US3819428A - Metal treatment - Google Patents

Metal treatment Download PDF

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Publication number
US3819428A
US3819428A US00246189A US24618972A US3819428A US 3819428 A US3819428 A US 3819428A US 00246189 A US00246189 A US 00246189A US 24618972 A US24618972 A US 24618972A US 3819428 A US3819428 A US 3819428A
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temperature
process according
metal
liquid
range
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US00246189A
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English (en)
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C Moore
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Priority claimed from GB235272A external-priority patent/GB1353753A/en
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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
    • C21D6/04—Hardening by cooling below 0 degrees Celsius

Definitions

  • Processes for metal hardening generally include several steps of successive heating to elevated temperature and cooling to ambient temperature. Proposals have been made to include also a step in which the metal is cooled to temperatures substantially below C but difficulties have arisen in the methods for effecting this cooling. Direct contact with a cold liquid such as liquid nitrogen imposes severe strains on the metal structure that can only partially be avoided by means of such expedients as wrapping the metal in a protective layer of a material such as paper. Additionally it is believed that known processes have not utilised the optimum temperature range for the sub-zero cooling step, cooling to the temperature of liquid nitrogen (196 C) being unduly low for most purposes. Another important factor is the stage in the hardening process at which the subzero cooling step is performed.
  • the invention provides a metal hardening process in which the metal is, in sequence, heated to an elevated temperature; quenched to a temperature not less than ambient", cooled slowly to a temperature within the range 80 to l20C by means of liquefied gas in a zone which is initially at or near ambient temperature or by means of cold gas; allowed to return to ambient temperature; tempered at elevated temperature; and cooled to ambient temperature.
  • the manner in which the initial heating is conducted is chosen according to the metal being treated.
  • the initial heating is normally effected by preheating to a temperature of the order of 650 to 900C followed by heating for a short period (say 1 to 5 minutes) to a temperature in the range 750 to l,325C.
  • the quenchant is normally at a temperature initially in the range ambient to 500C. Gases such as air or nitrogen can be used. Suitable liquid quenchants for use at such temperatures include various oils and molten salts. Any residual oil or salt on the metal should preferably be removed prior to cooling to the temperature in the range 80 to lC. if the quenchant is at a temperature above ambient the quenched metal should be allowed to cool to ambient temperature before being transferred to the cooling zone. The period between reaching ambient temperature and introduction into the cooling zone should preferably not exceed 3 hours and preferably is as short as possible so as to minimise stabilisation of austenite.
  • the metal should preferably be retained at the chosen temperature in the range 80 to l20C for a period of at least the same duration as that of cooling from ambient to the chosen temperature. In order to return to ambient temperature the metal is then preferably left to stand in air at ambient temperature.
  • the cooling zone is a liquid bath cooled by liquefied gas.
  • the bath can be cooled by cold gas evolved from a liquefied gas.
  • Suitable liquids for the liquid bath include low melting organic liquids such as acetone.
  • Suitable liquefied gases for cooling the second bath include liquid nitrogen, liquid oxygen and liquid argon. Liquid nitrogen is generally preferred.
  • the liquefied gas is preferably contacted indirectly with the bath liquid, for example by passing the liquefied gas through a pipe or coil immersed in the liquid.
  • the liquefied gas can be introduced directly into the liquid, preferably accompanied by agitation of the liquid.
  • Slow cooling is necessary to ensure that an unduly high temperature difference is not created between adjacent layers of the metal.
  • the rate at which the second liquidbath should be cooled is dependent upon the thickness and thermal conduc tivity of the metal being treated.
  • the bath is preferably cooled from 15C to l 10C over a period of about 10 minutes.
  • the metal directly with cold gas it is preferred to contact the metal directly with cold gas.
  • the cold gas is preferably formed by evaporating liquefied gas. Nitrogen is preferred.
  • the gas cooling zone is preferably in a cold box which can be loaded with the workpiece from the front.
  • a cold gas is employed it is desirably introduced in such a manner as to give good contact with the surface of the metal being cooled.
  • the temperature of the gas and the rate at which it is introduced into the cooling zone can be readily selected to give a suitable rate of cooling.
  • the tempering is normally conducted at a temperature within the range 150 to 600C for a period of onehalf to 2 hours, the particular temperature and period being selected according to the composition and crosssection of the workpiece.
  • the process of the invention gives in a single tempering stage a degree of hardness at least equal to that formerly achieved with several tempering stages.
  • the process of the invention is well suited to the hardening of precipitation hardening alloys such as those of magnesium or aluminium, and is particularly useful for the hardening of steels, especially for tool steels.
  • the steps of the procedure following the initial heating at elevated temperature have the effect of reducing the proportion of austenite and improving the nature of precipitated alloy carbides in the steel.
  • a temperature below C promotes break-down of the austenite molecules, even through the rate of breakdown decreases with decreasing temperatures, but substantially halts the precipitation of alloy carbides.
  • alloy carbides are precipitated into a steel having a very low austenite content and as a result give a product of improved hardness.
  • a temperature below I 20C is to be avoided. It may cause undue stress in the metal structure and further, practical difficulty is encounted in finding for the liquid bath a material that remains in the liquid state at temperatures below l20C.
  • the process of the invention is advantageous in that it is quicker and requires less energy than a procedure that requires more than one tempering step. Moreover it gives a product that is more resistant to flaking than a product obtained by a process including a conventional cold treatment.
  • the invention includes within its scope metal that has been treated by the process of the invention.
  • Example 1 Samples of tool steel having the composition, by weight, of 18% tungsten, 4 percent chromium and 1 percent vanadium were hardened according to (a) a conventional treatment and (b) the process of the invention. The samples each measured 2 X /2 X /2 overall, had the tool angles (ISO) 0, 15, 10, 5, 15, 20 and a noze radius of 0.015 inches.
  • the tools treated by the conventional method were preheated at 850C, hardened at 1,280C for two minutes and quenched in a hot oil bath at 250C. They were then cooled in air to 18C and cleaned to remove residual oil. Finally they were twice subjected to a tempering at 550C for one hour, in each case followed by cooling in air.
  • the tools treated by the method of the invention were also preheated at 850C, hardened at 1,280C for 2 minutes, quenched in a hot oil bath at 250C and cooled in air for 30 minutes. They were then cleaned to remove residual oil and inserted in an acetone bath at 18C. The acetone bath was provided with a coil through which liquid nitrogen was passed slowly so as to cool the acetone to lC in minutes.
  • the acetone temperature was maintained at 100C for a further 10 minutes by passing a very small amount of liquid nitrogen through the coil to to balance the warming effect of the surroundings and the tools were then removed and allowed to stand in air for 30 minutes to return to ambient temperature (18C). They were finally subjected to a single tempering at 550C for 1 hour and air cooled.
  • a comparative test was then effected using the method and apparatus of RA Billets UK Pat. No. 1,190,072
  • a bar of free cutting ENlA steel was placed on a lathe and cut by the different tools in turn. The depth of cut was 0.050 inch and the bar was fed to the tool at a rate of 0.004 inch per revolution. The flank wear of the tools over a specified period was then measured and the results are shown in the table.
  • FIG. 1 is a schematic perspective view of a cold box
  • FIG. 2 is a plan view of the cooling apparatus including the cold box shown in FIG. 1;
  • FIG. 3 is a circuit diagram of a liquefied gas supply control system which may be used in conjunction with the apparatus shown in FIG. 2.
  • a cold box 2 is formed of front and rear sections 4 and 6.
  • the interior of the cold box 2 constitutes a cooling zone in which metal being treated by the process of the invention may be cooled to a temperature in the range of 80 to 120C.
  • the cold box 2 has an inlet 10 and an outlet 12 for vaporised liquid gas.
  • An insulated duct 14 enables gas leaving the outlet 12 to be recirculated to the inlet 10, the recirculation being effected by a blower 16 located just upstream of the inlet 10.
  • a pipe 18 leads from a source of liquefied gas (not shown) through the wall of the duct 14 to a sprayer 20 located within the duct 14.
  • a source of liquefied gas not shown
  • the evaporated gas in the duct vaporises the liquid spray in carrying it towards the blower 16.
  • a stream of cold evaporated gas is passed over the workpiece on the batten 8.
  • a vent pipe 22 leads from the duct 14 and has located therealong a pressure relief valve 24 which may be set to open at a chosen pressure.
  • FIG. 3 a system which may be used to control the introduction of liquefied gas through the sprayer 20.
  • a temperature sensing element 26 which may be located at the outlet end of the cold box 8 is in circuit with a thermostat 28.
  • the thermostat 28 may be set such that a solenoid valve 30 controlling the liquid supply to the sprayer 20 remains open until the temperature sensed by the element 26 reaches a chosen minimum.
  • the cold box is constructed from an outer wooden shell and an inner insulating shell of vermiculite which is protected from the cold gas by a lining of aluminium sheet.
  • the internal dimensions of the cold box 2 are 12 by l by 1ft.
  • the workpiece to be cooled is a 10 foot long steel blade.
  • the blade is transferred ready for location in the cold box 2, the lid (front section 4) of the box 2 removed, the blade placed in position within the box 2 and the lid 4 replaced. Passage of liquid nitrogen into the sprayer 20 is then commenced.
  • the thermostat 28 is set so as to effect the cooling in a number of stages. This is to prevent excessively fast cooling. After the blade is cooled to the desired temperature, it is allowed to return to ambient temperature, tempered at elevated temperature and cooled to ambient temperature.
  • a metal hardening process in which the metal is, in sequence, heated to an elevated temperature; quenched to a temperature not less than ambient; cooled slowly to a temperature within the range to C in a region which is initially at or near to ambient temperature by direct contact with cold gas or by indirect contact with cold gas or cold liquid so as to ensure that an unduly high temperature difference is not created between adjacent layers of the metal; allowed to return to ambient temperature; tempered at elevated temperature and cooled to ambient temperature.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Heat Treatments In General, Especially Conveying And Cooling (AREA)
  • Heat Treatment Of Articles (AREA)
US00246189A 1971-04-22 1972-04-21 Metal treatment Expired - Lifetime US3819428A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB235272A GB1353753A (en) 1971-04-22 1971-04-22 Metal hardening process
GB235272 1972-01-18

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US3819428A true US3819428A (en) 1974-06-25

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US (1) US3819428A (enExample)
CH (1) CH584758A5 (enExample)
DE (1) DE2219406A1 (enExample)
FR (1) FR2136621A5 (enExample)

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4482005A (en) * 1984-01-03 1984-11-13 Endure, Inc. Process for treating materials to improve their structural characteristics
US4484988A (en) * 1981-12-09 1984-11-27 Richmond Metal Finishers, Inc. Process for providing metallic articles and the like with wear-resistant coatings
US4756773A (en) * 1985-08-28 1988-07-12 Mg Industries Method for cooling a vacuum furnace
US5591277A (en) * 1995-06-28 1997-01-07 Intri-Plex Technologies, Inc. Method for thermally conditioning disc drive swage mounts
US5865913A (en) * 1995-06-19 1999-02-02 300 Below, Inc. Deep cryogenic tempering process based on flashing liquid nitrogen through a dispersal system
EP1167551A1 (en) * 2000-06-21 2002-01-02 Iwatani International Corp. Sub-zero heat treatment method of steel
US6537396B1 (en) 2001-02-20 2003-03-25 Ace Manufacturing & Parts Company Cryogenic processing of springs and high cycle rate items
US20060081309A1 (en) * 2003-04-08 2006-04-20 Gainsmart Group Limited Ultra-high strength weathering steel and method for making same
CN106319172A (zh) * 2016-08-26 2017-01-11 重庆新钰立金属科技有限公司 汽车配件冷却装置
DE102017007029A1 (de) 2017-07-25 2019-01-31 Messer Group Gmbh Verfahren zur Kältebehandlung von metallischen Werkstücken
DE102018007771B3 (de) * 2018-10-02 2020-02-06 Messer Group Gmbh Verfahren zur Kältebehandlung von Drahtelektroden
DE102018007766A1 (de) * 2018-10-02 2020-04-02 Messer Group Gmbh Verfahren zur Kältebehandlung von Stabelektroden
DE102018007760A1 (de) * 2018-10-02 2020-04-02 Messer Group Gmbh Verfahren zum Verbessern der Stromkontaktierung beim Schweißen mit stromgeführter Drahtelektrode
WO2020126684A1 (de) 2018-12-20 2020-06-25 Messer Group Gmbh Verfahren zum nachbehandeln eines mittels generativer fertigung hergestellten werkstücks

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB8603832D0 (en) * 1986-02-17 1986-03-26 Friction Technology Ltd Forming hard edges on materials
US4739622A (en) * 1987-07-27 1988-04-26 Cryogenics International, Inc. Apparatus and method for the deep cryogenic treatment of materials
US5048162A (en) * 1990-11-13 1991-09-17 Alliant Techsystems Inc. Manufacturing thin wall steel cartridge cases
CN103982751B (zh) * 2014-05-04 2016-06-01 南通天工深冷新材料强化有限公司 一种对管道内高分子耐磨材料进行深冷处理的工艺

Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB491781A (en) * 1936-02-06 1938-09-05 Skf Svenska Kullagerfab Ab Improvements in or relating to the production of anti-friction bearing members of hardened steel
US2445294A (en) * 1945-03-03 1948-07-13 Super Treat Inc Cooling apparatus for treating cutting tools
GB606663A (en) * 1945-04-26 1948-08-18 Bristol Aeroplane Co Ltd Improvements in or relating to chromium-carbon steels for bearing races and to heat treatment processes therefor
US2624688A (en) * 1945-10-27 1953-01-06 Odin Corp Subzero treatment of chromium alloy steel
US2894867A (en) * 1957-07-11 1959-07-14 United States Steel Corp Method of producing transformation hardenable stainless steel and articles produced therefrom
US2978319A (en) * 1959-11-06 1961-04-04 Gen Electric High strength, low alloy steels
US3188248A (en) * 1960-10-28 1965-06-08 Iii William I Bassett Method of effecting an austenite to martensite transformation in a sustained intensity magnetic field
US3223562A (en) * 1961-05-01 1965-12-14 Union Carbide Corp Heat treating process for martensitic transformation alloys
US3282748A (en) * 1964-01-13 1966-11-01 Charles H Martens Weld-strengthening process
US3314831A (en) * 1961-10-26 1967-04-18 North American Aviation Inc Heat treatment for precipitationhardening steels
US3336169A (en) * 1963-05-28 1967-08-15 Uddeholms Ab Method of heat treating high-carbon corrosion resistant steels
US3615920A (en) * 1970-04-16 1971-10-26 Atomic Energy Commission High temperature braze heat treatment for precipitation hardening martensitic stainless steels

Patent Citations (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB491781A (en) * 1936-02-06 1938-09-05 Skf Svenska Kullagerfab Ab Improvements in or relating to the production of anti-friction bearing members of hardened steel
US2445294A (en) * 1945-03-03 1948-07-13 Super Treat Inc Cooling apparatus for treating cutting tools
GB606663A (en) * 1945-04-26 1948-08-18 Bristol Aeroplane Co Ltd Improvements in or relating to chromium-carbon steels for bearing races and to heat treatment processes therefor
US2624688A (en) * 1945-10-27 1953-01-06 Odin Corp Subzero treatment of chromium alloy steel
US2894867A (en) * 1957-07-11 1959-07-14 United States Steel Corp Method of producing transformation hardenable stainless steel and articles produced therefrom
US2978319A (en) * 1959-11-06 1961-04-04 Gen Electric High strength, low alloy steels
US3188248A (en) * 1960-10-28 1965-06-08 Iii William I Bassett Method of effecting an austenite to martensite transformation in a sustained intensity magnetic field
US3223562A (en) * 1961-05-01 1965-12-14 Union Carbide Corp Heat treating process for martensitic transformation alloys
US3314831A (en) * 1961-10-26 1967-04-18 North American Aviation Inc Heat treatment for precipitationhardening steels
US3336169A (en) * 1963-05-28 1967-08-15 Uddeholms Ab Method of heat treating high-carbon corrosion resistant steels
US3282748A (en) * 1964-01-13 1966-11-01 Charles H Martens Weld-strengthening process
US3615920A (en) * 1970-04-16 1971-10-26 Atomic Energy Commission High temperature braze heat treatment for precipitation hardening martensitic stainless steels

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
Reprint from Paperboard Packaging, November 1970. *

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4484988A (en) * 1981-12-09 1984-11-27 Richmond Metal Finishers, Inc. Process for providing metallic articles and the like with wear-resistant coatings
US4482005A (en) * 1984-01-03 1984-11-13 Endure, Inc. Process for treating materials to improve their structural characteristics
US4756773A (en) * 1985-08-28 1988-07-12 Mg Industries Method for cooling a vacuum furnace
US5865913A (en) * 1995-06-19 1999-02-02 300 Below, Inc. Deep cryogenic tempering process based on flashing liquid nitrogen through a dispersal system
US5591277A (en) * 1995-06-28 1997-01-07 Intri-Plex Technologies, Inc. Method for thermally conditioning disc drive swage mounts
EP1167551A1 (en) * 2000-06-21 2002-01-02 Iwatani International Corp. Sub-zero heat treatment method of steel
US6506270B2 (en) 2000-06-21 2003-01-14 Iwatani International Corporation Heat treatment method of steel
US6537396B1 (en) 2001-02-20 2003-03-25 Ace Manufacturing & Parts Company Cryogenic processing of springs and high cycle rate items
US20060081309A1 (en) * 2003-04-08 2006-04-20 Gainsmart Group Limited Ultra-high strength weathering steel and method for making same
CN106319172A (zh) * 2016-08-26 2017-01-11 重庆新钰立金属科技有限公司 汽车配件冷却装置
DE102017007029A1 (de) 2017-07-25 2019-01-31 Messer Group Gmbh Verfahren zur Kältebehandlung von metallischen Werkstücken
DE102017007029B4 (de) 2017-07-25 2019-02-07 Messer Group Gmbh Verfahren zur Kältebehandlung von metallischen Werkstücken
DE102018007771B3 (de) * 2018-10-02 2020-02-06 Messer Group Gmbh Verfahren zur Kältebehandlung von Drahtelektroden
DE102018007766A1 (de) * 2018-10-02 2020-04-02 Messer Group Gmbh Verfahren zur Kältebehandlung von Stabelektroden
DE102018007760A1 (de) * 2018-10-02 2020-04-02 Messer Group Gmbh Verfahren zum Verbessern der Stromkontaktierung beim Schweißen mit stromgeführter Drahtelektrode
WO2020070138A1 (de) 2018-10-02 2020-04-09 Messer Group Gmbh Verfahren zur kältebehandlung von stabelektroden
WO2020070143A1 (de) 2018-10-02 2020-04-09 Messer Group Gmbh Verfahren zum verbessern der stromkontaktierung beim schweissen mit stromgeführter drahtelektrode
WO2020070025A1 (de) 2018-10-02 2020-04-09 Messer Group Gmbh Verfahren zur kältebehandlung von drahtelektroden
DE102018007766B4 (de) 2018-10-02 2022-08-25 Messer Se & Co. Kgaa Verfahren zur Kältebehandlung von Stabelektroden
US12091737B2 (en) 2018-10-02 2024-09-17 Messer Se & Co. Kgaa Method for improved current contacting when welding using a current-carrying wire electrode
WO2020126684A1 (de) 2018-12-20 2020-06-25 Messer Group Gmbh Verfahren zum nachbehandeln eines mittels generativer fertigung hergestellten werkstücks
DE102018010079A1 (de) 2018-12-20 2020-06-25 Messer Group Gmbh Verfahren zum Nachbehandeln eines mittels generativer Fertigung hergestelllten Werkstücks
US11938542B2 (en) 2018-12-20 2024-03-26 Messer Se & Co. Kgaa Method for finishing a workpiece made by additive manufacturing

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Publication number Publication date
DE2219406A1 (de) 1972-11-09
FR2136621A5 (enExample) 1972-12-22
CH584758A5 (enExample) 1977-02-15

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