087A (ja) * 1998-02-18 1999-08-24 Nkk Corp 成形性に優れたほうろう用冷延鋼板およびその製造方法
JP3421911B2 (ja) 1998-08-21 2003-06-30 Ｊｆｅエンジニアリング株式会社 焼成後強度が低下しにくいほうろう用冷延鋼板
JP3797063B2 (ja) 2000-05-02 2006-07-12 住友金属工業株式会社 耐爪飛び性、密着性、加工性が優れたほうろう用鋼板とその製造方法
JP4855163B2 (ja) * 2006-01-18 2012-01-18 新日本製鐵株式会社 ほうろう加工品
WO2007116913A1 (fr) * 2006-04-04 2007-10-18 Nippon Steel Corporation Feuille tres mince d'acier dur et son procede de fabrication
MX2009002966A (es) * 2006-09-27 2009-04-27 Nippon Steel Corp Lamina de acero esmaltada, sorprendentemente excelente en resistencia a escama de pescado y metodo para producir la misma.
CN102747309A (zh) * 2012-07-27 2012-10-24 宝山钢铁股份有限公司 一种搪瓷用钢及其制造方法
JP6586012B2 (ja) * 2013-09-10 2019-10-02 日本製鉄株式会社 ほうろう用冷延鋼板及びほうろう製品
KR101543854B1 (ko) * 2013-09-27 2015-08-11 주식회사 포스코 성형성이 우수한 법랑용 강판 및 그 제조방법
JP5713135B1 (ja) * 2013-11-19 2015-05-07 新日鐵住金株式会社 鋼板
CN104087828B (zh) * 2014-07-16 2016-05-04 武汉钢铁(集团)公司 一种热交换器用全铁素体搪瓷钢及生产方法

Also Published As

Publication number Publication date
EP3348661A4 (fr) 2019-02-13
AU2016321009A1 (en) 2018-03-15
AU2016321009C1 (en) 2019-11-21
AU2016321009B2 (en) 2019-08-22
NZ740281A (en) 2019-01-25
MX2018002854A (es) 2018-06-15
CN107949652B (zh) 2020-04-07
KR102068499B1 (ko) 2020-01-22
JP6115691B1 (ja) 2017-04-19
CN107949652A (zh) 2018-04-20
KR20180038019A (ko) 2018-04-13
WO2017043660A1 (fr) 2017-03-16
JPWO2017043660A1 (ja) 2017-09-07

Similar Documents

Publication Publication Date Title
EP3348661A1 (fr) Tôle d'acier et produit émaillé
US10011888B2 (en) Cold-rolled steel sheet for vitreous enameling and its named enameled product thereof
TWI441928B (zh) 均勻伸長和鍍覆性優異之高強度熔融鍍鋅鋼板及其製造方法
EP3196328B1 (fr) Acier émaillé possédant une trempabilité par cuisson à haute température et son procédé de fabrication
KR102504491B1 (ko) 강판 및 법랑 제품
EP3366802A1 (fr) Fil d'acier pour tréfilage
US11578391B2 (en) Nickel-containing steel for low temperature
EP3584346A1 (fr) Tôle d'acier laminée à chaud et son procédé de fabrication
EP3342893A1 (fr) Tôle d'acier plaquée de zinc fondu d'alliage et procédé de fabrication correspondant
WO2020256140A1 (fr) Fil machine
EP3702485B1 (fr) Acier comprenant du nickel pour basse température
EP3239335B1 (fr) Matériau d'acier inoxydable ferritique présentant une excellente ductilité et son procédé de production
EP3246424B1 (fr) Tôle d'acier à haute résistance et son procédé de production
JPWO2014157146A1 (ja) オーステナイト系ステンレス鋼板およびそれを用いた高強度鋼材の製造方法
CN105088101B (zh) 一种具有耐腐蚀性的搪瓷传热元件用钢及其制造方法
EP3950970A1 (fr) Tige en acier
EP3476957B1 (fr) Tôle d'acier de haute résistance recuite après galvanisation et procédé pour la fabriquer
TW202136539A (zh) 鋼板及琺瑯製品
CN113166887A (zh) 搪瓷用冷轧钢板及其制造方法
TW202006155A (zh) 鋼板
TW202024349A (zh) 鋼板及鋼板之製造方法
JP2019112696A (ja) フェライト系ステンレス鋼板およびその製造方法
JP6897878B1 (ja) 缶用鋼板およびその製造方法
JP2020152941A (ja) 二相ステンレス鋼およびその製造方法
JP2011208194A (ja) 板厚方向の材質均一性に優れた極低炭素鋼材の製造方法

Legal Events

Date Code Title Description
PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

17P Request for examination filed

Effective date: 20180316

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

AX Request for extension of the european patent

Extension state: BA ME

DAV Request for validation of the european patent (deleted)
DAX Request for extension of the european patent (deleted)
A4 Supplementary search report drawn up and despatched

Effective date: 20190115

RIC1 Information provided on ipc code assigned before grant

Ipc: C22C 38/16 20060101ALI20190109BHEP

Ipc: C22C 38/02 20060101ALI20190109BHEP

Ipc: C22C 38/06 20060101ALI20190109BHEP

Ipc: C21D 9/48 20060101ALI20190109BHEP

Ipc: C22C 38/00 20060101AFI20190109BHEP

Ipc: C22C 38/04 20060101ALI20190109BHEP

Ipc: C21D 8/02 20060101ALI20190109BHEP

Ipc: C22C 38/60 20060101ALI20190109BHEP

RAP1 Party data changed (applicant data changed or rights of an application transferred)

Owner name: NIPPON STEEL CORPORATION

GRAP Despatch of communication of intention to grant a patent

Free format text: ORIGINAL CODE: EPIDOSNIGR1

INTG Intention to grant announced

Effective date: 20200323

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

18D Application deemed to be withdrawn

Effective date: 20200804