WO2020122320A1 - Acier inoxydable ferritique à faible teneur en cr présentant une aptitude au formage et des propriétés à température élevée excellentes, et son procédé de fabrication - Google Patents

Acier inoxydable ferritique à faible teneur en cr présentant une aptitude au formage et des propriétés à température élevée excellentes, et son procédé de fabrication Download PDF

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WO2020122320A1
WO2020122320A1 PCT/KR2019/002017 KR2019002017W WO2020122320A1 WO 2020122320 A1 WO2020122320 A1 WO 2020122320A1 KR 2019002017 W KR2019002017 W KR 2019002017W WO 2020122320 A1 WO2020122320 A1 WO 2020122320A1
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high temperature
stainless steel
ferritic stainless
low
content
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Korean (ko)
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정일찬
임진우
유한진
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주식회사 포스코
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Priority to CN201980081706.6A priority Critical patent/CN113166891A/zh
Priority to JP2021532855A priority patent/JP7174853B2/ja
Priority to EP19897222.6A priority patent/EP3875627A4/fr
Publication of WO2020122320A1 publication Critical patent/WO2020122320A1/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
    • C22C38/004—Very low carbon steels, i.e. having a carbon content of less than 0,01%
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • 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
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/008—Heat treatment of ferrous alloys containing Si
    • 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
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/02—Hardening by precipitation
    • 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
    • C21D8/0205—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips of ferrous 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
    • 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
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • 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
    • C21D8/0247—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the heat treatment
    • C21D8/0273—Final recrystallisation annealing
    • 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
    • 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
    • C22C38/008—Ferrous alloys, e.g. steel alloys containing tin
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
    • 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 low-Cr ferrite-based stainless steel, and more particularly, to a low-Cr ferrite-based stainless steel capable of securing moldability while having high temperature strength and high temperature oxidation resistance.
  • Ferritic stainless steel has excellent corrosion resistance even with a small amount of expensive alloying elements, and has a higher price competitiveness than austenitic stainless steel.
  • 9 to 14% of low-Cr ferritic stainless steel is more cost-competitive, and is used in exhaust system parts (Muffler, Ex-manifold, Collector cone, etc.) corresponding to the exhaust gas temperature range of room temperature to 800°C.
  • Embodiments of the present invention by optimizing the content of Ci, Si, Sn to utilize solid solution strengthening and precipitation strengthening, without increasing the Cr content or adding Nb high temperature strength and high temperature oxidation resistance corresponding to high Cr ferritic stainless steel It is intended to provide a low-Cr ferritic stainless steel having a moldability and a method for manufacturing the same.
  • Low Cr ferritic stainless steel excellent in moldability and high temperature properties according to an embodiment of the present invention, by weight, C: 0.005 to 0.015%, N: 0.005 to 0.015%, Si: 0.5 to 1.5%, Mn: 0.1 to 0.5%, Cr: 9 to 14%, Ti: 0.1 to 0.3%, Cu: 0.3 to 0.8%, Al: 0.01 to 0.05%, Sn: 0.005 to 0.15%, including the remaining Fe and unavoidable impurities, Expressions (1) and (2) are satisfied.
  • Si, Cu, and Sn mean the content (% by weight) of each element.
  • Ni: 0.3% or less, P: 0.04% or less, and S: 0.002% or less may be further included.
  • it may include 0.03% by weight or more of the Cu precipitation phase having a size of 1 to 500 nm in the matrix structure.
  • 900 °C high temperature strength may be 12 MPa or more.
  • the elongation may be 30% or more.
  • a method of manufacturing a low-Cr ferritic stainless steel having excellent moldability and high temperature properties according to an embodiment of the present invention, by weight, C: 0.005 to 0.015%, N: 0.005 to 0.015%, Si: 0.5 to 1.5%, Mn: 0.1 to 0.5%, Cr: 9 to 14%, Ti: 0.1 to 0.3%, Cu: 0.3 to 0.8%, Al: 0.01 to 0.05%, Sn: 0.005 to 0.15%, containing the remaining Fe and unavoidable impurities
  • Si, Cu, and Sn mean the content (% by weight) of each element.
  • the cold-rolled annealed steel sheet may include 0.09% by weight or more of a Cu precipitation phase having a size of 1 to 500 nm in the matrix structure.
  • the high temperature strength of 900°C of the cold rolled annealed steel sheet may be 14.5 MPa or more.
  • the cold rolled steel sheet may satisfy the following formula (3).
  • the low-Cr ferritic stainless steel according to the embodiment of the present invention can increase the high-temperature strength by 30% or more compared to the existing by distributing the fine Cu precipitation phase at the same time as the solid solution strengthening effect of Si and Cu, and the surface thickening of Si and Sn Thereby, high temperature oxidation resistance can also be improved.
  • the high temperature strength characteristics may be more excellent.
  • 1 is a graph showing the correlation between high temperature properties according to equations (1) and (3) of the present invention.
  • Low Cr ferritic stainless steel excellent in moldability and high temperature properties according to an embodiment of the present invention, by weight, C: 0.005 to 0.015%, N: 0.005 to 0.015%, Si: 0.5 to 1.5%, Mn: 0.1 to 0.5%, Cr: 9 to 14%, Ti: 0.1 to 0.3%, Cu: 0.3 to 0.8%, Al: 0.01 to 0.05%, Sn: 0.005 to 0.15%, including the remaining Fe and unavoidable impurities, Expressions (1) and (2) are satisfied.
  • Si, Cu, and Sn mean the content (% by weight) of each element.
  • the present inventors have obtained various findings as a result of various studies to improve high temperature strength and high temperature oxidation resistance of low cost low Cr ferritic stainless steel.
  • Nb is added to the ferritic stainless steel for exhaust system for high temperature strength, and Nb is not a preferred development direction because the raw material cost is relatively high and causes the manufacturing cost to increase.
  • substituted solid solution strengthening elements are effective to increase high temperature strength. Particularly, when a substituted solid solution strengthening element is added, the larger the difference in weight and atomic radius compared to Fe and Cr, the greater the solid solution strengthening effect.
  • alloy elements such as Si, Cu, Sn, etc. are located far away from Fe and Cr, and because there are differences in weight and atomic radius, it is judged that it can be substituted for the existing Nb, and component optimization was performed to increase the high temperature strength. .
  • the Cr content is generally increased, but Cr is also not a desirable development direction because the raw material cost is high and causes the manufacturing cost to increase.
  • certain elements when exposed to high temperature for a long time, certain elements must be densely concentrated on the surface to suppress the formation of Fe-oxide film.
  • Si, Cu, and Sn candidates were selected as elements that can be concentrated on the surface, and component optimization was performed for high temperature oxidation resistance.
  • the present invention must satisfy the component system conditions and equations as follows.
  • Low Cr ferritic stainless steel excellent in moldability and high temperature properties according to an embodiment of the present invention, by weight, C: 0.005 to 0.015%, N: 0.005 to 0.015%, Si: 0.5 to 1.5%, Mn: 0.1 to 0.5%, Cr: 9 to 14%, Ti: 0.1 to 0.3%, Cu: 0.3 to 0.8%, Al: 0.01 to 0.05%, Sn: 0.005 to 0.15%, remaining Fe and unavoidable impurities.
  • the content of C is 0.005 to 0.015%.
  • the content of N is 0.005 to 0.015%.
  • the concentration of N in the steel exceeds 0.015%, the concentration of solid solution N reaches the limit, and it combines with Cr, and a Cr 2 N precipitate is generated, thereby deteriorating the high temperature oxidation resistance due to local Cr depletion in the base.
  • the content of N is limited to the range of 0.005 to 0.015%.
  • the content of Si is 0.5 to 1.5%.
  • Si is a solid solution strengthening element for increasing the high temperature strength, and at the same time, a Si-rich oxide film is formed on the surface layer to increase the high temperature oxidation resistance.
  • Si content is limited as above.
  • the content of Mn is 0.1 to 0.5%.
  • Mn is an imperative that is inevitably contained in steel, and serves to stabilize austenite.
  • Mn content in the low-Cr ferritic stainless steel exceeds 0.5%, austenite reverse transformation occurs during annealing after hot rolling or cold rolling, which adversely affects elongation. Therefore, the content of Mn is limited as above.
  • the content of Cr is 9 to 14%.
  • Cr is an essential element added in the formation of an anti-oxidative passivation film in stainless steel.
  • the Cr content should be added more than 9%.
  • the present invention is intended to develop a low-cost steel with reduced Cr, so the upper limit is limited to 14%. More preferably, it may range from 10.5 to 12.5%.
  • the content of Ti is 0.1 to 0.3%.
  • Ti must be added at least 0.1% in order to increase the corrosion resistance of the weld. Ti combines with C and N to form Ti(C,N) precipitates to lower the amount of solid solution C and N, and serves to suppress the formation of Cr depletion layer. However, when the Ti content exceeds 0.3%, the Ti component in the surface layer reacts with oxygen to cause yellow discoloration. Therefore, the Ti content is limited as above.
  • the content of Cu is 0.3 to 0.8%.
  • Cu is a solid solution strengthening element that replaces Nb and contributes to high temperature strength.
  • Cu when Cu generates fine precipitates through appropriate heat treatment, it can be expected that additional high-temperature strength increases due to the precipitation strengthening effect. Therefore, 0.5% or more is added. However, if too much Cu is added, the high temperature hot workability may be impaired, so the amount is limited to 0.8% or less.
  • the content of Al is 0.01 to 0.05%.
  • Al is an element added for deoxidation during steelmaking operations.
  • Al content exceeds 0.05%, Al in the surface layer reacts with oxygen to form a non-uniform oxide layer, which adversely affects high temperature oxidation resistance. Therefore, the Al content is limited as above.
  • the content of Sn is 0.005 to 0.15%.
  • Sn is a solid solution strengthening element for increasing high temperature strength, and at the same time, forming a Sn-rich oxide film on the surface layer increases the high temperature oxidation resistance.
  • a minimum Sn content of at least 0.005% should be added.
  • the upper limit of the Sn content is limited to 0.15% or less.
  • Ni: 0.3% or less, P: 0.04% or less, and S: 0.002% or less may be further included.
  • Ni is 0.3% or less.
  • Ni may contain 0.01% or more as an imperatively contained impurity in the steel, and serves to stabilize austenite.
  • austenite reverse transformation occurs during annealing heat treatment after hot rolling or cold rolling, which adversely affects elongation. Therefore, the content of Ni is limited as above.
  • P The content of P is 0.04% or less.
  • P is an unavoidable impurity contained in the steel, so it causes grain boundary corrosion during pickling or inhibits hot workability, so its content is adjusted to 0.04% or less.
  • S The content of S is 0.002% or less.
  • S is an unavoidable impurity contained in the steel and is segregated at the grain boundaries, hindering the hot workability, so its content is limited to 0.002% or less.
  • the rest of the ferritic stainless steel excluding the alloy elements described above, is made of Fe and other unavoidable impurities.
  • the low-Cr ferritic stainless steel excellent in moldability and high temperature characteristics according to an embodiment of the present invention may satisfy the following formulas (1) to (3).
  • High temperature strength is usually affected by solid solution strengthening and precipitation strengthening.
  • Cu and Si are representative solid solution strengthening elements, so it is preferable to add them to increase the high temperature strength.
  • the high temperature strength is increased more effectively due to the precipitation strengthening effect.
  • the Si content is increased, Cu has a lower solid solubility limit, so that precipitation of the Cu precipitation phase becomes easier. Accordingly, it is possible to deposit 0.03% by weight or more of the Cu precipitation phase having a size of 1 to 500 nm in the matrix structure. Therefore, the Cu+Si content is controlled in a range of 1.3% or more.
  • the low Cr ferritic stainless steel according to the present invention may exhibit a high temperature strength at 900°C of 12 MPa or more.
  • Si, Cu, and Sn alloy elements each have a positive effect on high temperature strength or high temperature oxidation resistance, but the material is too hard, resulting in poor elongation and poor formability.
  • the elongation of 30% or more can be secured to prevent the moldability deterioration. Therefore, in order to secure material processability, the relationship between Si, Cu, and Sn contents is controlled in the above range.
  • the method of manufacturing a low-Cr ferritic stainless steel excellent in moldability and high temperature characteristics of the present invention can be manufactured as a cold rolled steel sheet through a normal manufacturing process, and includes the above-described alloy component composition and satisfies equations (1) to (3). Cold-annealing the ferritic stainless steel cold-rolled steel sheet; And rapidly cooling to a temperature range of 450 to 550°C to maintain for 5 minutes or more.
  • a slab containing the above-described alloy component composition may be hot-rolled, annealed and heat-treated by hot-rolled hot-rolled steel sheet, and cold-rolled to produce a cold-rolled steel sheet.
  • the cold rolled steel sheet can be maintained for at least 5 minutes by quenching to a temperature range of 450 to 550° C. after a normal recrystallization heat treatment in the cold rolling annealing process. Through the cooling and maintenance, precipitation of a Cu precipitation phase in the same component system can be increased, and high temperature strength can be further improved.
  • the cold-rolled annealed steel sheet may include 0.09% by weight or more of a Cu precipitation phase having a size of 1 to 500 nm in the matrix structure, and a high temperature strength of 900°C may be 14.5 MPa or more.
  • a 20 mm bar sample was prepared with the alloy component meter shown in Table 1 below by utilizing a stainless steel lab scale melting and ingot production facility. After reheating at 1,200°C, hot rolling was performed to 6 mm, followed by hot rolling annealing at 1,100°C, cold rolling to 2.0 mm, and annealing heat treatment at 1,100°C. After heat treatment only for some invention examples, it was quenched to 500° C., held for about 7 minutes, and then air-cooled to produce cold-rolled annealed steel sheets.
  • the fraction of Cu precipitation phase was measured for each cold rolled annealed steel sheet, and it was confirmed whether discoloration occurred after 1 hour at 500°C. In addition, it was shown in Table 2 by measuring the high temperature strength at 900 °C and elongation at room temperature.
  • Comparative Examples 1 to 3 the content of Si and Sn was less than that of the Ti content, so the formula (3) was unsatisfactory, and high-temperature discoloration occurred because the Si and Sn-rich oxide films on the surface layer were not sufficiently formed.
  • Comparative Example 4 since the Cu content was low and the Si content was high, the expression (3) was satisfied, so no discoloration occurred, and it was confirmed that the high temperature oxidation resistance according to the expression (3) was secured.
  • Inventive Example 1 satisfies the component system composition of the present invention and equations (1) and (2). Discoloration occurred at a high temperature, but satisfying Equation (1), a Cu precipitate precipitated 0.05% by weight and showed a high temperature strength of 12 MPa or more. In addition, it was confirmed that the elongation was measured to be 33.3% while ensuring high temperature strength by satisfying Equation (2), and thus excellent moldability.
  • Inventive Examples 2 to 4 optimized Si, Cu, and Sn contents to satisfy all of the formulas (1) to (3), thus exhibiting high temperature strength of 13.5 MPa or higher and elongation of 30.8% or higher, and high temperature discoloration did not occur.
  • Inventive Examples 5 to 7 show that not only the formulas (1) to (3) were satisfied by optimizing the contents of Si, Cu, and Sn, but a cooling schedule was applied after heat treatment according to the present invention.
  • the elongation was secured to 30.3% or more, and as a result of rapid quenching and holding time after heat treatment, a fine Cu precipitated phase precipitated more than 0.09% by weight, and the high temperature strength was higher than 14.6 MPa.
  • Inventive Examples 5 and 6 exhibited high temperature strength of 15 MPa or more.
  • 1 is a graph showing the values of equations (1) and (3) of the embodiments according to the present invention. 1, it can be confirmed the correlation of the equations (1) and (3) for high temperature strength and high temperature oxidation resistance.
  • the ferritic stainless steel according to the present invention can increase the high temperature characteristics of existing steel types by 30% or more without increasing Cr content and adding Nb, thereby reducing raw material costs.

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Abstract

Acier inoxydable ferritique à faible teneur en Cr ayant une aptitude au formage et des propriétés à température élevée excellentes, et son procédé de fabrication. Des modes de réalisation de la présente invention peuvent fournir : de l'acier inoxydable ferritique à faible teneur en Cr, qui a une résistance à température élevée et une résistance à l'oxydation à température élevée excellentes et garantit une aptitude au formage, correspondant à de l'acier inoxydable ferritique à teneur élevée en Cr sans augmentation de la quantité de Cr ni ajout de Nb, par l'optimisation des quantités de Ci, Si et Sn et l'utilisation d'un renforcement de solution solide et d'un renforcement de précipitation ; et son procédé de fabrication.
PCT/KR2019/002017 2018-12-10 2019-02-20 Acier inoxydable ferritique à faible teneur en cr présentant une aptitude au formage et des propriétés à température élevée excellentes, et son procédé de fabrication WO2020122320A1 (fr)

Priority Applications (3)

Application Number Priority Date Filing Date Title
CN201980081706.6A CN113166891A (zh) 2018-12-10 2019-02-20 具有优异的可成型性和高温特性的低Cr铁素体不锈钢及其制造方法
JP2021532855A JP7174853B2 (ja) 2018-12-10 2019-02-20 成形性及び高温特性に優れた低Ｃｒフェライト系ステンレス鋼及びその製造方法
EP19897222.6A EP3875627A4 (fr) 2018-12-10 2019-02-20 Acier inoxydable ferritique à faible teneur en cr présentant une aptitude au formage et des propriétés à température élevée excellentes, et son procédé de fabrication

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CN113166891A (zh) 2021-07-23
EP3875627A4 (fr) 2022-03-16
JP7174853B2 (ja) 2022-11-17
KR102168829B1 (ko) 2020-10-22
KR20200071212A (ko) 2020-06-19
JP2022513747A (ja) 2022-02-09

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