EP1639143A2 - Process for improving the corrosion resistance of metals - Google Patents

Process for improving the corrosion resistance of metals

Info

Publication number
EP1639143A2
EP1639143A2 EP04734559A EP04734559A EP1639143A2 EP 1639143 A2 EP1639143 A2 EP 1639143A2 EP 04734559 A EP04734559 A EP 04734559A EP 04734559 A EP04734559 A EP 04734559A EP 1639143 A2 EP1639143 A2 EP 1639143A2
Authority
EP
European Patent Office
Prior art keywords
metal
process according
corrosion resistance
cryogenic treatment
piping
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Withdrawn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
EP04734559A
Other languages
German (de)
French (fr)
Inventor
Timothy Craig Garrison
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.)
Avecia Inc
Original Assignee
Avecia Inc
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 Avecia Inc filed Critical Avecia Inc
Publication of EP1639143A2 publication Critical patent/EP1639143A2/en
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • C21D6/04—Hardening by cooling below 0 degrees Celsius
    • 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
    • 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
    • C22F1/10—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of nickel or cobalt or alloys based thereon
    • 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

Definitions

  • the present invention concerns a process for improving the corrosion resistance of metals, particularly steels, and especially high Ni alloys.
  • Cryogenic tempering either shallow or deep, but especially the latter, has attracted much attention recently as a means of increasing the life of cutting tools, especially those made from tool steels.
  • cryogenic treatment can improve the corrosion resistance of metals.
  • a process for improving the corrosion resistance of a metal comprising subjecting said metal to a cryogenic treatment.
  • Metals which can be subjected to the process according to the present invention include steels, especially stainless steels, such as for example austenitic stainless steels, including high nickel stainless steels, such as those available under the trade name INCOLOY, and duplex stainless steels.
  • High nickel stainless steels commonly comprise at least 5% w/w Ni, typically at least 8% w/w Ni, and may comprise from 25-30 % w/w Ni.
  • the process is particularly suited to the treatment of high nickel alloys, for example alloys containing at least 50% w/w nickel, and especially to those alloys of the type commercially available under the trade names HASTELLOY, MONEL and INCONEL.
  • the cryogenic treatment of the present invention commonly follows the procedures known in the art for the cryogenic tempering of tool steels, and generally comprises cooling the metal to substantially sub-ambient temperatures, and returning the metal to ambient temperature.
  • the cooling may be carried out rapidly, by for example immersion of the metal in a liquid of selected temperature.
  • this may induce undesirable transformations in the metal as a result of thermal shock.
  • it is preferred that the temperature of the metal is reduced in a controlled fashion to avoid thermal shock.
  • the metal may be maintained at the selected sub-ambient temperature for a period, which may range from several, such as 5 to 30 minutes, to many hours, for example 36-48 hours, depending for example on the temperature, the nature of the metal and the size and volume of the metal.
  • cryogenic treatment effects cryogenic stress relief of the metal, reducing the occurrence of stress cracks, and hence improving the corrosion resistance of the metal.
  • the process may employ shallow cryogenic treatment, for example where the sub- ambient temperature employed is in the range of from -60°C to -90°C.
  • shallow cryogenic treatment typically comprise cooling the metal by exposure to vapours from boiling liquid nitrogen.
  • the process employs deep cryogenic treatment, where the temperature employed is less than -90°C, preferably less than -130°C, and most preferably less than -155°C.
  • the temperature employed is in the range of from -180°C to -195°C, and most advantageously from about -185°C to about -190°C.
  • Such processes typically comprise cooling the metal by exposure to the vapours from boiling liquid nitrogen.
  • the metal is typically enclosed in a vented vessel which is injected with liquid nitrogen. It will be recognised that by feeding liquid nitrogen into the vessel at a controlled rate, the temperature in the vessel is reduced as the liquid nitrogen evaporates upon entry into the vessel, and thereby the metal sample is cooled.
  • the vessel is typically insulated to improve the cooling efficiency.
  • the rate of cooling employed can be selected at the convenience of the user, but in many embodiments is controlled to be in the range of from about 0.2°C/minute to about 2°C/minute, such as from 0.5°C/minute to 1 °C/minute.
  • the metal can be returned to ambient temperature. This may comprise active heating of the metal, or may comprise allowing the temperature of the vessel, and hence the metal, to increase to return to ambient temperature. In many embodiments, the temperature is increases at a rate of from 0.5°C to 10°C per minute, such as from 2°C to 7°C per minute, and preferably at about 5°C per minute.
  • the metal is preferably subjected to a heat treatment, for example mar-tempering employing conventional mar-tempering methodology.
  • the mar-tempering which comprises a cycle of heating and cooling, often repeated several, for example from 2 to 3, times, may be conducted after the metal has been stored at ambient temperature for a period, or may follow immediately the process by which the metal is returned to ambient temperature.
  • the mar- tempering comprises heating the metal to about 120°C to 175°C, preferably about 150°C, followed by cooling to ambient temperature.
  • the process according to the present invention comprises mar-tempering the metal by heating from sub-ambient temperature, preferably about -185°C to -190°C, to about 140°C to 160°C at a rate of from 2 to 7°C, preferably about 5°C, per minute.
  • the cryogenic treatment process can be carried out in commercially available apparatus known for the cryogenic tempering of tool steels. Such apparatus may additionally comprise the facility to effect mar-tempering.
  • the process according to the present invention is especially suited for improving the corrosion resistance of metals employed in the manufacture of filters, heaters, coolers, exchangers, piping, mechanical process equipment and the like.
  • the process may be applied to the metal prior to its fabrication of a given article of commerce, but is preferably applied to the fabricated article.
  • the process is particularly suited to improving the corrosion resistance of metals subjected to chloride corrosion. Examples of particular articles of commerce include especially heat exchanger tubes, cooler tubes, process piping, especially chemical process piping, filters, pumps, reactor vessels and storage tanks.
  • a metal having a given corrosion resistance or an article made from such a metal, can be selected to have the corrosion resistance improved, wherein the corrosion resistance is improved by treating the metal cryogenically, preferably the metal being subjected to a deep cryogenic treatment.
  • Hastelloy C276 Schedule 40 pipe was subjected to cryogenic treatment by cooling to -187°C by exposure to liquid nitrogen vapour in a thermally insulated container. Cooling was effected at the rate of 1 °C per minute and the pipes maintained at -187°C for 10 hours. The pipes were then allowed to warm to ambient temperature, and then subjected to mar-tempering by heating to 150°C, and allowing to cool to ambient temperature. The mar-tempering process employed 3 heating/cooling cycles.
  • the pipes were incorporated as heater elements in a reactor vessel employed to heat a benzene and phosphorus trichloride reaction mixture to a reaction temperature of 650°C.
  • the pipes so treated were observed to have a useful life which was at least 8 times longer than the corresponding non-cryogenically treated pipes prepared from the same grade of Hastelloy exposed to the same use conditions.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatment Of Articles (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)

Abstract

A process for improving the corrosion resistance of metals, particularly steels and high nickel content alloys, is provided. The process comprises subjecting metal parts to one or more cryogenic treatment, optionally followed by one or more heat treatments. Cryogenic treatment preferably employs temperatures of between -90°C to -195°C, most preferably -180°C to -195°C. Heat treatment preferably employs temperatures of between l20°C to 175°C. The process may be employed in the treatment of metal parts and components. Heat exchanger tubes, cooler tubes, piping, especially chemical process piping, pumps, reactor vessels and storage tanks produced by a process are provided.

Description

PROCESS FOR IMPROVING THE CORROSION RESISTANCE OF METALS
The present invention concerns a process for improving the corrosion resistance of metals, particularly steels, and especially high Ni alloys.
Cryogenic tempering, either shallow or deep, but especially the latter, has attracted much attention recently as a means of increasing the life of cutting tools, especially those made from tool steels.
Surprisingly, it has now been found that cryogenic treatment can improve the corrosion resistance of metals.
According to the present invention, there is provided a process for improving the corrosion resistance of a metal, said process comprising subjecting said metal to a cryogenic treatment.
Metals which can be subjected to the process according to the present invention include steels, especially stainless steels, such as for example austenitic stainless steels, including high nickel stainless steels, such as those available under the trade name INCOLOY, and duplex stainless steels. High nickel stainless steels commonly comprise at least 5% w/w Ni, typically at least 8% w/w Ni, and may comprise from 25-30 % w/w Ni. The process is particularly suited to the treatment of high nickel alloys, for example alloys containing at least 50% w/w nickel, and especially to those alloys of the type commercially available under the trade names HASTELLOY, MONEL and INCONEL. The cryogenic treatment of the present invention commonly follows the procedures known in the art for the cryogenic tempering of tool steels, and generally comprises cooling the metal to substantially sub-ambient temperatures, and returning the metal to ambient temperature. The cooling may be carried out rapidly, by for example immersion of the metal in a liquid of selected temperature. However, in many embodiments, this may induce undesirable transformations in the metal as a result of thermal shock. Accordingly, it is preferred that the temperature of the metal is reduced in a controlled fashion to avoid thermal shock. The metal may be maintained at the selected sub-ambient temperature for a period, which may range from several, such as 5 to 30 minutes, to many hours, for example 36-48 hours, depending for example on the temperature, the nature of the metal and the size and volume of the metal.
Without wishing to be bound by any theory, it is believed that the cryogenic treatment according to the present invention effects cryogenic stress relief of the metal, reducing the occurrence of stress cracks, and hence improving the corrosion resistance of the metal. The process may employ shallow cryogenic treatment, for example where the sub- ambient temperature employed is in the range of from -60°C to -90°C. Such processes typically comprise cooling the metal by exposure to vapours from boiling liquid nitrogen. In many embodiments, it is preferred that the process employs deep cryogenic treatment, where the temperature employed is less than -90°C, preferably less than -130°C, and most preferably less than -155°C. It is especially preferred that the temperature employed is in the range of from -180°C to -195°C, and most advantageously from about -185°C to about -190°C. Such processes typically comprise cooling the metal by exposure to the vapours from boiling liquid nitrogen. The metal is typically enclosed in a vented vessel which is injected with liquid nitrogen. It will be recognised that by feeding liquid nitrogen into the vessel at a controlled rate, the temperature in the vessel is reduced as the liquid nitrogen evaporates upon entry into the vessel, and thereby the metal sample is cooled. The vessel is typically insulated to improve the cooling efficiency.
The rate of cooling employed can be selected at the convenience of the user, but in many embodiments is controlled to be in the range of from about 0.2°C/minute to about 2°C/minute, such as from 0.5°C/minute to 1 °C/minute.
After storage for the desired period of time, the metal can be returned to ambient temperature. This may comprise active heating of the metal, or may comprise allowing the temperature of the vessel, and hence the metal, to increase to return to ambient temperature. In many embodiments, the temperature is increases at a rate of from 0.5°C to 10°C per minute, such as from 2°C to 7°C per minute, and preferably at about 5°C per minute. After returning to ambient temperature, the metal is preferably subjected to a heat treatment, for example mar-tempering employing conventional mar-tempering methodology. The mar-tempering, which comprises a cycle of heating and cooling, often repeated several, for example from 2 to 3, times, may be conducted after the metal has been stored at ambient temperature for a period, or may follow immediately the process by which the metal is returned to ambient temperature. In embodiments, the mar- tempering comprises heating the metal to about 120°C to 175°C, preferably about 150°C, followed by cooling to ambient temperature.
In many preferred embodiments, the process according to the present invention comprises mar-tempering the metal by heating from sub-ambient temperature, preferably about -185°C to -190°C, to about 140°C to 160°C at a rate of from 2 to 7°C, preferably about 5°C, per minute.
The cryogenic treatment process can be carried out in commercially available apparatus known for the cryogenic tempering of tool steels. Such apparatus may additionally comprise the facility to effect mar-tempering. The process according to the present invention is especially suited for improving the corrosion resistance of metals employed in the manufacture of filters, heaters, coolers, exchangers, piping, mechanical process equipment and the like. The process may be applied to the metal prior to its fabrication of a given article of commerce, but is preferably applied to the fabricated article. The process is particularly suited to improving the corrosion resistance of metals subjected to chloride corrosion. Examples of particular articles of commerce include especially heat exchanger tubes, cooler tubes, process piping, especially chemical process piping, filters, pumps, reactor vessels and storage tanks. In the process of the present invention, a metal having a given corrosion resistance, or an article made from such a metal, can be selected to have the corrosion resistance improved, wherein the corrosion resistance is improved by treating the metal cryogenically, preferably the metal being subjected to a deep cryogenic treatment.
The process of the present invention is now illustrated without limitation by the following example.
Example
Hastelloy C276 Schedule 40 pipe was subjected to cryogenic treatment by cooling to -187°C by exposure to liquid nitrogen vapour in a thermally insulated container. Cooling was effected at the rate of 1 °C per minute and the pipes maintained at -187°C for 10 hours. The pipes were then allowed to warm to ambient temperature, and then subjected to mar-tempering by heating to 150°C, and allowing to cool to ambient temperature. The mar-tempering process employed 3 heating/cooling cycles.
The pipes were incorporated as heater elements in a reactor vessel employed to heat a benzene and phosphorus trichloride reaction mixture to a reaction temperature of 650°C. The pipes so treated were observed to have a useful life which was at least 8 times longer than the corresponding non-cryogenically treated pipes prepared from the same grade of Hastelloy exposed to the same use conditions.

Claims

1. A process for improving the corrosion resistance of a metal, said process comprising subjecting said metal to cryogenic treatment.
2. A process according to claim 2, wherein the metal is a high Ni-alloy.
3. A process according to either preceding claim, wherein the cryogenic treatment takes place at a temperature of from -180°C to -195°C.
4. A process according to any preceding claim, wherein the cryogenic treatment comprises cooling the metal by exposure to vapour from boiling liquid nitrogen.
5. A process according to any preceding claim wherein the cryogenic treatment is repeated a number of times.
6. A process according to any preceding claim, wherein after cryogenic treatment the metal is exposed to heat treatment.
7. A process according to claim 6, wherein the heat treatment takes place at a temperature of from 120°C to 175°C.
8. A process according to any preceding claim, wherein the metal comprises heat exchanger tubes, cooler tubes, piping, especially chemical process piping, filters, pumps, reactor vessels and storage tanks.
9. Heat exchanger tubes, cooler tubes, piping, especially chemical process piping, pumps, reactor vessels and storage tanks produced by a process according to claim 8.
10. Use of cryogenic treatment to improve the corrosion resistance of a metal.
EP04734559A 2003-05-27 2004-05-24 Process for improving the corrosion resistance of metals Withdrawn EP1639143A2 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US47318903P 2003-05-27 2003-05-27
PCT/GB2004/002232 WO2004106559A2 (en) 2003-05-27 2004-05-24 Process for improving the corrosion resistance of metals

Publications (1)

Publication Number Publication Date
EP1639143A2 true EP1639143A2 (en) 2006-03-29

Family

ID=33490571

Family Applications (1)

Application Number Title Priority Date Filing Date
EP04734559A Withdrawn EP1639143A2 (en) 2003-05-27 2004-05-24 Process for improving the corrosion resistance of metals

Country Status (4)

Country Link
EP (1) EP1639143A2 (en)
JP (1) JP2007503528A (en)
CN (1) CN1795278A (en)
WO (1) WO2004106559A2 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2887558B1 (en) 2005-06-28 2007-08-17 Aubert & Duval Soc Par Actions MARTENSITIC STAINLESS STEEL COMPOSITION, PROCESS FOR MANUFACTURING A MECHANICAL PART THEREFROM, AND PIECE THUS OBTAINED
ITUA20165254A1 (en) * 2016-06-28 2017-12-28 Antonino Rinella CRIOTEMPRATI METALLIC MATERIALS, EQUIPPED WITH A HIGH ABILITY TO ABSORB ENERGY OF ELASTIC DEFORMATION, INTENDED FOR THE CONSTRUCTION OF PROTECTIVE REINFORCEMENT FOR PERFORATING RESISTANT TIRES AND LACERATIONS.

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3891477A (en) * 1971-09-09 1975-06-24 Mangrove Enterprise Inc Material treatment by cryogenic cooling
US4739622A (en) * 1987-07-27 1988-04-26 Cryogenics International, Inc. Apparatus and method for the deep cryogenic treatment of materials
US5761974A (en) * 1996-07-22 1998-06-09 Board Of Regents Of The University Of Nebraska System and method for machining heat resistant materials
US5875636A (en) * 1997-10-01 1999-03-02 Nu-Bit, Inc. Process for the cryogenic treatment of metal containing materials

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2004106559A3 *

Also Published As

Publication number Publication date
WO2004106559A2 (en) 2004-12-09
JP2007503528A (en) 2007-02-22
WO2004106559A3 (en) 2005-03-24
CN1795278A (en) 2006-06-28

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