US3022205A

US3022205A - Method of quenching and quenching liquid

Info

Publication number: US3022205A
Application number: US735115A
Authority: US
Inventors: Fredeic L Chase; Charles W Ewing
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1958-05-14
Filing date: 1958-05-14
Publication date: 1962-02-20
Anticipated expiration: 1979-02-20

Description

United States Patent 3,022,205 IVIETHOD OF QUENICIHIN G AND QUENCHING Q Frederic L. Chase, Dayton, and Charles W. Ewing, Centerville, Ohio, assignors to General Motors Corporatron, Detroit, Mich., a corporation of Delaware No Drawing. Filed May 14, 1958, Ser. No. 735,115 8 Claims. (Cl. 14820.6)

definite temperature and then cooled. In many of such heat treating operations, the hot metal is cooled more or less rapidly and such rapid cooling operations aregenerally known as quenching. Generally, quenching is accomplished by immersing the hot metal in a bath of a liquid such as water or oil. A common quenching operation is the quenching of steel in water or other aqueous liquids or in oil to harden the'steel.

Water, which is the cheapest quenching liquid and which produces very rapid cooling, is not suitable for quenching many kinds of steel. In many steel heat treatment operations, the steel is quenched in a hycrocarbon oil which gives a relatively slow rate of cooling, which is required to produce certain desired physical properties such as hardness and ductility. Rapid'cooling caused by water quenching in steel'hardening operations results in excessive strains in certain kinds of steel which warp and crack the steel. The slower cooling rate afforded by oil quenching prevents such excessive strains but often does not develop maximum hardness. It, therefore, is desirable to provide quench liquids which will cool the metal at rates intermediate between oil and water quenches, whereby the greatest degree of hardness can be obtained without warping or cracking the steel. Oil quenching is expensive, not only because of the initial cost of the oil, but also because the oil deteriorates in use and must be refined or replaced with fresh oil. The flammable nature of hydrocarbon oils also presents a serious fire hazard in oil quenching operations. The art has long sought for cheap substitutes for oil but without much success. Aqueous solutions of salt or caustic soda, which are used to some extent, provide an even faster rate of cooling than water and are not suitable for use where a cooling rate intermediate between those obtained in water and oil is desired. Various aqueous solutions or dispersions of organic materials such as starch, glue, pectin, natural gums and the like, have been from time to time proposed as steel quenching liquids, but these have not proved successful as substitutes for quenching oils since they are erratic and unpredictable in their quenching properties over even a short period of usage.

It is an object of this invention to provide a new and useful process for quenching metals in heat treating which has no fire hazards, oifensive odors, fumes or foaming problems and which is substantially uniform in quenching effect over long periods of usage, stable, long lived, low in cost, and can be used at various temperatures and can be varied to provide different advantageous quenching rates.

It is another object of this invention to provide an aqueous quenching solution whose strength can be varied to provide a broad range of advantageous predictable quenching rates between the quenching rates of water and oil which rates are substantially uniform over a long period of usage and which has no fire hazards, oifensive odors, fumes or foaming problems and is low in cost,

7 long lived, stable, and can operate at a variety of useful temperatures.

It is another object of this invention to provide such a process and solution with an inexpensive rust inhibitor which will pacify or tranquilize this solution and which will not affect undesirably the process or solution or make the quenching rates erratic. v J

Generically, to attain these and other objects, metal such as carbon steel, oil hardening grade steel or car-, bonized steel are heated above their critical temperature and then quenched in an aqueous solution containing .2 to 4 grams per gallon of water of a high polymer of ethylene oxide having molecular weights from 100,000 up to several million. The concentration is varied inversely according to the rate or speed of quenching desired. No other additive is required in the solution unless the tank and other parts of the quenching apparatus coming into contact with the solution are subject to rust. To prevent rusting of the tank. or other apparatus, a rust inhibitor is used which has a pacifying or tranquilizing action upon the solution so that it does not'makegthe quenching propertie erratic. Suitable rust inhibitors which maybe added are mono-, di-, or tri-ethanolamine in amounts of about /2 by weightor sodium, potassium or amonium borate in amounts of about 1 by weight. These amounts are sufiicient to prevent rusting of the parts and apparatus; I As one specific example of the invention, hexagonal billets, of an inch across the flats and 2%- inchesrlong of SAElCl144 steel, were heated tol52'5 F. and then quenched in a steel tank containing one gallon of aqueous solution whose temperature was kept at F. or below. The critical temperature of this steel is about IAOOYF. The solution contained /2 a gram of a very high polymer of ethylene oxide having a molecular weight of several million known as Polyox 701. Preferably, the solution also contains /2% by weight of triethanolamine, which not only inhibits rusting of the steel tank, but also acts as a pacifier or stabilizer promoting smoothness and quiet, orderly boiling of the solution. This solution and this process uniformly hardened the billets over an extended period of usage, obtaining the desired degree of hardness without warping or cracking. It has no fire hazard, ofiensive odors, fumes or foaming problems. It is lower in cost than any other comparable quenching solution excepting water and can be used without replacement for long periods of time. Therquenching rate is stable and predictable.

To obtain a more rapid quenching rate, a lower concentration solution may be used as low as .2 of a gram per gallon while to obtain a slower quenching rate, a higher concentration solution up to 4 /2 grams per gallon of high polymer ethylene oxide may be used. The desirable concentration of the polymer is less when the molecular weight is high.

When the polymer having molecular weights of several million (Polyox 701) is used, the desirable concentration varies from .2 to 1 gram per gallon.

When polymers of lower molecular weights, such as 1,000,000 to 100,000, are used, higher concentrations are desirable. For the grade Polyox 301, the desirable range is about .6 to 2 grams per gallon. For the grade Polyox 205, the desirable concentration is about 1 to 2 /2 grams per gallon. For the grade Polyox 35, the desirable concentration is about 2V2 to 4% grams per gallon.

If a lower cost solution is desired, borax in an amount of about 1% by weight may be substituted for the triethanolamine. It also has a pacifying and transquilizing effect upon the solution, but this effect is less than the corresponding effect of triethanolamine. The solution also prevents rusting of the steel parts and provides the parts with a thin protective coating.

)2, An improved method for quenching heated metal' which comprises quickly immersing said heated metal in a liquid bath consisting principally of an aqueous solution of a watersoluble high polymerof ethylene oxide and a rust inhibitor, said polymer having a molecular weight between 100,000 and several million. a a

3. An improved method for quenching heated metal which. comprises quickly immersing said heated metal in a liquid bath consisting principally ofan aqueous solution containing between 350 gram and 4% grams of a water soluble high polymer of ethylene oxide per gallon of water having a molecular weight between 100,000 and several million and about one percent by weight of borax.

4. An improved methodfor quenching heated metal which comprises quickly immersing said heated metal in aliquid bathconsisting principally of an aqueous solution borax.

ular weight between 100,000 and several million, and a 'rust inhibitor.

6. A quenching liquid for: the heat treatment of materials consisting essentially of water containing between gram and 4 /2 grams of a high polymer of ethylene oxide per'gallon of water, said polymer having a moiecular weight between 100,000 and several million," and A quenching'liquid for the heat treatment of materials consisting essentially of water'containing between $1 gram and 4 /2 grams of'a polymer of ethylene oxide per gallon of water, said polymer having a molecular weight between'l00,000 and several million.

containing bctwcengi gram and 4 /5 grams of a water soluble high polymer of ethylene oxide'per gallon of water having a molecularrweight between 100,000 and several'millionand about' l percent by weight ofrtriethanolamine.

5; A'quen c'hing liquid for the heat treatment of mat'erialsfconsi'sting essentially of water containing between gidgr'am and 4% grams of a high polymer of ethylene oxide per gallon of water, said polymer having a molec- 8. A quenching liquid for the heat treatment of ma terials consisting essentially of water containing between 3 gram and 4 /2 grams of a polymer ,of ethylene oxide per gallon of water, said polymer having a molecular weight between 100,000 and several million and about /2. percent by weight of triethanolarnine. V

References Cited in the file ofthis patent UNITED STATES PATENTS 2,793,147 Erdmann et a1 May 21, 1957 2,799,606 Freeman July 16, 1957 2,914,491 Bailey Nov. 24, 1959 FOREIGN PATENTS Y 716,354 Great Bri tain" Oct. 6, 1954 OTHER REFERENCES Ethers and Oxides, by Carbide and Carbon Chemicals- Corporation. Pages 12 -13. Library call -Number TP 248; E7. V V

Ucon Booklet by Carbide and-Carbon Chemicals Corporation,j2 0 pages, pages '14, 15 and l7 relied upon. Library c'all Number TP 247 C32.

.Corneil June 10, 1952

Claims

1. AN IMPROVED METHOD FOR QUENCHING HEATED METAL WHICH COMPRISES QUICKLY IMMERSING SAID HEATED METAL IN A LIQUID BATH CONSISTING PRINCIPALLY OF AN AQUEOUS SOLUTION CONTAINING BETWEEN 2/10 GRAM AND 4 1/2 GRAMS OF A WATER SOLUBE HIGH POLYMER OF ETHYLENE OCIDE PER GALLON OF WATER, SAID POLYMER HAVING A MOLECULAR WEIGHT BETWEEN 100,000 AND SEVERAL MILLION.