UNITED STATES PATENT OFFICE. HORACE VAUGHN, OF PROVIDENCE, REODE ISLAND. IMPROVEMENT INTEMPERING AND HARDENING STEEL AND RON.

Specification forming part of Letters Patent No. 19, S04, dated March 30, 1858.

To all whom it may concern: heated. The length of time required for heat: Be it known that I, HoRACE WAUGHN, of ing the articles will depend upon their bulk. the city and county of Providence, and State When the articles have acquired the same tem. of Rhode Island, have invented a new and Im perature as the bath they are taken from it proved Method of Hardening and Tempering and dipped into water, oil, or certain solutions Steel and Iron; and I do hereby declare that in the usual manner. Other articles are then the following is a full and exact description put into the bath and taken out when heated, thereof, and for which a caveat of date Janu the same bath answering for a great number aary 2, 1857, and filed August 5, 1857, has been of operations. filed in the archives of the Patent Office. Pat In some cases the articles to be hardened ented in England December 29, 1856. and tempered are placed in a suitable vessel The nature of my invention consists in heat and the ingredients above mentioned, or oth ing the articles to be hardened, and tempered ers possessing the same or similar properties, in a bath composed of certain chemical agents are put into the vessel with the articles. The or ingredients in a state of igneous fusion, from whole are then placed in the furnace and which bath the articles to be hardened and tem heated until the ingredients are in a state of pered are removed, when sufficiently heated, igneous fusion. The articles are then removed and dipped into water, oil, or certain solutions from the vessel and dipped into Water, oil, or in the usual manner. w certain solutions in the usual manner, as de To enable others skilled in the art to make scribed. The bath thus formed is ready for and use my invention, I will proceed to the continued operation. necessary description. In preparing a bath suitable for hardening In performing my invention the chemical wrought-iron I take twenty-five per cent. of agentsoringredients required for making a bath prussiate of potash, sixty-five per cent. of chlo suitable for hardening and tempering articles of ride of sodium, and ten per cent. of bichromate steel consist of bichromate of potash, chloride of potash, and add thereto bone-dust or ani of sodium, and prussiate of potash, mixed to mal charcoal or a mixture of both. These in gether in the proportions of two pounds of bi gredients must all be pulverized They are chromate of potash, twelve pounds, chloride then placed in a suitable vessel or crucible of sodium, and four pounds of prussiate of and heated until they are in a state of igneous potash. The quantity of prussiate of potash fusion. The articles to be hardened are then may be diminished by adding some ground put in the vessel or crucible, and the whole bone or pulverized animal charcoal to the above may be covered with powdered wood-charcoal ingredients. These ingredients, after being to prevent the escape of the gases, to add to pulverized and mixed together, are placed in the hardness. When the articles have been a box of iron, or into a vessel of any other suit in the bath a sufficient time to carbonize the able material and of the required shape, which iron they are taken out and dipped into Wa is put into a furnace similar to those used for ter or any prepared solution, as usual. In pre heating crucibles, or for case-hardening or for paring the above bath the quantity of prussi. other purposes; or the vessel in which the bath ate of potash may be increased or reduced by is made may be heated in any other manner. adding more bone-dust or animal charcoal, I prefer to cover the ingredients with pounded and instead of ten per cent of bichromate of wood-charcoal to prevent the escape of the potash five per cent. of it, with five per cent, gases during the process of heating; or the of borax, may be used. pounded wood-charcoal, as it possesses hard When the articles have been removed from ening qualities, may be mixed with the other the bath others may be put in, as before de ingredients. The vesselis heated until the in scribed. & gredients are in a state of igneous fusion, When articles of cast-iron or malleable cast a thereby forming a bath into Which the articles iron are to be hardened I prepare the bath in to be hardened and tempered are plunged and the manner above described in reference to allowed to remain until they are sufficiently hardening articles of Wrought-iron; but I re

2 - 9, S04 duce the quantity of animal charcoal or bone say, heating a second time to render the steel dust and increase the proportion of chloride less brittle-is in most cases dispensed with. of sodium. Fourth. The ingredients of which the bath is As bone-dust, animal charcoal, and Wood composed become chemically combined with charcoalhave before been employed for harden the articles of steel, cast-iron, wrought-iron, or ing purposes I wish it to be understood that I malleable cast-iron, and impart a certain de make no claim thereto, except when used in gree of toughness to them, which in most cases combination with chemical agents or ingredi is very beneficial. ents to form a bath in a state of igneous fusion. . Fifth. When articles of wrought-iron, cast It is sometimes desirable to heat articles to iron, or malleable cast-iron are hardened ac be hardened and tempered before they are cording to this improved method the harden plunged into the baths above described. The ing pentrates deeper than in the usual mode object of this is to economize time in the op of case-hardening in the same length of time. eration. This preliminary heating of the ar And, lastly, a great saving of time is effected, ticles may be effected by placing then in a fur as the vessel containing the bath may be large nace or a smith's fire, or otherwise. enough to contain any convenient number of In these specifications I have given the prin articles, which are taken out of the bath and ciples of the invention; but the operator will dipped into the water or oil, or other solution have to exercise judgment in their application. in succession. In hardening polished articles He should avoid particularly the use of wet of steel the bichromate of potash may be re tongs or other tools which will convey water duced in quantity or entirely omitted, and car to the bath. bonate of potash and borax, combined in equal The above-mentioned ingredients are those proportions or used separately, may be en which Iconsider best; but I do not confinemy ployed in its stead in order to prevent the said self strictly to the foregoing proportions or ma articles from being colored by the process of terials, as others of a similar and cheaper char hardening, the said bichromate of potash hav acter may be used, but with a less effect. ing a tendency to injure the color of the articles For hardening steel files and spindles for to be hardened. cotton and woolen machinery and some kinds Eaving thus described the nature of my in of edge-tools I make a bath of chloride of so vention and the manner of performing the dium alone, or mix saltpeter or any of the pot same, I wish it to be distinctly understood that ashes with it, or else borax or soda with or in preparing the baths, as described, I do not without ground bone. confine myself to the proportions given, nor to For hardening iron, chloride of sodium with the ingredients named, as the proportions may prussiate of potash in a state of igneous fusion, be varied according to the particular object for with or without the substances heretofore men which the bath is intended, and other ingredi tioned, will answer to a certain extent. ents possessing the same or similar chemical Cast-iron and steel tools may be lhardened properties may be employed. I would also re by any of the foregoing preparations. . mark that I do not confine myself to the use The advantages resulting from this improved of all the ingredients at the same time, when method of hardening and tempering are combined as described, as for some hardening First. The articles to be operated upon, in purposes a bath may be prepared of chloride stead of being exposed to the direct influence of sodium, in combination with any of the in of the products of combustion while being gredients named, or others possessing the same heated, as in the ordinary mode of operation, or similar properties in a state of igneous fu are immersed in the bath, and consequently sion; nor do I claim the use of the within protected from the air. They are therefore uni named Substances when the same are used in formly heated in all parts simultaneously and a state of aqueous solution; but are free from the injuries resulting from un What I claim is equal heating, which in the ordinary mode are The use of a bath of chloride of sodium, with unavoidable. or without ferrocyanide or bichromate of pot. Second. The temperature required to main ash, or either of them, or of other ingredients tain the bath in a state of igneous fusion may possessing similar chemical properties, com be varied according to the hardness required. bined with animal or vegetable charcoal and The articles to be operated upon, after remain ground bone, when the foregoing substances ing in the bath a sufficient time to acquire the are in a state of igneous fusion, combined and same temperature, must, when taken from the operating as herein set forth. bath and dipped into the water or oil, or other EORACE WAUGHN. solutions, become equally hard. In presence of - Third. When articles of steel are operated R. T. BIRCHETT, upon the process of “letting down?--that is to GEO. C. THOMAS,