US1825565A - Method of treating metals and treating agent therefor - Google Patents

Description

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Patented Sept. 29, 1931 UN'ITEDCSTATE'S- PATENT: mw

mm: .1. w'ILson, or AL'IURAS, mm ALAN s. swans, or Los (museum-0mm; s v sun wnson ASBIGNOB .'IO sun EVANS am rnon or nm'rmo mus AND TREATING AGENT Trrmron;

K0 Drawing.

This invention relates to amethod of treating metals whereby'the ductility hardness, toughness, tensile strength an physical durability thereof are increased and/0r The invention particularly relates to a method of treatment whereby metals of various kinds may be rendered more strong and tough. The invention also relates to a new and novel treating agent whereb desirable characteristics may be develope in various metals.

It has been well known that metals such as iron and steel may be surface hardened by the treatment thereof in the presence of charcoal, bone .ash, leather scraps, etc., and that various desirable. characteristics of metals .may be developed by annealing processes. This. invention difierentiates from the prior art, not only by employing a treating agent, but in addition by the employment 0 steps which have not been used heretofore in developing desirable characteristics in metal.

By the term metals, as used herein, reference is made to both ferrous and non-ferrous.

-metals, such as, for example, iron, wrought iron, steel, copper, gun metal, aluminum and the-like. The term also includes various alloys, both ferrous and non-ferrous, such as,

for example, nickel steel, chromium steel, etc.

An object of this invention is to disclose and provide a process whereby the tensile strength of metals may be materiallyincreased. Another object is to disclose and as provide a process whereby metals may be rendered tougher and of greater resistance to rupture.

Another object of this invention is to pro vide a novel treating agent whereby metal 4e may be rendered stronger and harder. Other objects and advantages of this invention will be apparent to those skilled in the art from the following detailed description of its preferred mode of operation and modification greatly improved. Andesitahereinabovere,

Application fi led December 17, 1928. Serial No. 826,897.

ferred to, isapparently an igneous rock hav- 2 ing a very high melting point and consistin of an aluminum silicate. For purposes 0 illustration, a complete analysls of andesite from a deposit in Modoc County, California, is given herein: Percent Silica (S10 42.70 Iron oxide (Fe O 9.3 Alumina (A1 0,) 30.60 Lime (CaO 10.71 Magnesia( g0) 2.53 Manganese dioxide (MnO 0.30 Chromium oxide (Cr- 0 0.04: Phosphorous pentoxide (P 0 0.23 Potassiumoxide K 0 0.06 Sodium oxide e 0; 0.12 Sulfur trioxide (SO 0.42 Loss on ignition 2.83

It is to be understood that the above analysis is merely representative of the general composition of andesite and any mineral of similar composition, or coming within]- the I characteristics of andesite, is embraced by this invention. 1

Andesite, found in Modoc County, California, is a greyish white rock of great hardness and is commonly known in the locality as white metal. This material is preferably .comminuted or disintegrated to a state of fine division in, order to make it adaptable as a treating agent for metal. The disintegrated 0r comminuted andesite may be used alone,

as a treating agent, or it may be mixed with sand, charcoal, or other substantially inert operation is as follows:

The metal to be treated is reduced to a molten condition and the disintegrated andesite then added to the molten metal. The temperature of the metal at this stage will, of course, depend upon the melting point thereof. The treating agent apparently does not as the fusing point of andesite is above 3000. F.

dissolve to any appreciable extent in metals,

As a result, the treatin agent floats on the surface of the metal an ap ears to form a sintered mass, or slag like bo y. From about one-fourth of one percent to about fifteen percent of andesite by weight of metal bein treated. is preferably added. The time o contacting may va from a minute or two to several minutes, or example, from two to thirty minutes. The time of contactingdepends somewhat upon the results whlch it is desired to obtain and upon the quantity of andesite used. The smaller the quantity of andesite the longer the time of contacting necessary in order to produce a given result.

The molten metal may-then be poured into molds and the treating agent skimmed off the top or allowed to remain in the ladle. The molds may be cooled in a normal manner, or they may be buried or allowed to cool in a pit. The cooling, quenching or annealing, after the metal has been in contact with andesite, does not have to be changed from the method of cooling, quenching or annealing customarily carried out when the hereinabove treating agent is not used.

It will be found that as a result of this treatment, the metal is very much harder and of much greater tensile strength and has a much higher-yield point. For example, electrolytic copper was melted by heating to a temperature of about 2200 F., five percent of andesite added thereto, the mixture maintained in contact for about fifteen minutes and the metal poured at-about 2000 F. into molds. The cast metal was maintained in the molds for about fifteen minutes and the caste ings then cooled in air. The ultimate tensile strength in pounds per square inch was increased from 16,360 pounds to 25,967 pounds. The hardness, as determined by the Shore scleroscope was increased forty percent.

The elongation of the test pieces during test was increased from 12.5% to 23%, or a relative increase of about 80%. Furthermore, the treated copper was not so brittle as the untreated. It is to be understood that in order to produce solid copper castings it may be necessary to employ deoxidizing materials so as to remove the gases which may be occluded in the casting. Zinc is very often added to copper castings made in sand moulds, and if zinc in metallic form is used, about three percent, by weight, may be re quired. If the zinc is added as an alloy with copper, such as a yellow brass or a fifty-fifty copper-zinc alloy, then an addition of one percent zinc in this form may result in sound castings, but this will depend to a large extent upon the care with which oxidization is prevented during the melting period.

As another example of the hereinabove described method, pig iron was heated to 2800 F. and about 10% of andesite by The castin air.

weight thereof added thereto while the metal was in molten condition. The metal was allowed to remain in contact with andesite for about three minutes and poured into molds at a temperature of about 2500 F. were allowed to cool the molds for a. ut fifteen minutes and t en in Test specimens made from these castings showed that the untreated metal had a tensile strength of 25,124 pounds per square inch, while the treated metal had a tensile strength of 34,167 pounds. The untreated metal was very brittle and castings could be easily broken by a single blow with a hammer. Castings of the treated metal, however, couldnot be broken even when struck with a sledge hammer. It is to be understood that in all of the examples given herein, a portion of the metal bein treated was subjected to the identical conditions of temperature, time, cooling, etc., that the sample being treated was being subjected to, thereby permitting a direct comparison to be made between treated and untreated metal. 7

Chemical analysis of the treated and untreated pig iron, from the hereinabove described example, showed substantially no reduction in total carbon present, although the treated iron contained about 0.1% more graphitic carbon. Furthermore, the treated iron contained only 1.45% silicon while the untreated contained 1.59% silicon.

Steel castin s have also been treated in accordance wit the method hereinabove described and have shown an increase in tensile strength from 62,000 pounds to 65,000 pounds. llhe steel castings were reduced to a molten condition and while at a temperature of 3200 'F. about two percent in weight of andesite was added to the metal? The time of contact between heated metal and the treating agent was only two. minutes, the treated metal being poured at a temperature of 3000 F. into molds wherein they were cooled for about three hours and then discharged and cooled in air. There was apparently no increase in the hardness of the steel castings, as determined by the sclerosco and there was slight decrease in elongation. The yield point in pounds per square inch wasincreased from 38,296 pounds to 41,704 pounds.

Instead of reducing the metals to a molten condition and then treating them with a treating agent containing andesite We have found that the tensile strength, hardness and toughness of metals can be very materially increased by merely heating the metal to above a red heat and then contacting the heated metal with the treating agent. For example, metallic bodies may be heated to redness, or a temperature above red heat and then covered with the treating agent and allowed to cool, either in contact with said treating gent or the contactin with the treating agent maintained for a short of time and themetal cooled out 0 contact with the treating agents In additionmetallic objects ma be raised. to the proper temperature while in contact with the treating agent, or they may be raised to a temperature above red'heat, covered with the treating agent and then reheated for a period of time depending upon the results desired.

' 'a period of from two to fifteen minutes.

After these steel bodies were taken out and allowed to cool in air, it was found that the yield point had been raised from 35,000 pounds to 44,000 pounds and the ultimate tensile strength in pounds per square inch raised from 42,947 pounds to 73,210 pounds. Structural steel bars heated in a furnace to an orange heat. and then covered with powdered andesite showed an increase in ultimate tensile strength of almost forty percent. The elongation was reduced from 37.5% to 23%. The yield point was increased about 35%.. The surface hardness was very materially increased. By treating nickel steel castings in accordance with this method the elasticity could be. increased from about 15% to 73%and the ultimate tensile strength from 10 to 17%. The yield point could be increased approximately 80%.

When surface dusting heated bodies of metal in carrying out this process it was found advantageous to reheat the metal while in contact with the treating agent. For example, when testing steel, the untreated specimens of which had an ultimatetensile strength of 62,000 pounds per square inch, the treated bars which had not been reheated in contact with the andesite showed an ultimate tensile strength of 7 ,000 pounds per square inch, whereas simil r bars treated with the same quantity of treating agent, but reheated after being covered therewith, showed an ultimate tensile strength of- 71,000 pounds per square inch. Our general conclusions indicate that it is desirable to maintain the metal in contact with the treating agent at as high a temperature as it is economical to use.

As a further modification or adaptation of this process of treating metals, crushed or pulverized andesite may be used, either alone or with molding sand, oil, core oil and core binders in making molds into which molten metals may be poured to make castings which riod The treating.

may be distinshed bi heir greater surface hardness an strengt Furthermore, all metals treated by any of the above described modifications of our process exhibit pronounced rust-resisting properties.

The reason for the results obtained by treat- -ing metals with the treating agent'hereinabove described is not known at present, but there is no uestion but that the tensile strength, har ess and toughness of metals is greatly increased by contacting the metal while in a heated condition with andesite.

-Numerous changes and modifications may be made in the method employed in contactmg metals while in a heated condition with a treating agent containing andesite, and all such changes and modifications as come within the scope of the following claims are embraced thereby.

We claim: y 1. In a process of treating metals the steps of heati a metal to above red heat and contactmg t e heated metal in the absence of carbonaceous material with a comininuted material containing andesite. 2. In a process of treating metal, the steps of heating metal to above red heat, placing a comminuted materialfree of carbon containmg andesite in contact therewith, and then 'heatin the metal and material in contact therewlth together. a

3. In a process of treating metals, the steps of heating a metal to above red heat, then contacting the heated metal with a disintegrated material substantially free of carbonaceous material but containing andesite and then allowing the metal to cool while in said contact.

4. In a process of treating metals, the steps of heating a metal while in contact with a comminuted material containing andesite in the absence of carbonaceous material.

5. In a process of treating metals, the steps 3 of reducing a metal to molten condition, and contactin a comminuted material containing andesite es of carbon therewith.

6. In a process of treating metals, the steps of reducing a metal to molten condition, adding a preheated comminuted material containing andesite free of carbon thereto and .then removing such comminuted material together with impurities from the metal.

7: In a process of treating metals, the steps of reducing a metal to molten condition, addcarbonaceous material but containing'andesite thereto.

9. In a process of treating metals, the steps of reducing a metal to molten condition, adding from one-half to about fifteen percent by weight of a preheated comminuted andesite free of carbon thereto, and then removing such added andesite together with slag from the molten metal. I

Signed at Alturas, California, this 7th day of December, 1928, by FRANK J. WILSON.

Signed at Los Angeles, California, this 4th day of December, 1928, by ALAN S. EVANS.

FRANK J. WILSON. ALAN S. EVANS.