EP2157196A1 - Procédé de traitement d'acier maraging - Google Patents

Procédé de traitement d'acier maraging Download PDF

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Publication number
EP2157196A1
EP2157196A1 EP09251975A EP09251975A EP2157196A1 EP 2157196 A1 EP2157196 A1 EP 2157196A1 EP 09251975 A EP09251975 A EP 09251975A EP 09251975 A EP09251975 A EP 09251975A EP 2157196 A1 EP2157196 A1 EP 2157196A1
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EP
European Patent Office
Prior art keywords
maraging steel
workpiece
aging
temperature
processing
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.)
Ceased
Application number
EP09251975A
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German (de)
English (en)
Inventor
Gopal Daz
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.)
RTX Corp
Original Assignee
United Technologies 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 United Technologies Corp filed Critical United Technologies Corp
Publication of EP2157196A1 publication Critical patent/EP2157196A1/fr
Ceased legal-status Critical Current

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    • 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
    • C21D6/001—Heat treatment of ferrous alloys containing Ni
    • 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
    • C21D6/007—Heat treatment of ferrous alloys containing Co
    • 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
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/10—Ferrous alloys, e.g. steel alloys containing cobalt
    • C22C38/105—Ferrous alloys, e.g. steel alloys containing cobalt containing Co and Ni

Definitions

  • This disclosure relates to maraging steel and, more particularly, to an economic method of processing maraging steel to achieve improved mechanical properties.
  • Maraging steel grades are generally regarded as high strength steels that do not include carbon.
  • the high strength is obtained through thermal processing to form a predominantly martensitic microstructure.
  • maraging steels are typically solution annealed at a temperature sufficient to form an austenite phase and then cooled to room temperature to transform the austenite phase into the martensitic phase.
  • solution annealing steps are typically used to provide a homogenous microstructure.
  • the maraging steel may subsequently be aged at a lower temperature to precipitation harden the maraging steel.
  • the disclosed methods of processing a workpiece of maraging steel are intended to provide economic processing and improved mechanical properties.
  • a method of processing includes receiving a workpiece of maraging steel that has been subjected to thermomechanical processing at an austenite solutionizing temperature and directly aging the workpiece of maraging steel at an aging temperature to form precipitates within a microstructure of the workpiece of maraging steel, without any intervening heat treatments between a thermomechanical processing and the direct aging.
  • the method may include thermomechanically processing the workpiece of maraging steel at the austenite solutionizing temperature prior to directly aging the workpiece of maraging steel.
  • a method in another aspect, includes processing a workpiece of maraging steel that has been subjected to thermomechanical processing at an austenite solutionizing temperature to thereby produce a component of maraging steel.
  • the workpiece of maraging steel is directly aged at an aging temperature to form precipitates within the microstructure of the workpiece of maraging steel and establish an ultimate tensile strength of the component of maraging steel that is greater than 265 ksi (1.83 GPa), without any intervening heat treatments between the thermomechanical processing and the direct aging.
  • Figure 1 illustrates an example method 20 of processing a workpiece of maraging steel 22 (see Figure 2 ).
  • the disclosed workpiece of maraging steel 22 may have any form, such as a sheet, ingot, or casting.
  • the method 20 may be used to economically process the workpiece of maraging steel 22 to provide improved properties.
  • the workpiece of maraging steel 22 is formed of a maraging steel alloy composition.
  • the maraging steel alloy composition includes 17wt%-19wt% of nickel, 8wt%-12wt% of cobalt, 3wt%-5wt% of molybdenum, 0.2wt%-1.7wt% of titanium, 0.05wt%-0.15wt% of aluminum, and a balance of iron.
  • the composition may vary from the given example composition.
  • the given composition consists essentially of the given elements and impurities that do not affect the properties of the alloy or elements that are unmeasured or undetectable in the alloy.
  • the alloy generally does not include carbon, but may include up to about 0.03wt% of carbon as an impurity.
  • the maraging steel alloy may also be classified by composition, such as by commonly used designations M200, M250, M300, or M350.
  • the example method 20 includes a thermomechanical processing step 24 that includes working (e.g., plastically deforming) the workpiece of maraging steel 22 at an austenite solutionizing temperature.
  • the process of working may include any suitable type of process, such as rolling, forging, or any forming process.
  • the austenite solutionizing temperature may depend somewhat on the selected composition of the maraging steel. However, in most instances, the austenite solutionizing temperature will be 1500°F - 1750°F (816oC - 954oC) to solutionize the compositional components of the maraging steel into a gamma austenite phase microstructrue.
  • the workpiece of maraging steel 22 may be subjected to the austenite solutionizing temperature for the duration of the working process.
  • the thermomechanical processing step 24 also includes cooling the workpiece of maraging steel 22 from the austenite solutionizing temperature to transform the gamma austenite phase to an alpha martensite phase.
  • the workpiece of maraging steel 22 may be cooled to a temperature below the austenite solutionizing temperature, such as ambient (approximately 72°F or 22°C). However, other cooling temperatures may be selected.
  • the workpiece of maraging steel 22 is subjected to a direct aging step 26.
  • the direct aging step 26 includes heat treating the workpiece of maraging steel 22 at an aging temperature to form precipitates within the martensitic microstructure.
  • the term "direct aging” refers to aging the workpiece of maraging steel 22 without conducting any intervening heat treatments between the thermomechanical processing step 24 and the direct aging step 26.
  • any processing that occurs between the thermomechanical processing step 24 and the direct aging step 26 is conducted at temperatures no greater than room temperature (approximately 72oF or 22oC).
  • thermomechanical processing step 24 any processing that occurs between the thermomechanical processing step 24 and the direct aging step 26 is conducted at temperatures no greater than the aging temperature of the direct aging step 26. Therefore, relative to any heat treatments, the workpiece of maraging steel 22 proceeds directly from the thermomechanical processing step 24 to the direct aging step 26.
  • the direct aging step 26 may be conducted at any suitable aging temperature and for any suitable amount of time, depending upon the desired end mechanical properties of the workpiece of maraging steel 22 and the material composition.
  • the aging temperature may be 850°F - 950°F (454°C - 510°C).
  • the direct aging step 26 includes heating the workpiece of maraging steel 22 at a temperature of about 900°F (482°C) for about nine hours to precipitation strengthen the martensitic microstructure.
  • the aging time may vary depending on the desired degree of precipitation.
  • thermomechanical processing step 24 and the direct aging step 26 of the method 20 need not be conducted serially. That is, the thermomechanical processing step 24 may be conducted at one facility or site, and the direct aging step 26 may be conducted at another facility or site. Thus, from the perspective of a single processor, the thermomechanical processing step 24 of the method 20 may be regarded as receiving the workpieces of maraging steel 22 that have already been thermomechanically processed, and subsequently conducting the direct aging step 26.
  • processing the workpiece of maraging steel 22 according to the examples disclosed herein provides desirable mechanical properties compared with control specimens that are solution heat treated between thermomechanical processing and aging. That is, the control specimens include an additional step of heat treating compared to the example method 20.
  • the workpiece of maraging steel 22 (Directly Aged Specimen) processed according to method 20 provides a higher 0.2% yield strength and ultimate tensile strength than the control specimen.
  • the % elongation of the workpiece of maraging steel 22 is somewhat lower than the control specimen; however, for some end uses the loss of elongation may not be a significant factor.
  • the hardness of the directly aged workpiece of maraging steel 22 and the control specimen are each between about 56-58 Rc.
  • thermomechanical processing step 34 may include any type of thermomechanical processing, such as rolling 36, forging 38, or other forming process.
  • the rolling 36 or forging 38 may be conducted at the austenite solutionizing temperature.
  • the workpiece of maraging steel 22 is a cast form that is then forged into an ingot using the forging 38 process or rolled into a sheet using the rolling 36 process.
  • the workpiece of maraging steel 22 is subjected to the direct aging step 26 in a chamber 40 at an appropriate aging temperature for a predetermined amount of time.
  • the direct aging step 26 may be aged in the chamber 40 at the same time.
  • the workpiece of maraging steel 22 is removed from the chamber 40 and allowed to cool in air for example to a temperature less than 850°F (454°C), such as room temperature. Once cooled, the workpiece of maraging steel 22 may be considered to be a component of maraging steel 42.
  • the component of maraging steel 42 may be subjected additional processes to produce an end component, such as finishing, coating, etc.
  • Figure 3 schematically illustrates a cross-section of a portion of the component of maraging steel 42 that has been polished and etched to reveal a microstructure.
  • the component of maraging steel 42 has undergone the thermomechanical processing step 24 and the direct aging step 26 as described above.
  • the microstructure includes martensitic grains 50 having an average ASTM grain size of 10.
  • ASTM grain size may be determined according to ASTM E112.
  • the microstructure includes precipitates 52 (e.g., Ni3Mo and Ni3Ti) near the grain boundaries of the martensitic grains 50.
  • the precipitates 52 are formed during the direct aging step 26 as elements from the composition that precipitate out of solution as intermetallic particles.
  • the precipitates 52 generally function to strengthen the component of maraging steel 42.
  • the size of the grains 50 and the presence of the precipitates 52 contribute to the improved mechanical properties as illustrated in Table I.
  • martensitic grains of the control specimen of Table I are generally larger in size and may contribute to the lower ultimate tensile strength and 0.2% yield strength.
  • the disclosed method 20 provides a desirable combination of forming and heat treating the workpiece of maraging steel 22 to obtain improved properties, and an economic process that eliminates the need for a heat treatment step between the thermomechanical processing step 24 and the direct aging step 26.
  • the present invention also extends to a component produced according to a preferred method of the present invention.

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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 Steel (AREA)
EP09251975A 2008-08-14 2009-08-11 Procédé de traitement d'acier maraging Ceased EP2157196A1 (fr)

Applications Claiming Priority (1)

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US12/191,375 US20100037994A1 (en) 2008-08-14 2008-08-14 Method of processing maraging steel

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EP2157196A1 true EP2157196A1 (fr) 2010-02-24

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EP09251975A Ceased EP2157196A1 (fr) 2008-08-14 2009-08-11 Procédé de traitement d'acier maraging

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EP (1) EP2157196A1 (fr)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103063549A (zh) * 2012-12-26 2013-04-24 广东电网公司电力科学研究院 T/p91钢基于析出相颗粒直径大小的老化评级方法
DE102016102770A1 (de) * 2016-02-17 2017-08-17 Dr. Ing. H.C. F. Porsche Aktiengesellschaft Verfahren zur Herstellung eines Bauteils, insbesondere eines Fahrwerksbauteils, eines Kraftfahrzeugs
WO2020128568A1 (fr) 2018-12-17 2020-06-25 Arcelormittal Acier laminé à chaud et son procédé de fabrication
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
US3093519A (en) * 1961-01-03 1963-06-11 Int Nickel Co Age-hardenable, martensitic iron-base alloys
US3359094A (en) * 1965-05-20 1967-12-19 Int Nickel Co Ferrous alloys of exceptionally high strength
US3453102A (en) * 1966-03-08 1969-07-01 Int Nickel Co High strength,ductile maraging steel
JPH08218122A (ja) * 1995-02-13 1996-08-27 Daido Steel Co Ltd マルテンサイト系析出強化型ステンレス鋼の高強度ボルト及びねじの製造方法
JP2005163126A (ja) * 2003-12-03 2005-06-23 Daido Steel Co Ltd 時効硬化型ステンレス鋼またはマルエージング鋼の部品とその製造方法

Family Cites Families (7)

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Publication number Priority date Publication date Assignee Title
US4098607A (en) * 1976-11-04 1978-07-04 The United States Of America As Represented By The Secretary Of The Army 18% Ni-Mo-Co maraging steel having improved toughness and its method of manufacture
JPS59170244A (ja) * 1983-03-16 1984-09-26 Mitsubishi Heavy Ind Ltd 強靭無Ｃｏマルエ−ジング鋼
US4579602A (en) * 1983-12-27 1986-04-01 United Technologies Corporation Forging process for superalloys
US5435828A (en) * 1993-12-21 1995-07-25 United Technologies Corporation Cobalt-boride dispersion-strengthened copper
US5451142A (en) * 1994-03-29 1995-09-19 United Technologies Corporation Turbine engine blade having a zone of fine grains of a high strength composition at the blade root surface
DE10010383B4 (de) * 1999-03-04 2004-09-16 Honda Giken Kogyo K.K. Verfahren zur Herstellung von Maraging-Stahl
DE502005005216D1 (de) * 2004-10-29 2008-10-09 Alstom Technology Ltd Kriechfester martensitisch-härtbarer vergütungsstahl

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3093519A (en) * 1961-01-03 1963-06-11 Int Nickel Co Age-hardenable, martensitic iron-base alloys
US3359094A (en) * 1965-05-20 1967-12-19 Int Nickel Co Ferrous alloys of exceptionally high strength
US3453102A (en) * 1966-03-08 1969-07-01 Int Nickel Co High strength,ductile maraging steel
JPH08218122A (ja) * 1995-02-13 1996-08-27 Daido Steel Co Ltd マルテンサイト系析出強化型ステンレス鋼の高強度ボルト及びねじの製造方法
JP2005163126A (ja) * 2003-12-03 2005-06-23 Daido Steel Co Ltd 時効硬化型ステンレス鋼またはマルエージング鋼の部品とその製造方法

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
BUSH, R.H.: "Mechanical properties of ausformed maraging steel", ASM TRANSACTIONS QUARTERLY, vol. 56, no. 4, December 1963 (1963-12-01), US, pages 885 - 887, XP009125862 *
DATABASE COMPENDEX [online] ENGINEERING INFORMATION, INC., NEW YORK, NY, US; BUSH R H: "Mechanical properties of ausformed maraging steel", XP002555761, Database accession no. EIX19640039813 *
HE Y ET AL: "Strengthening and toughening of a 2800-MPa grade maraging steel", MATERIALS LETTERS, NORTH HOLLAND PUBLISHING COMPANY. AMSTERDAM, NL, vol. 56, no. 5, 1 November 2002 (2002-11-01), pages 763 - 769, XP004388931, ISSN: 0167-577X *

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