EP2154263A1 - Gehäusehärtendes Titanium und seine Legierungen - Google Patents

Gehäusehärtendes Titanium und seine Legierungen Download PDF

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Publication number
EP2154263A1
EP2154263A1 EP09251856A EP09251856A EP2154263A1 EP 2154263 A1 EP2154263 A1 EP 2154263A1 EP 09251856 A EP09251856 A EP 09251856A EP 09251856 A EP09251856 A EP 09251856A EP 2154263 A1 EP2154263 A1 EP 2154263A1
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EP
European Patent Office
Prior art keywords
titanium
article
range
carbon monoxide
per million
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Withdrawn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
EP09251856A
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English (en)
French (fr)
Inventor
Paul Stratton
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BOC Group Ltd
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BOC Group Ltd
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Filing date
Publication date
Application filed by BOC Group Ltd filed Critical BOC Group Ltd
Publication of EP2154263A1 publication Critical patent/EP2154263A1/de
Withdrawn legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
    • C23C8/10—Oxidising
    • C23C8/16—Oxidising using oxygen-containing compounds, e.g. water, carbon dioxide
    • 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
    • C21D1/74—Methods of treatment in inert gas, controlled atmosphere, vacuum or pulverulent material
    • C21D1/76—Adjusting the composition of the atmosphere
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
    • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
    • C22F1/16—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of other metals or alloys based thereon
    • C22F1/18—High-melting or refractory metals or alloys based thereon
    • C22F1/183—High-melting or refractory metals or alloys based thereon of titanium or alloys based thereon

Definitions

  • This invention relates to a thermal treatment method.
  • it relates to a method of case hardening an article of titanium or of an alloy based on titanium.
  • Titanium has poor tribological properties.
  • Various coatings can used, for example titanium nitride, to improve the technological properties of the metal and its alloys but even so, their use in engineering is limited by the low strength of the substrate. Accordingly thermochemical diffusion treatments have been developed. To produce to a layer that is sufficiently thick to support a load in a reasonable time, oxidising and nitriding treatments are preferred at 965°C and 1050°C respectively. These high treatment temperatures degrade the core properties of the metal or alloy to such an extent that a further heat treatment becomes necessary after the formation of the case.
  • WO-A-96/23908 discloses a process for manufacturing a titanium article with a hardened surface for enhanced wear resistance comprising the steps of exposing the article to an oxygen-containing environment; heating the article to a temperature that allows oxygen to diffuse into the article; soaking the article at the temperature for a time sufficient to oxidise elemental metal at the surface and cooling the article to room temperature. The heating and soaking take place at about 500°C, and the oxygen-containing environment is an atmosphere of air.
  • US-A-5 316 594 relates to forming a hardened outer shell on a refractory titanium workpiece using an argon-oxygen atmosphere containing from 1 to 3 mole percent of oxygen at a maximum treatment temperature of 815°C.
  • EP-A-580 081 relates to the treatment of intermetallic compounds of titanium and aluminium in an atmosphere containing 20% by volume of oxygen.
  • US-A-4 263 060 relates to the treatment of titanium articles with oxygen at a subatmospheric pressure.
  • WO-A-99/04055 (The University of Birmingham) discusses the need to provide engineering alloys of titanium or zirconium with a hard case consisting of a region of relatively high hardness maintained to a certain depth below the surface before dropping more steeply and then gradually to the hardness of the untreated core material.
  • WO-A-99104055 discloses a method of case hardening an article formed of titanium, zirconium or an alloy of titanium and/or zirconium in which the article is heat treated for a short period of time, typically from 0.3 to 0.6 hour, in an oxidising atmosphere containing both oxygen and nitrogen (typically air) at a temperature in the range of 700 to 1000°C so as to form an oxide layer on the article, and then further heat treating the article in a vacuum or in a neutral or an inert atmosphere at a temperature in the range of 700 to 1000°C so as to cause oxygen from the oxide layer to diffuse into the article.
  • an oxidising atmosphere typically air
  • nitrogen typically air
  • the case hardened article may then be surface treated by the method according to WO-A-98/02595 (The University of Birmingham) so as to improve the tribological behaviour of the article.
  • This surface treatment comprises gaseous oxidation of the article at a temperature in the range of 500 to 725°C for 0.1 to 100 hours, the temperature and time being selected such as to produce an adherent surface component layer containing at least 50% by weight of oxides of titanium having a rutile structure and a thickness of 0.2 to 2 ⁇ m on a solid solution-strengthened diffusion zone wherein the diffusing element is oxygen and the diffusion zone has a depth of 5 to 50 ⁇ m.
  • the dual step oxidation/diffusion treatment of the method according to WO-A-99/04055 is difficult to control.
  • a small variation in the amount of oxide formed in the first oxidation step can result in a significant difference in the eventual hardness profile at the end of the diffusion time in the vacuum or the neutral or inert atmosphere.
  • the method therefore relies entirely on empirical control, thereby causing difficulties if it is required to treat a range of articles of different shapes and sizes.
  • a method of case hardening an article of titanium or a titanium-based alloy, or of zirconium or a zirconium-based alloy, wherein the article is heat treated at one or more temperatures in the range of 850°C to 900°C and at a pressure in the order of atmospheric pressure in an oxygen diffusion atmosphere comprising (a) a carrier gas which does not react chemically with the article in the said temperature range and (b) molecular oxygen, wherein the concentration of oxygen in the oxygen diffusion atmosphere is in the range of 10 volumes per million to 400 volumes per million.
  • the method according to WO-A-2004/007788 is an improvement over prior methods because it enables a hard case to be formed in a single treatment step at atmospheric pressure and is easy to control.
  • a balance has to be struck between the temperature at which the work is subjected to the oxygen diffusion atmosphere and the duration of the treatment.
  • temperatures in the order of 900°C favour shorter treatment times than temperatures in the order of 800°C.
  • temperatures in the order of 900 °C some undesirable microstructural coarsening of the grains within the work takes place. It is thus undesirable to exceed a temperature much above 850 °C.
  • 850 °C we have found that total duration of the period of time throughout which the work needs to be exposed to the oxygen diffusion for a case of adequate thickness of some industrial uses can be unacceptably long and typically over 24 hours.
  • a method of case hardening an article of a metallic material selected from titanium and titanium - based alloys wherein the article is heat treated at a pressure in the range of 0.5 to 2 bar and a temperature in the range of 750 to 870 °C in a diffusion atmosphere comprising (a) carrier gas which does not react chemically with the article in the said temperature range and (b) as active gas, wherein the concentration of the active gas in the diffusion atmosphere is in the range of 20 to 400 volumes per million, and wherein the active gas is carbon monoxide.
  • the carbon monoxide concentration in the diffusion atmosphere is preferably in the range of 30 to 100 volumes per million. Reducing the carbon monoxide concentration below 30 parts per million can increase the time it takes to form a hard case of given depth. Increasing the concentration of carbon monoxide above 100 volumes per million does not appear to increase significantly the rate of formation or the ultimate depth of the case but it does have the effect of increasing the depth of a ceramic layer formed on the surface of the work by virtue of the active gas. Concentrations of carbon monoxide above 400 parts per million can result in the formation of an impermeable surface layer that prevents the achievement of an adequate case depth.
  • a further advantage of the method according to the present invention is that a wear-resistant ceramic layer can be formed at the surface of the work.
  • titanium-based alloy as used herein has its usual meaning. That is an alloy containing more than 50% by weight of titanium. Typical alloying elements for use in titanium-based alloys include vanadium and aluminium.
  • the carrier gas is preferably a noble gas such as helium, xenon, neon or argon, or a mixture of one or more such noble gases.
  • Argon is particularly preferred.
  • Other gases may be included if they do not have any marked adverse affect on the required metallurgical engineering properties of the article. For example, traces of nitrogen at the parts per million level are typically found in commercially available argon and can be tolerated in the method according to the invention.
  • the method according to the invention is preferably performed at a pressure that is essentially the same as the prevailing atmospheric pressure, i.e. at a pressure in the range of 0.9 to 1.2 bar.
  • the duration of the heat treatment is preferably in the range of 12 to 24 hours.
  • the method according to the present invention is particularly useful in case hardening engineering components or other articles formed of commercially pure grades of titanium, of titanium-based alloys ( ⁇ , ⁇ + ⁇ , or ⁇ alloys).
  • the article When the article is required to have enhanced fatigue properties, it may be subjected after heat treatment to a mechanical surface treatment, such as shot peening.
  • samples were treated in a small Boye pit furnace that had previously been used for carburising treatments. It was therefore thoroughly burnt out first, together with its loading jig, to ensure that no residues - particularly carbon - were present that might affect the results. This was done by passing carbon dioxide-free air through the furnace at 850°C for some hours while the carbon dioxide was monitored. Burnout was considered complete when the monitored carbon dioxide concentration began to fall.
  • the samples of the titanium-based alloy were in the form of polished cubes, 10mm per side. They were placed in the pit furnace at ambient temperature. The furnace was then heated under a flow or argon. When the processing temperature was reached, the processing gas mixture was introduced. At the end of the processing time the atmosphere was replaced by argon and the furnace cooled to below 150 °C before the samples were removed.
  • the active gas level as measured in the outlet stream, varied slightly during a given treatment so all the results below are experienced with reference to the average level over the treatment period.
  • Samples were treated for 24 hours using a carbon monoxide concentration of 50 volumes per million and temperatures of 750°C, 800°C and 850°C in accordance with the invention, and 900 °C by way of comparison.
  • Case depth is shown graphically in Figure 2 . Case depth is shown to increase with temperature. The results obtained were corrected for the small differences from the nominal 50 volumes per million carbon monoxide level in the measured carbon monoxide concentrations.
  • Another effect of the treatment is to tend to cause structural coarsening. Such coarsening was not significant for the treatment temperatures of 750 °C, 800 °C and 850 °C but was manifest in the samples treated at 900 °C. As a result the samples treated at 900 °C would have been unsuitable for many engineering uses because the structural coarsening inevitably lowers core strength. This would be particularly a problem for larger engineering components that require a deeper case than in the samples produced in accordance with this example.
  • Test specimens of the T. - 6AL - 4V alloy were produced by heat treatment for 24 hours at 850 °C and atmospheric pressure in first a gas mixture of 50 parts by volume (volumes) per million of oxygen in argon, secondly 80 parts by volume (volumes) of carbon monoxide in argon, and thirdly 25 parts by volume carbon dioxide in argon. The concentrations were chosen to ensure that a thin ceramic surface layer was formed on each test specimen.
  • the treated specimens were subjected to dry wear tests on a pin-disc machine employing a stationary vertical bar and a rotary disc.
  • the heat treated specimen is attached to the vertical bar and the disc rotated.
  • the disc was made from a cold working tool steel hardened and tempered to 58RC.
  • the disc brings a high pressure (approximately 4N/mm 2 to bear on the sample.
  • Resultant marks on the sample were then analysed by methods well known in the art.
  • the hardness of each specimen was also measured. The results obtained are shown graphically in Figures 3 and 4.
  • Figure 3 shows that the carbon monoxide - treated samples had a significantly harder case than either the carbon dioxide - treated sample or the oxygen - treated sample.
  • Figure 4 shows that the wear rate of the carbon monoxide-treated specimen is half that of the oxygen-treated specimen with the carbon dioxide treated specimen lying between them.

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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)
  • Chemical Kinetics & Catalysis (AREA)
  • Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
EP09251856A 2008-07-25 2009-07-23 Gehäusehärtendes Titanium und seine Legierungen Withdrawn EP2154263A1 (de)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GBGB0813667.3A GB0813667D0 (en) 2008-07-25 2008-07-25 Case hardening titanium and its alloys

Publications (1)

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EP2154263A1 true EP2154263A1 (de) 2010-02-17

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CA (1) CA2673897A1 (de)
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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102703852A (zh) * 2012-06-15 2012-10-03 西北有色金属研究院 一种两相钛合金表面复合无氢氧碳共渗的方法
CN104032272A (zh) * 2014-06-05 2014-09-10 淮阴工学院 在医用镁合金表面制备非晶氧化钛活性膜层的方法
US11060175B2 (en) 2016-06-02 2021-07-13 Danmarks Tekniske Universitet Case hardened component of titanium

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109706421B (zh) * 2019-03-07 2020-08-18 苏州微创关节医疗科技有限公司 制备锆及锆合金表面氧化陶瓷层的方法及应用
CN118703929B (zh) * 2024-06-03 2026-02-17 广东省科学院新材料研究所 一种金属表面陶瓷化层及其制备方法和应用

Citations (12)

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Publication number Priority date Publication date Assignee Title
JPS5051039A (de) * 1973-09-05 1975-05-07
US4263060A (en) 1973-11-09 1981-04-21 Centre Stephanois De Recherches Mecanique Hydromecanique Et Frottement Method for treating parts made of titanium or titanium alloy, and parts produced thereby
GB2118978A (en) * 1982-04-23 1983-11-09 Maschf Augsburg Nuernberg Ag Forming oxide layer on titanium
JPH059703A (ja) * 1991-06-28 1993-01-19 Nkk Corp チタン材の表面硬化処理方法
EP0580081A1 (de) 1992-07-17 1994-01-26 Sumitomo Light Metal Industries Limited Erzeugnis aus einer intermetallischen Verbindung des Ti-Al-Systems mit hoher Widerstandsfähigkeit gegen Oxidation und Verschleiss und Verfahren zur Herstellung dieses Erzeugnisses
US5316594A (en) 1990-01-18 1994-05-31 Fike Corporation Process for surface hardening of refractory metal workpieces
WO1996023908A1 (en) 1995-01-31 1996-08-08 Smith & Nephew Richards Inc. Wear resistant tribosystem
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WO1998002595A1 (en) 1996-07-17 1998-01-22 The University Of Birmingham Surface oxidation of a titanium or titanium alloy article
WO1999004055A1 (en) 1997-07-19 1999-01-28 The University Of Birmingham Method of case hardening
WO2004007788A1 (en) 2002-07-16 2004-01-22 The Boc Group Plc Method of case hardening titanium and zirconium alloys
US20050234561A1 (en) * 2004-04-20 2005-10-20 Michael Nutt Surface treatment for implants

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* Cited by examiner, † Cited by third party
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JPS5051039A (de) * 1973-09-05 1975-05-07
US4263060A (en) 1973-11-09 1981-04-21 Centre Stephanois De Recherches Mecanique Hydromecanique Et Frottement Method for treating parts made of titanium or titanium alloy, and parts produced thereby
GB2118978A (en) * 1982-04-23 1983-11-09 Maschf Augsburg Nuernberg Ag Forming oxide layer on titanium
US5316594A (en) 1990-01-18 1994-05-31 Fike Corporation Process for surface hardening of refractory metal workpieces
JPH059703A (ja) * 1991-06-28 1993-01-19 Nkk Corp チタン材の表面硬化処理方法
EP0580081A1 (de) 1992-07-17 1994-01-26 Sumitomo Light Metal Industries Limited Erzeugnis aus einer intermetallischen Verbindung des Ti-Al-Systems mit hoher Widerstandsfähigkeit gegen Oxidation und Verschleiss und Verfahren zur Herstellung dieses Erzeugnisses
WO1996023908A1 (en) 1995-01-31 1996-08-08 Smith & Nephew Richards Inc. Wear resistant tribosystem
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WO1998002595A1 (en) 1996-07-17 1998-01-22 The University Of Birmingham Surface oxidation of a titanium or titanium alloy article
WO1999004055A1 (en) 1997-07-19 1999-01-28 The University Of Birmingham Method of case hardening
WO2004007788A1 (en) 2002-07-16 2004-01-22 The Boc Group Plc Method of case hardening titanium and zirconium alloys
US20050234561A1 (en) * 2004-04-20 2005-10-20 Michael Nutt Surface treatment for implants

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Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102703852A (zh) * 2012-06-15 2012-10-03 西北有色金属研究院 一种两相钛合金表面复合无氢氧碳共渗的方法
CN104032272A (zh) * 2014-06-05 2014-09-10 淮阴工学院 在医用镁合金表面制备非晶氧化钛活性膜层的方法
CN104032272B (zh) * 2014-06-05 2016-08-17 淮阴工学院 在医用镁合金表面制备非晶氧化钛活性膜层的方法
US11060175B2 (en) 2016-06-02 2021-07-13 Danmarks Tekniske Universitet Case hardened component of titanium
EP3878999A1 (de) 2016-06-02 2021-09-15 Danmarks Tekniske Universitet Verfahren zur oxidation von titan

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US20100139812A1 (en) 2010-06-10
GB0813667D0 (en) 2008-09-03
CA2673897A1 (en) 2010-01-25

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