WO2020054540A1 - Acier inoxydable à base de martensite de type à durcissement par précipitation et élément de forage d'excavation souterrain - Google Patents

Acier inoxydable à base de martensite de type à durcissement par précipitation et élément de forage d'excavation souterrain Download PDF

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Publication number
WO2020054540A1
WO2020054540A1 PCT/JP2019/034788 JP2019034788W WO2020054540A1 WO 2020054540 A1 WO2020054540 A1 WO 2020054540A1 JP 2019034788 W JP2019034788 W JP 2019034788W WO 2020054540 A1 WO2020054540 A1 WO 2020054540A1
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WIPO (PCT)
Prior art keywords
mass
amount
stainless steel
less
martensitic stainless
Prior art date
Application number
PCT/JP2019/034788
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English (en)
Japanese (ja)
Inventor
晃彦 岡本
宏之 高林
伸幸 ▲高▼橋
Original Assignee
大同特殊鋼株式会社
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
Priority claimed from JP2019147851A external-priority patent/JP7298382B2/ja
Application filed by 大同特殊鋼株式会社 filed Critical 大同特殊鋼株式会社
Publication of WO2020054540A1 publication Critical patent/WO2020054540A1/fr

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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
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40—Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/50—Ferrous alloys, e.g. steel alloys containing chromium with nickel 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
    • C21D6/00—Heat treatment 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

Definitions

  • SUS630 uses Cu as a main hardening element, but shows relatively low yield strength.
  • alloys using Al or Ti as a hardening element for example, PH13-8Mo, Custom450, etc.
  • Patent Document 1 In mass%, C: ⁇ 0.2%, 7% ⁇ Ni ⁇ 14%, 0% ⁇ Co ⁇ 3.5%, 9.5% ⁇ Cr ⁇ 14%, 0.5% ⁇ Mo ⁇ 3%, 0.25% ⁇ Al ⁇ 1%, and 0.75% ⁇ Ti ⁇ 2.5%, with the balance being Fe and impurities, (B) A precipitation-strengthened stainless steel satisfying a predetermined relational expression is disclosed.
  • Patent Document 3 states that (A) When the composition is weight%, 9% ⁇ Cr ⁇ 13%, 1.5% ⁇ Mo ⁇ 3%, 8% ⁇ Ni ⁇ 14%, 1% ⁇ Al ⁇ 2%, and Al + Ti ⁇ 2.25% Under the conditions of 0.5% ⁇ Ti ⁇ 1.5%, measurement limit value ⁇ Co ⁇ 2%, Mo + (W / 2) ⁇ 3%, measurement limit value ⁇ W ⁇ 1%, measurement limit value ⁇ P ⁇ 0.02%, measurement limit value ⁇ S ⁇ 0.0050%, measurement limit value ⁇ N ⁇ 0.0060%, measurement limit value ⁇ C ⁇ 0.025%, measurement limit value ⁇ Cu ⁇ 0.5% , Measurement limit ⁇ Mn ⁇ 3%, measurement limit ⁇ Si ⁇ 0.25%, measurement limit ⁇ O ⁇ 0.0050%, and (B) A martensitic stainless steel satisfying a predetermined relational expression is disclosed. The document describes that such martensitic stainless steel is excellent in corrosion resistance, strength, and tough
  • precipitation-hardening martensitic stainless steels require a further balance of strength and toughness.
  • a drill component for underground excavation, a high-strength fastener, and the like are required to have a tensile strength of ⁇ 1550 MPa and an impact value of ⁇ 30 J / cm 2 .
  • the strength is affected by the type and amount of the precipitate.
  • intermetallic compounds are actively used for increasing strength.
  • toughness is also presumed to be related to the type and amount of precipitates, but details are not disclosed.
  • Si acts as a deoxidizing agent. If the amount of Si is too small, deoxidation at the time of dissolution will be insufficient, and the cleanliness will decrease. Therefore, the amount of Si needs to be 0.01 mass% or more. On the other hand, when the amount of Si becomes excessive, oxide inclusions are formed, and toughness is reduced. Therefore, the amount of Si needs to be 0.10 mass% or less.
  • the Cr also contributes to the adjustment of the Ms point, and the smaller the Cr amount, the higher the Ms point. Therefore, the smaller the Cr content, the smaller the retained austenite after the solution heat treatment or the sub-zero treatment. This also improves the homogeneity of the microstructure and improves the 0.2% proof stress. Conversely, as the amount of Cr increases, the Ms point decreases, so the amount of retained austenite increases. On the other hand, when the Cr content is excessive, the residual austenite content before the aging treatment is excessive, and the 0.2% proof stress is reduced. Further, when the Cr content is excessive, a ⁇ ferrite phase is easily formed. Therefore, the amount of Cr needs to be 10.9 mass% or less. The amount of Cr is preferably 10.0 mass% or less, and more preferably 9.5 mass% or less.
  • Nb is, like Al and Ti, Ni and an intermetallic compound (Ni (Al, Nb), Ni 3 (Ni or Al 3 in Ni 3 (Al, Ti) in which part of Al or Ti is substituted with Nb)).
  • Al, Ti, Nb)) to contribute to the improvement of the strength of the base material.
  • Nb forms carbonitrides and contributes to the refinement of crystal grains. Therefore, Nb can be added as needed.
  • the amount of Nb is excessive, carbonitrides increase and the toughness decreases. When the Nb content is excessive, a ⁇ ferrite phase is easily formed. Therefore, the Nb amount needs to be less than 0.50 mass%.
  • the Nb amount is preferably 0.40 mass% or less, more preferably 0.30 mass% or less.
  • the precipitation-hardening martensitic stainless steel according to the present invention satisfies the following equations (1) to (4) in addition to the main constituent elements being in the above-described range.
  • Ni eq [Ni] +0.11 [Mn] -0.0086 [Mn] 2 +0.44 [Cu] +18.4 [N] +24.5 [C]
  • Cr eq [Cr] +1.21 [Mo] +0.48 [Si] +2.2 [Ti] +2.48 [Al]
  • [X] represents the content (mass%) of the element X.
  • Equation (1) represents the range of the total amount of Al, Ti, and Nb. As the total amount of these elements increases, B2 phase (NiAl), eta phase (Ni 3 (Al, Ti) , Ni 3 (Al, Ti, Nb)) precipitation amount of intermetallic compounds such as increased strength improvement To contribute. Further, by adding Al and Ti in combination, precipitates of both the B2 phase and the ⁇ phase are formed, which contributes to improvement in strength and toughness. In order to obtain such an effect, the total amount of these elements needs to be 1.00 mass% or more. The total amount is preferably 1.10 mass% or more, and more preferably 1.20 mass% or more.
  • Ni eq In order to obtain a precipitation-hardened martensitic stainless steel having excellent strength and toughness, Ni eq needs to be 10.00 or more. Ni eq is preferably at least 11.50, and more preferably at least 13.00. On the other hand, when Ni eq becomes excessive, the retained austenite before the aging treatment increases, and the strength decreases. Therefore, Ni eq needs to be 17.00 or less. Ni eq is preferably 16.50 or less, more preferably 15.50 or less.
  • Creq is required to be 17.00 or less. Creq is preferably 16.50 or less, more preferably 15.50 or less.
  • Precipitation hardening type martensitic stainless steel according to the present invention, (A) melting and casting a raw material blended to have a predetermined composition; (B) performing a homogenizing heat treatment on the obtained ingot, (C) hot forging the material after the homogenization heat treatment, (D) A solution heat treatment is performed on the hot forged material, (E) Sub-zero treatment is performed on the solution after solution heat treatment as necessary, (F) It can be manufactured by subjecting the material after the sub-zero treatment to an aging treatment.
  • a homogenization heat treatment is performed on the obtained ingot.
  • the homogenization heat treatment is performed to remove segregation generated during casting.
  • the conditions for the homogenizing heat treatment are not particularly limited as long as such effects are exhibited.
  • the homogenization heat treatment is performed by heating and maintaining the ingot under the conditions of a temperature of 1150 to 1240 ° C. and a time of 10 hr or more.
  • aging processing is performed on the material after the sub-zero processing.
  • the aging treatment is performed to precipitate an intermetallic compound phase such as a B2 phase and an ⁇ phase in the mother phase.
  • the condition of the aging treatment is not particularly limited as long as such an effect is exerted.
  • the aging treatment is performed by heating the material at 400 to 600 ° C. for 1 to 24 hours. After the heat treatment, cooling is performed by air cooling.
  • the drill part for underground drilling according to the present invention is made of the precipitation hardening martensitic stainless steel according to the present invention.
  • the details of the precipitation hardening type martensitic stainless steel are as described above, and thus the description is omitted.
  • Precipitation hardened martensitic stainless steel is a material having excellent strength, toughness, and corrosion resistance, but it is known that it is difficult to balance strength and toughness.
  • high strength is achieved mainly by adding reinforcing elements such as Cu and Al.
  • simply adding an excessive amount of a strengthening element improves the strength properties but significantly lowers the toughness.
  • the strength and toughness of the matrix can be improved while maintaining the corrosion resistance of the matrix at an appropriate level.
  • an appropriate amount of Al and an appropriate amount of Ti are simultaneously added to the precipitation hardening type martensitic stainless steel in which the Cr amount and the Ni amount are optimized, the strength and the toughness are further improved while maintaining the appropriate corrosion resistance. be able to.
  • B2 phase and (NiAl) believed to be due to a composite reinforced by 2-phase ⁇ phase (Ni 3 Ti).
  • Examples 1 to 16, Comparative Examples 1 to 8) [1. Preparation of sample]
  • 50 kg of steel having the composition shown in Table 1 was melted and ingot.
  • a homogenizing heat treatment was performed under the conditions of 1200 ° C. ⁇ 24 hours and air cooling.
  • a round bar having a diameter of 24 mm was forged under the conditions of a start temperature of 1200 ° C. and an end temperature of 900 ° C., and then air-cooled.
  • each steel ingot was subjected to solution heat treatment under the conditions of 1000 ° C. ⁇ 1 hr and water cooling.
  • a sub-zero treatment was performed under the condition of ⁇ 76 ° C. ⁇ 6 hours.
  • aging treatment was performed under the condition of 530 ° C. ⁇ 4 hours and air cooling.
  • Test method [2.1. Tensile test (measurement of 0.2% proof stress)] A tensile test was performed according to a metal tensile test method specified in ASTM A370, and a 0.2% proof stress was measured. [2.2. Charpy impact test] A 2 mm V notch test piece was sampled so that the longitudinal direction coincided with the forging direction. Using this test piece, impact characteristics (absorbed energy) were measured in accordance with ASTM A370 standard. The test temperature was room temperature.
  • Comparative Example 1 has a high 0.2% proof stress (> 1400 MPa) but a low toughness ( ⁇ 10 J) due to an excessive amount of C.
  • Comparative Example 2 since the amount of Al + Ti + Nb is excessive, there are many precipitates. Therefore, the 0.2% proof stress is high (> 1400 MPa), but the toughness is low ( ⁇ 10 J).
  • Comparative Example 3 shows a moderate 0.2% proof stress (1300 to 1400 MPa) due to a small amount of Ti, but has low toughness ( ⁇ 10 J). This is presumably because the effect of the combined precipitation of the B2 phase and the ⁇ phase is not sufficiently exhibited due to the small amount of Ti.
  • Comparative Example 7 has a high 0.2% proof stress (> 1400 MPa) but a low toughness ( ⁇ 10 J) because the amount of Cr and the amount of Cr eq are also excessive. This is presumably because a ⁇ ferrite phase was formed.
  • Comparative Example 8 since the amount of Ni and the amount of Ni eq were small, it was broken before exhibiting 0.2% proof stress, and the toughness was low ( ⁇ 10 J).

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Steel (AREA)

Abstract

L'invention concerne un acier inoxydable à base de martensite de type à durcissement par précipitation et un foret d'excavation souterrain utilisant ledit acier inoxydable, contenant C < 0,10 % en masse, 0,01 ≤ Si ≤ 0,10 % en masse, 0,01 ≤ Mn ≤ 0,10 % en masse, P ≤ 0,010 % en masse, S ≤ 0,010 % en masse, 10,0 ≤ Ni ≤ 16,0 % en masse, 8,0 ≤ Cr ≤ 10,9 % en masse, 1,0 ≤ Mo ≤ 2,5 % en masse, 0,001 ≤ N ≤ 0,010 % en masse, 0,40 ≤ Al ≤ 1,40 % en masse, Cu < 0,10 % en masse, 0,30 ≤ Ti ≤ 1,40 % en masse et 0 ≤ Nb ≤ 0,50 % en masse, la partie restante étant du Fe et des impuretés inévitables, 1,00 ≤ [Al] + [Ti] + [Nb] ≤ 2,00, 5,50 ≤ [Ni]/ ([Al] + [Ti] + [Nb]) ≤ 12,00, 10,00 ≤ Nieq≤17,00 et 12,00 ≤ Creq≤17,00 étant satisfaits.
PCT/JP2019/034788 2018-09-13 2019-09-04 Acier inoxydable à base de martensite de type à durcissement par précipitation et élément de forage d'excavation souterrain WO2020054540A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
JP2018-171958 2018-09-13
JP2018171958 2018-09-13
JP2019147851A JP7298382B2 (ja) 2018-09-13 2019-08-09 析出硬化型マルテンサイト系ステンレス鋼及び地下掘削用ドリル部品
JP2019-147851 2019-08-09

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WO2020054540A1 true WO2020054540A1 (fr) 2020-03-19

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024013542A1 (fr) * 2022-07-12 2024-01-18 Arcelormittal Acier laminé à chaud et son procédé de fabrication

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101050509A (zh) * 2007-05-17 2007-10-10 钢铁研究总院 高强高韧马氏体时效不锈钢
WO2012002208A1 (fr) * 2010-06-28 2012-01-05 社団法人日本航空宇宙工業会 Acier inoxydable durci par précipitation et son procédé de production
JP2013147698A (ja) * 2012-01-19 2013-08-01 Hitachi Ltd 析出硬化型マルテンサイト系ステンレス鋼、それを用いた蒸気タービン長翼、蒸気タービン、発電プラント
JP2013209742A (ja) * 2012-02-27 2013-10-10 Hitachi Ltd 蒸気タービンロータ
JP2018524473A (ja) * 2015-07-16 2018-08-30 サンドビック インテレクチュアル プロパティー アクティエボラーグ 新規のマルテンサイト系ステンレス鋼

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101050509A (zh) * 2007-05-17 2007-10-10 钢铁研究总院 高强高韧马氏体时效不锈钢
WO2012002208A1 (fr) * 2010-06-28 2012-01-05 社団法人日本航空宇宙工業会 Acier inoxydable durci par précipitation et son procédé de production
JP2013147698A (ja) * 2012-01-19 2013-08-01 Hitachi Ltd 析出硬化型マルテンサイト系ステンレス鋼、それを用いた蒸気タービン長翼、蒸気タービン、発電プラント
JP2013209742A (ja) * 2012-02-27 2013-10-10 Hitachi Ltd 蒸気タービンロータ
JP2018524473A (ja) * 2015-07-16 2018-08-30 サンドビック インテレクチュアル プロパティー アクティエボラーグ 新規のマルテンサイト系ステンレス鋼

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024013542A1 (fr) * 2022-07-12 2024-01-18 Arcelormittal Acier laminé à chaud et son procédé de fabrication

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