US3681150A - Fast cold quench oil for metals - Google Patents

Abstract

A QUENCH OIL OF HIGH QUENCHING SPEED PARTICULARLY USEFUL FOR THE QUENCHING OF STEEL COMPRISES A MAJOR PROPORTION OF A HYDROCARBON OIL OF LUBRICATING OIL VISCOSITY RANGE AND A MINOR PROPORTION OF A PETROLEUM HYDROCARBON RESIN THAT HAS BEEN TREATED WITH A FINE DISPERSION OF METALLIC SODIUM OR REALTED ALKALI METAL.

Description

United States Patent U.S. Cl. 148-29 5 Claims ABSTRACT OF THE DISCLOSURE A quench oil of high quenching speed particularly useful for the quenching of steel comprises a major proportion of a hydrocarbon oil of lubricating oil viscosity range and a minor proportion of a petroleum hydrocarbon resin that has been treated with a fine dispersion of metallic sodium or related alkali metal.

BACKGROUND OF THE INVENTION This invention concerns an improved high speed quenching oil composition for use in the heat treatment of metals, particularl ferrous metals such as steel. The invention also concerns improvements in the method of quenching metals with the improved composition of the lnvention.

Many metal alloys, particularly ferrous alloys and carbon steels, require heat treatment to develop the desired degrees of hardness and strength. The basic heat treatments are generally hardening by quenching and softening by annealing. The hardness of an alloy is mainly dependent upon the formation of a certain physical structure. In the case of steel, for example, it is desirable to form martensite in the steel. The hard martensite structure is particularly suited for such metal parts as gears. To increase the hardness of metal alloys such as steel they are heated to an elevated temperature; for example, above 1600 F. and then plunged into a comparatively cool quenching medium. In some cases the desired structure can be obtained immediately, but in other cases the metals are quenched to maximum hardness and then tempered to achieve the desired hardness and ductility.

In the heat treatment of steel the term quenching covers the process of cooling the steel from the temperature range at which austenite (solid solution of carbon in gamma iron) is formed to a temperature below the critical temperature, which is around 1000 F. If the steel is cooled too slowly, the austenite is transformed into the softer pearlite. If the cooling is sufliciently rapid, however, the harder martensite is formed instead. Quenching that is effective in forming martensite is frequentl referred to as marquenching.

The quenching problem is basically one of heat trans fer. While water can be used for rapid quenching, it is undesirable in most instances, because it tends to cool the metal too quickly and often results in distortion and cracking. Hydrocarbon oils, and particularly mineral oils, are commonly used as quenching liquids, but unmodified straight mineral oils do not usually form satisfactory quenching media, since the initial rate of cooling is too slow. Hence, the development of the quench oil art has been in the direction of modifying hydrocarbon oils by incorporating certain additives therein. See for example U.S. Pats. 3,027,315; 3,113,054; 3,159,510 and 3,205,100.

3,681,150 Patented Aug. 1, 1972 ice A particularly eifective quench oil known to the prior art comprises a major proportion of a hydrocarbon lubricating oil and a minor proportion of a petroleum hydrocarbon resin. Such resins are naturally occurring in paraffin base or Pennsylvania type oils, and are obtained therefrom by solvent precipitation, e.g. with propane. Such resins are distinguished from the resins that are obtained by polymerizing steam cracked naphtha streams. The petroleum resins utilized in the present invention are obtained by treating a residual fraction of a paraffinic crude oil such as a Pennsylvania crude oil with an excess of liquid propane or related light hydrocarbon under pressure at ambient temperatures. One common procedure for obtaining such resins has included the steps of dissolving one volume of Pennsylvania reduced crude in about two volumes of liquid propane, cooling the solution by evaporating some of the propane, removing paraffin war: that is thereby caused to separate from the oil, adding further propane up to about 10 volumes per volume of oil, and mildly heating the solution under pressure. This causes the precipitation of a resinous product of high molecular weight in the form of a heavy viscous material of dark color having a viscosity of about 1,000 SUS at 210 F. This resinous product per se is well known in the prior art. While the precise composition of such petroleum resin is not fully known it is an essentially neutral product substantially free of acidic material. See for example, U.S. Pat. 2,614,991.

Fairly satisfactory quenching oils have been prepared in the prior art by adding from 1 to 10% by weight of such petroleum resins to a low viscosity hydrocarbon base oil. One such prior art composition has consisted of about 5 wt. percent of a hydrocarbon resin of about 2800 SUS viscosity at 210 F. in a refined lubricating oil having a viscosity of about 35 to 38 SUS at 210 F. In some applications of this composition the quenching speed has not been sufficiently high to be entirely satisfactory. The quenching speed can be increased slightly by employmg resins of higher viscosity. This adds to the cost of the composition since the higher viscosity resins demand a higher price than the lower viscosity resins. Moreover, the improvement in quenching speed through the use of this expedient is minimal, being in the order of 1 second at best.

DESCRIPTION OF THE INVENTION In accordance with the present invention it has been found that the ability of a petroleum resin to increase the quenching speed of a quench oil base stock can be improved by treating the resin with a fine dispersion of an alkali metal, which can be potassium or lithium but is preferably sodium because of its lower cost.

The amount of alkali metal that is used to treat the petroleum resin will range from about 0.2 to about 5 wt. percent, or more usually from about 0.3 to about 3 vvt. percent based on the resin. For example, desirable products are obtained by treating a resin with about 1% to 1.5 wt. percent of sodium. It is simply necessary to disperse the finely divided alkali metal in the somewhat warmed resin with the aid of a homogenizer or equally efiective equipment and then heat the mixture to about 250 to 450 F. for from about /2 to 4 hours, for example at 300 F. for from about 30 minutes to 2 hours. Alternatively, the finely divided alkali metal can be dispersed in a portion of the base oil that is to be used for making the quench oil, after which the required amount of the mixture of metal and base oil is added to the resin and the above-described procedure is continued.

The petroleum resin employed in the present invention will be a resinous material having a viscosity in the range of about 1000 to 10,000 SUS at 210 F. and preferably a viscosity of from about 2500 to 5000 SUS at 210 F. The resin is of the type that is obtained by propane precipitation from a Pennsylvania type paraflinic petroleum oil residue, as discussed above.

The lubricating oil which forms the major component of the quench oil is preferably a refined mineral lubricating oil having a viscosity in the range of from about 50 to 2000 SUS at 100 F., usually about 100 to 1000 SUS at 100 F. Viscosities at 210 F. of the base oil will be in the range of about 30 to 100 SUS. Preferably the initial boiling point of the oil should be at least 600 F. The quench oil composition will comprise the base oil containing from about 1 to about 10% by weight of the treated resin.

The nature of this invention and the advantages gained from its practice will be more clearly understood when reference is made to the following examples, which include a preferred embodiment.

Example 1 A petroleum resin obtained by propane precipitation from a residuum of a Pennsylvania crude oil was employed for this example. The resin was identified as Pennzoil Resin 2800. This was a black viscous material having a viscosity of about 2800 SUS at 210 F. A quantity of this resin was treated with 1.4 wt. percent of sodium in the following manner. A dispersion consisting of 90 wt. percent of the quench oil base stock described below and 10 wt. percent of sodium was prepared by placing the base stock in a Manton-Gaulin homogenizer and heating it to the melting point of sodium, i.e. about 98-100 C., then dropping the sodium in the form of thumbnail-size lumps into the heated oil and circulating the mixture through the homogenizer. Then a portion of the resulting dispersion was reacted with the resin in a proportion calculated to react 1.4 wt. percent of sodium with the resin. This reaction was run at 300 F. for 2 hours. The sodium treated resin was then blended into additional quench oil base stock to make a quench oil composition. The quench oil base stock consisted of about equal volumes of a 72 V1. refined lubricating oil of 34 SUS viscosity at 210 F. and a 77 VI. parafiinic base stock of 39 SUS viscosity at 210 F. The completed quench oil composition consisted of 5 wt. percent of the sodium treated resin and 95 wt. percent of the quench oil base stock.

For comparative purposes a similar quench oil was prepared using 95 wt. percent of the same base stock and 5 wt. percent of the untreated Pennzoil Resin 2800. The quenching power of each of the quench oils was evaluated using the General Motors Magnetic Quenchometer. The General Motors Magnetic Quenchometer test takes advantage of the fact that some metals lose their magnetism when heated above a critical temperature known as the Curie point and regain magnetism when cooled below the critical temperature. High purity nickel with 'a Curie point of about 670 F. is ordinarily used in this test as the metal because of its non-scaling characteristics and its resistance to cracking upon repeated heating and cooling. A spherical nickel specimen having a diameter of inch and weighing about 50 grams is used in these tests and the surface of the nickel balls is protected from the oxidizing atmosphere with a surface layer of diffused chromium. The nickel sphere is heated to 1550 F. and then plunged into 200 cc. of the quench medium being used, the quench medium being surrounded by a magnetic field. The temperature of the quench oil is initially 140 F. A special timing device determines the quenching TABLE I Oil tested: Quench time (seconds) Base oil 22.5 Base oil 5% resin (untreated) 14.2 Base oil 5% sodium-treated resin 11.5

It will be noted from the data that the base oil had a quench time of 22 to 23 seconds, which is too slow for many purposes. The petroleum resin reduced the quenching time to 14.2 seconds. Treating the resin with sodium caused a further reduction in quenching speed to 11.5 seconds. Thus, by employing the present invention there was a decided improvement in quenching speed as compared to the prior art composition.

Example 2 (comparative example) A quench oil was prepared by blending 5 wt. percent of an asphalt having a softening point of 130 F. with wt. percent of the same base oil used in Example 1. A second quench oil was prepared by using instead of the asphalt itself an equal amount of the same asphalt that had been treated with sodium in the same manner that the petroleum resin of Example 1 was treated with sodium. These two blends were subjected to the quenchometer test described in Example 1. Both of the blends have quenching speeds of from 11 to 12 seconds. Thus, treating the asphalt with sodium gave no measurable change in quenching speed. Although it would thus seem that the quench oils containing asphalt would be equally as good as quench oils prepared in accordance with the present invention, quench oils prepared with asphalt have a serious disadvantage because of a tendency to oxidize and form sludge. Thus, the present invention provides a quench oil having a quenching speed as good as that of a quench oil prepared with asphalt which at the same time overcomes some of the disadvantages of the latter type of quench oil (See US. Pat. 3,205,100.)

Although this invention has been described in the preferred embodiments with a certain degree of particularity, it will be understood that there is no intention to limit the invention to the specific examples, as numerous modifica tions and adaptations thereof can be resorted to without departing from the spirit and scope of the invention as defined by the appended claims.

What is claimed is: 1. A quench oil composition comprising a major proportion of a hydrocarbon lubricating oil having a viscosity within the range of about 50 to 2000 SUS at F. to which has been added from about 0.3 to 10 weight percent of an alkali-metal-containing additive,

said additive being the result of adding from about 0.2

to 5 Weight percent of an alkali metal to a petroleum resin and heating the mixture to a temperature of from about 250 to 450 F.,

said petroleum resin being obtained by light hydrocarboln treatment of the residuum of a parafiinic crude o1 2. Quench oil composition as defined by claim 1 wherein said additive is the result of adding about 0.3 to 3 weight percent of sodium to said resin.

3. Quench oil composition as defined by claim 1 wherein said alkali metal is sodium.

4. Quench oil composition as defined by claim 1 wherein said resin has a viscosity in the range of from about 1000 to 10,000 SUS at 210 F.

5. In a method of quenching that is useful in the treatment of metals wherein a metal to be treated is heated to an elevated temperature and wherein said heated metal is then rapidly quenched in a quenching medium to bring about desired metallurgical changes in said metal, the improvement which comprises using as said quenching medium a liquid composition as defined by claim 1.

References Cited UNITED STATES PATENTS 2,340,726 2/1944 Horst et a1. 148-18 2,600,290 6/1952 Corneil 148-28 X 2,967,816 1/1961 Hudson 208-44 3,027,315 3/1962 Rodman et al. 148-29 X 3,224,910 12/1965 McEWen 148-28 X 3,489,619 1/1970 Brewster 148-18 X 3,567,640 3/1971 Stroh 148-29 X FOREIGN PATENTS 1,495,862 8/1967 France 148-28 L. DEWAYNE RUTLEDGE, Primary Examiner 10 G. K. WHITE, Assistant Examiner US. Cl. X.R.