EP1871917A1 - Boron steel grade for induction hardening and shaft - Google Patents

Boron steel grade for induction hardening and shaft

Info

Publication number
EP1871917A1
EP1871917A1 EP06717138A EP06717138A EP1871917A1 EP 1871917 A1 EP1871917 A1 EP 1871917A1 EP 06717138 A EP06717138 A EP 06717138A EP 06717138 A EP06717138 A EP 06717138A EP 1871917 A1 EP1871917 A1 EP 1871917A1
Authority
EP
European Patent Office
Prior art keywords
induction hardening
molybdenum
nickel
boron steel
boron
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Withdrawn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
EP06717138A
Other languages
German (de)
English (en)
French (fr)
Inventor
Erik Sandqvist
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.)
Scania CV AB
Original Assignee
Scania CV AB
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 Scania CV AB filed Critical Scania CV AB
Publication of EP1871917A1 publication Critical patent/EP1871917A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/02Ferrous alloys, e.g. steel alloys containing silicon
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/18Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/40Ferrous alloys, e.g. steel alloys containing chromium with nickel
    • C22C38/54Ferrous alloys, e.g. steel alloys containing chromium with nickel with boron
    • CCHEMISTRY; METALLURGY
    • C22METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22CALLOYS
    • C22C38/00Ferrous alloys, e.g. steel alloys
    • C22C38/04Ferrous alloys, e.g. steel alloys containing manganese

Definitions

  • the present invention relates to a boron steel grade according to the introductory part of the attached claim 1.
  • the invention also relates to a shaft made of boron steel according to the introductory part of the attached claim 6.
  • Low-alloy boron steel is used inter alia for shafts which by induction hardening of a surface zone are provided with increased fatigue and static strength but also a wear-resistant surface layer.
  • Induction hardening of this kind causes in the surface zone compressive stresses which counteract the occurrence of fatigue cracks in this surface zone and thereby have a positive effect on fatigue strength.
  • the relationship between the magnitude of the compressive stresses and the fatigue strength is unambiguous. The greater the compressive stresses, the higher the fatigue strength.
  • the compressive stresses in the surface zone are balanced by tensile stresses in central portions (the core).
  • Tensile stresses in the core do not normally affect strength, since the level of stresses arising from imposed loads is low in specifically the core.
  • stationary induction hardening also called single-shot hardening, i.e. a hardening operation where the total volume to be hardened is first heated to the hardening temperature and is thereafter cooled immediately or after a certain delay
  • the compressive stresses in the surface zone become particularly high and the fatigue strength becomes better than is achieved by progressive induction hardening where heating and subsequent cooling are effected during continuous mutual movement between inductor/cooling shower and the workpiece which is to be hardened.
  • the stresses, not least the tensile stresses in the core in the case of stationary induction hardening may become so great during the actual hardening process that cracks (central cracks) occur in the core.
  • a typical and representative ratio is about 20,000 load cycles at 20 kNm torsional fatigue for progressive induction hardening as against about 80,000 load cycles at 20 kNm torsional fatigue for stationary induction hardening.
  • the object of the present invention is to provide low-alloy boron steel which can be induction-hardened statically without central cracks occurring.
  • Fig. 1 depicts a compilation in tabular form concerning Hie incidence of cracks as a function of composition, where primarily the molybdenum and nickel contents clearly vary
  • Fig. 2 depicts in diagram form the incidence of cracks as a function of molybdenum and nickel contents
  • FIG. 3 depicts in an axial section a driveshaft for which experiments with steel grades according to the present invention were carried out.
  • the steel grades according to the invention are low-allow boron steel, and steel grades according to the invention with the range of composition according to the invention appear in Table 1 together with a corresponding known steel grade.
  • Carbon which has a substantial influence on induction hardening characteristics, is present in contents of between 0.30 and 0.50%, resulting in desired strength after hardening. A carbon content amounting to 0.38-0.45% is preferred.
  • Silicon is present in an amount of 0.15-0.40%, preferably more than 0.15% up to 0.40%, and is primarily added as a carrier for other alloying elements, but also has some strengthening effect.
  • Manganese is present in an amount of 1.10 up to 1.50%, preferably more than 1.10% up to 1.50%, and has strengthening effects partly by increasing the hardenability, which, where there is great hardness depth, may affect the hardness depth in induction hardening. Manganese is also added in order to bind sulphur which would otherwise have adverse effects on impact strength.
  • the phosphorus content, ⁇ 0.035%, has to be kept low to prevent brittleness and hardness cracks due to grain boundary weakening.
  • MnS manganese sulphide
  • Chrome is present in an amount ⁇ 0.5%, preferably more than 0.2% and less than 0.5%. Chrome increases hardenability and reduces the risk of decarburisation.
  • Molybdenum in an amount of 0.030% and up to 0.15% has according to the invention proved to be able, together with certain contents of nickel as below, to prevent the occurrence of central cracks, inter alia in static induction hardening.
  • the molybdenum content is normally not even specified for boron steel of this kind. It is also likely that such an addition of molybdenum in combination with nickel also reduces the risk of hardness cracks in other grades.
  • Molybdenum in a quantity of 0.05 up to 0.15% is preferred.
  • Nickel in an amount of 0.15% up to 0.40% has proved, together with molybdenum as above, according to the invention, to be able to prevent the occurrence of central cracks, inter alia in static induction hardening.
  • the nickel content is likewise not usually specified.
  • Nickel is regarded as an impurity. It is also likely that such an addition of molybdenum in combination with nickel also reduces the risk of hardness cracks in other grades.
  • Nickel in an amount of more than 0.20 up to 0.40% is preferred.
  • Titanium in certain contents is needed for keeping a certain content of boron in solid solution in the steel with a view to improving the hardening characteristics. Titanium should therefore be present in an amount of 0.020-0.050%. Aluminium is a deoxidant and is therefore present in low contents. Aluminium impairs the fatigue strength by forming aluminium oxide, and aluminium contents should be kept ⁇ 0.050%.
  • the desirable content in solid solution is at least 0.0005%, while the total content should be limited to less than 0.004%.
  • molybdenum and nickel constitute impurities which are not even specified in a standard composition.
  • the composition ranges for molybdenum and nickel which result in the crack-eliminating effect according to the invention nevertheless comprise contents which clearly exceed prevailing impurity levels.
  • Fig. 1 shows the incidence of cracks on a large number of driveshafts from a large number of charges with mutual varying chemical composition
  • "No.” denotes the number of shafts in which cracks were detected
  • “Tot.” the total number of shafts examined for each steel charge
  • “Incid. %” the ratio between "No.” and “Tot”, i.e. the proportion of shafts with detected cracks.
  • Fig. 2 shows the incidence of cracks, "Crack Incidence %", as a function of molybdenum content and nickel content, although for manufacturing reasons the effect of molybdenum content or nickel content would be isolated.
  • the minimum contents indicated have been adjusted by a small margin to the respective content combinations of 0.035% molybdenum/0.167% nickel and 0.038 molybdenum/0.188% nickel, which resulted in no cracks.
  • the preferred minimum contents have been provided with a margin upwards relative to the minimum contents extracted.
  • An upper content limit has also been set for both molybdenum and nickel. This is partly for cost reasons and for preventing disadvantages, e.g. impaired machinability, which occur at increasing molybdenum and nickel contents.
  • Scania boron steel TB 1639 as a low-alloy material is specified in Table 1 below.
  • Low-alloy compositions are usually stated without contents of molybdenum and nickel, which substances are to be regarded as common impurities.
  • a general composition according to the invention, a preferred composition and a detailed composition which in experiments resulted in lack of cracks are also specified.
  • Table 1 Composition of boron steel according to the state of the art and the invention.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Articles (AREA)
  • Shafts, Cranks, Connecting Bars, And Related Bearings (AREA)
EP06717138A 2005-04-12 2006-04-06 Boron steel grade for induction hardening and shaft Withdrawn EP1871917A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0500812A SE527221C2 (sv) 2005-04-12 2005-04-12 Borstålsort för induktionshärdning jämte axel
PCT/SE2006/050059 WO2006110100A1 (en) 2005-04-12 2006-04-06 Boron steel grade for induction hardening and shaft

Publications (1)

Publication Number Publication Date
EP1871917A1 true EP1871917A1 (en) 2008-01-02

Family

ID=35653953

Family Applications (1)

Application Number Title Priority Date Filing Date
EP06717138A Withdrawn EP1871917A1 (en) 2005-04-12 2006-04-06 Boron steel grade for induction hardening and shaft

Country Status (6)

Country Link
EP (1) EP1871917A1 (sv)
JP (1) JP2008537982A (sv)
CN (1) CN101155941B (sv)
BR (1) BRPI0608675A2 (sv)
SE (1) SE527221C2 (sv)
WO (1) WO2006110100A1 (sv)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101624675B (zh) * 2009-07-30 2011-02-16 莱芜钢铁股份有限公司 履带链轨销轴用45bm钢及其制造方法

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2725747B2 (ja) * 1990-11-16 1998-03-11 大同特殊鋼株式会社 高周波焼入れ用鋼材
JP2916069B2 (ja) * 1993-09-17 1999-07-05 新日本製鐵株式会社 高強度高周波焼入れ軸部品
JP3432944B2 (ja) * 1995-03-16 2003-08-04 新日本製鐵株式会社 捩り疲労強度の優れた高周波焼入れ軸部品用鋼材
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
JPH10195589A (ja) * 1996-12-26 1998-07-28 Nippon Steel Corp 高捩り疲労強度高周波焼入れ鋼材
JPH11181542A (ja) * 1997-12-16 1999-07-06 Nippon Steel Corp 冷間加工性と高周波焼入れ性に優れた高周波焼入れ用鋼材とその製造方法
DE60222595T2 (de) * 2002-10-18 2008-06-19 Jfe Steel Corp. Stahlmaterial für mechanische konstruktionen mit hervorragender walzbarkeit, abschreckungsrissfestigkeit und torsionseigenschaft und antriebswelle
JP3774697B2 (ja) * 2002-12-04 2006-05-17 新日本製鐵株式会社 高強度高周波焼き入れ用鋼材及びその製造方法
JP2005048211A (ja) * 2003-07-30 2005-02-24 Jfe Steel Kk 疲労特性に優れた鋼材の製造方法

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2006110100A1 *

Also Published As

Publication number Publication date
JP2008537982A (ja) 2008-10-02
SE0500812L (sv) 2006-01-24
SE527221C2 (sv) 2006-01-24
CN101155941A (zh) 2008-04-02
CN101155941B (zh) 2010-09-08
WO2006110100A1 (en) 2006-10-19
BRPI0608675A2 (pt) 2010-01-19

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