US20040081576A1 - Titanium-added, high strength steel - Google Patents

Titanium-added, high strength steel Download PDF

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Publication number
US20040081576A1
US20040081576A1 US10/292,417 US29241702A US2004081576A1 US 20040081576 A1 US20040081576 A1 US 20040081576A1 US 29241702 A US29241702 A US 29241702A US 2004081576 A1 US2004081576 A1 US 2004081576A1
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United States
Prior art keywords
steel
titanium
added
ppm
tin
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Abandoned
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US10/292,417
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English (en)
Inventor
Kazuhiko Hiraoka
Shuhei Kitano
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Sanyo Special Steel Co Ltd
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Sanyo Special Steel Co Ltd
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Assigned to SANYO SPECIAL STEEL CO., LTD. reassignment SANYO SPECIAL STEEL CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: HIRAOKA, KAZUHIKO, KITANO, SHUHEI
Publication of US20040081576A1 publication Critical patent/US20040081576A1/en
Abandoned legal-status Critical Current

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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
    • C22C38/02—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
    • C22C38/001—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
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • 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
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • 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
    • 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
    • C22C38/44—Ferrous alloys, e.g. steel alloys containing chromium with nickel with molybdenum or tungsten
    • 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

Definitions

  • the present invention relates to a titanium(Ti)-added, high strength steel as a steel for machine construction for use in automobile components and components of other various industrial machines or apparatuses.
  • Steels for machine construction for example, SC steel, SMn steel, SCr steel, SCM steel, SNC steel, SNCM steel, and SUJ steel specified in JIS (Japanese Industrial Standards) and the above steels with boron and/or minor elements being further added thereto have hitherto been used in automobile components and components of other various industrial machines or apparatuses.
  • steels, in which titanium in an amount of not less than 500 ppm has been added as a steel constituent are known (see, for example, Japanese Patent Laid-Open Nos. 283910/1996, 130720/1998, 251806/1998, 293403/1999, and 293392/1999).
  • a titanium-added, high strength steel as a steel for machine construction comprising, by weight, titanium: not less than 500 ppm as a steel constituent, the content of nitrogen (N) being N ⁇ 100 ppm.
  • a titanium-added, high strength steel as a steel for machine construction comprising, by weight, titanium: not less than 500 ppm, the maximum size of TiN and/or TiCN crystallized in the steel, ⁇ square root ⁇ square root over (area max) ⁇ , being not more than 80 ⁇ m as predicted in a measurement area of 30000 mm 2 by an extreme value statistical method.
  • a titanium-added, high strength steel as a steel for machine construction comprising, by weight, titanium: not less than 500 ppm, the content of nitrogen (N) being N ⁇ 100 ppm, the maximum size of TiN and/or TiCN crystallized in the steel, ⁇ square root ⁇ square root over (area max) ⁇ , being not more than 80 ⁇ m as predicted in a measurement area of 30000 mm 2 by an extreme value statistical method.
  • ⁇ square root ⁇ square root over (area max) ⁇ is the square root of the area of the maximum inclusion non-metallic inclusion present in a measurement area predicted by an extreme value statistical method, and, in the present invention, refers to the maximum size of TiN and/or TiCN which has been crystallized in the steel.
  • the steel as the basis in the means of the present invention is a steel for machine construction
  • the object steel of the present invention is a steel for machine construction such that titanium has been added to the base steel for machine construction and the nitrogen content has been regulated.
  • the steel for machine construction as the base steel in the present invention is preferably based on a steel selected from the group consisting of SC steel (JIS G 4051 (1979)), SMn steel (JIS G 4106 (1979)), SCr steel (JIS G 4104 (1979)), SCM steel (JIS G 4105 (1979)), SNC steel (JIS G 4102 (1979)), SNCM steel (JIS G 4103 (1979)), and SUJ steel (JIS G 4805 (1999) ) and further comprises titanium and nitrogen and optionally minor elements with the balance comprising unavoidable impurities and satisfies the above requirements for titanium, nitrogen, and, in addition, TiC and TiCN.
  • SC steel JIS G 4051 (1979)
  • SMn steel JIS G 4106 (1979)
  • SCr steel JIS G 4104 (1979)
  • SCM steel JIS G 4105 (1979)
  • SNC steel JIS G 4102 (1979)
  • SNCM steel JIS G 4103 (1979)
  • minor elements refers to elements which, when contained in an amount of not more than about 0.5%, offer an effect beneficial to the steel. Further, the term “optionally” means that the minor elements may be contained according to need depending upon applications, or may not be contained at all. Representative examples of minor elements will be described.
  • Aluminum (Al) is an element which is frequently used as a deoxidizing element and may be contained in an amount up to 0.05%.
  • Boron (B) is an element which improves harden ability and may be contained in an amount up to 50 ppm.
  • Lead (Pb), bismuth (Bi), tellurium (Te), and selenium (Se) are elements which improve machinability and may be contained in an amount up to 0.3%.
  • calcium (Ca) may be contained in an amount up to 0.010%
  • sulfur (S) may be contained in an amount up to 0.3%.
  • the nitrogen content is N ⁇ 100 ppm by weight, preferably N ⁇ 80 ppm by weight.
  • the titanium-added steel possesses excellent properties by virtue of TiC or carbon(C)-rich TiCN which has been finely precipitated in a size of not more than 100 nm by the addition of titanium. Titanium, however, reacts with nitrogen and carbon and consequently causes the crystallization of non-metallic inclusions of TiN or nitrogen-rich TiCN (TiN and nitrogen-rich TiCN being hereinafter collectively referred to as “TiN”). The crystallized non-metallic inclusions adversely affect the properties of the steel.
  • the crystallization of TiN is suppressed to bring the added titanium to precipitated TiC or carbon-rich TiCN having a size of not more than 100 nm which has a useful effect on the properties of the steel.
  • the content of nitrogen contained in the steel is limited to N ⁇ 100 ppm by weight, preferably N ⁇ 80 ppm by weight.
  • the maximum size ( ⁇ square root ⁇ square root over (area max) ⁇ ) of TiN is regulated, and the maximum size ( ⁇ square root ⁇ square root over (area max) ⁇ ) of TiN is brought to not more than 80 ⁇ m, preferably not more than 60 ⁇ m.
  • the crystallized TiN serves as the origin of fatigue fracture. Whether or not the crystallized TiN serves as the origin of fatigue fracture is determined by the relationship of the size of the crystallized TiN and the size of oxide inclusions contained in the steel.
  • the maximum size of TiN exceeds 80 ⁇ m, there is a high possibility that this size is larger than the size of the oxide inclusions.
  • TiN serves as the origin of fatigue fracture, and, under service conditions such that inclusion-originated fatigue fracture occurs, the strength of the titanium-added steel is lower than the strength of the steel to which titanium has not been added.
  • the maximum size of TiN is brought to not more than 80 ⁇ m, the size of TiN is equal to or smaller than the size of the oxide inclusions and, in this case, the above lowering in strength does not occur.
  • FIG. 1 is a graph showing the relationship between the nitrogen content and the fatigue limit of steels of heat No. described in Example 1 for steels of the present invention as defined in claim 1 and steels for comparison with the steels of the present invention;
  • FIG. 2 is a graph showing the relationship between the fatigue limit and the maximum size of TiN, ⁇ square root ⁇ square root over (area max) ⁇ , in a rotary bending test of steels of heat described in Example 2 for steels of the present invention as defined in claims 2 and 3 and steels for comparison with the steels of the present invention;
  • FIG. 3 is a graph showing the relationship between the probability of TiN as the origin of fracture and the maximum size of TiN, ⁇ square root ⁇ square root over (area max) ⁇ , of steels of heat described in Example 2 for steels of the present invention as defined in claims 2 and 3 and steels for comparison with the steels of the present invention.
  • the metal structure of the corroded surface was observed, and the cooling rate was estimated from spacings of the dendrite arms. As a result, it was found that the cooling rate was about 1.1° C./min even at a portion around the center of the bloom which was solidified lastly.
  • the blooms were heated to a temperature of 1180° C. or above and were then hot rolled to billets of 150 mm ⁇ .
  • the billets were heated to a temperature of 1180° C. or above, and, after the rolling, the rolled steels are rapidly cooled to 1100° C. or below to prevent precipitates of TiC or carbon-rich TiCN from being grown to larger diameter grains.
  • the steel may be air cooled after the rolling. Otherwise, the rolled steel may be rapidly cooled, for example, by water cooling or air-blast cooling to suppress the growth of grains.
  • JIS Japanese Industrial Standards
  • SCr 420-based, SCM 420-based, SNCM 420-based, SNC 415-based, S45C-based, SMn 443-based, and SUJ 2-based titanium-added steels were produced by a melt process.
  • degassing time was varied so that the produced steels were different from one another in nitrogen content.
  • the resultant blooms were heated and stretched to 20 mm ⁇ , followed by normalizing.
  • the normalized products were machined to prepare test pieces for a rotary bending test.
  • the base steel is SCr 420, and nickel (Ni) and molybdenum (Mo) are unavoidable impurities.
  • the base steel is SCM 420, and nickel is an unavoidable impurity.
  • the base steel is SNCM 420.
  • the base steel is SNC 415, and molybdenum is an unavoidable impurity.
  • the base steel is S45C, and nickel, chromium (Cr), and molybdenum are unavoidable impurities.
  • the base steel is SMn 443, and nickel, chromium, and molybdenum are unavoidable impurities.
  • the base steel is SUJ 2, and nickel and molybdenum are unavoidable impurities.
  • the base steel is SUJ 2
  • boron is an additive element
  • nickel and molybdenum are unavoidable impurities.
  • titanium-added steels based on steels specified in JIS were produced by continuous casting.
  • solidification speed was controlled to vary the size of TiN to produce titanium-added steels with varied TiN size.
  • Samples were then prepared from the produced steel products.
  • the chemical compositions of the titanium-added steels are shown in Table 2.
  • the base steel and chemical composition thereof will be described.
  • the base steel is SCr 420, and nickel and molybdenum are unavoidable impurities.
  • heat B the base steel is SCM 420, and nickel is an unavoidable impurity.
  • the base steel is SNCM 420.
  • the base steel is SNC 415, and molybdenum is an unavoidable impurity.
  • the base steel is S45C, and nickel, chromium, and molybdenum are unavoidable impurities.
  • the base steel is SMn 443, and nickel, chromium, and molybdenum are unavoidable impurities.
  • the base steel is SUJ 2
  • nickel and molybdenum are unavoidable impurities.
  • the base steel is SUJ 2
  • boron is an additive element, and nickel and molybdenum are unavoidable impurities.
  • FIG. 2 represents data for medium carbon steel. It is apparent from FIG. 2 that, when ⁇ square root ⁇ square root over (area max) ⁇ exceeds 60 ⁇ m, the fatigue limit lowers; and, when ⁇ square root ⁇ square root over (area max) ⁇ exceeds 80 ⁇ m, the fatigue limit further lowers.
  • a high strength steel having improved fatigue strength for machine construction can be realized by a steel wherein titanium: not less than 500 ppm is contained as a steel constituent, and the nitrogen content is N ⁇ 100 ppm; a steel where in titanium: not less than 500 ppm is contained as a steel constituent, and the maximum size of TiN and/or TiCN crystallized in the steel, ⁇ square root ⁇ square root over (area max) ⁇ , is not more than 80 ⁇ m as predicted in a measurement area of 30000 mm 2 by an extreme value statistical method; and a steel simultaneously satisfying the requirements for both the above steels, that is, a steel wherein titanium: not less than 500 ppm is contained as a steel constituent, the nitrogen content is N ⁇ 100 ppm, and the maximum size of TiN and/or TiCN crystallized in the steel, ⁇ square root ⁇ square root over (area max) ⁇ , is not more than 80 ⁇ m as predicted in a measurement area of 30000

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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)
  • Treatment Of Steel In Its Molten State (AREA)
US10/292,417 2002-10-25 2002-11-12 Titanium-added, high strength steel Abandoned US20040081576A1 (en)

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JP2002311178A JP2004143550A (ja) 2002-10-25 2002-10-25 Ｔｉ添加高強度鋼
JP2002-311178 2002-10-25

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3128193B1 (en) * 2014-03-20 2022-10-26 NTN Corporation Bearing ring and roller bearing having said bearing ring

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102383052B (zh) * 2011-10-13 2013-07-10 浪莎针织有限公司 一种高耐磨性织针用钢的制造方法
CN103627979A (zh) * 2013-11-12 2014-03-12 铜陵市肆得科技有限责任公司 一种大型泵轴承钢材料及其制备方法
CN110773219B (zh) * 2019-10-30 2022-01-11 中国海洋大学 一种光-Fenton脱硫脱硝催化剂及其制备方法

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4472208A (en) * 1982-06-28 1984-09-18 Sumitomo Metal Industries, Ltd. Hot-rolled high tensile titanium steel plates and production thereof

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JP3432950B2 (ja) * 1995-04-17 2003-08-04 新日本製鐵株式会社 冷間加工性と捩り疲労強度特性を兼備した高周波焼入れ軸部品用鋼材
JPH10130720A (ja) * 1996-10-23 1998-05-19 Sanyo Special Steel Co Ltd 結晶粒度特性に優れた肌焼きボロン鋼の製造方法
JPH10251806A (ja) * 1997-03-14 1998-09-22 Sanyo Special Steel Co Ltd 転動疲労寿命に優れた鋼
JP4505064B2 (ja) * 1998-02-16 2010-07-14 三井化学株式会社 地盤固結改良剤
JP3426496B2 (ja) * 1998-04-09 2003-07-14 山陽特殊製鋼株式会社 耐遅れ破壊特性に優れた高強度長寿命浸炭用鋼及びその製造方法
DE19928775C2 (de) * 1998-06-29 2001-10-31 Nsk Ltd Induktionsgehärtete Wälzlagervorrichtung
JP2001020030A (ja) * 1999-07-02 2001-01-23 Kobe Steel Ltd 伸びフランジ性に優れた高強度熱延鋼板
JP3565428B2 (ja) * 2000-10-02 2004-09-15 株式会社住友金属小倉 機械構造用鋼材
JP3753101B2 (ja) * 2002-07-03 2006-03-08 住友金属工業株式会社 高強度高剛性鋼及びその製造方法
JP4168721B2 (ja) * 2002-10-10 2008-10-22 住友金属工業株式会社 高強度鋼材及びその製造方法

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4472208A (en) * 1982-06-28 1984-09-18 Sumitomo Metal Industries, Ltd. Hot-rolled high tensile titanium steel plates and production thereof

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3128193B1 (en) * 2014-03-20 2022-10-26 NTN Corporation Bearing ring and roller bearing having said bearing ring

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CN1293221C (zh) 2007-01-03
CN1498980A (zh) 2004-05-26
JP2004143550A (ja) 2004-05-20

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