US669925A - Process of toughening manganese steel. - Google Patents

Description

Patented Mafr. l2, 190|.l H. u; HlBBAo. PROCESS 0F TOUGHENING MANGANESE STEEL.

(Application tiled Aug. 6, 1897.)

IN VENTR Heummi KRD-- um @Y ATTORNEYS.

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HENRY D. I-IIBBARD, OF NORTH PLAINFIELD, NEW JERSEY.

PROCESS OF TOUGHENING MANGANESE STEEL.

SPECIFICATION forming part of Letters Patent No. 669,925, dated March 12, 1901.

Application led August 6, 1897. Serial No. 647,312. (N0 Specimens.)

To all whom, it may concern;

Be it known that I, HENRY D. HIBBARD, a citizen of the United States of America,.re siding in North Plainfield, Somerset county, New Jersey, have invented certain Improvements in Toughening Manganese Steel, of which the following is a specification.

My invent-ion consists of certain improvements in toughening castings or other articles of manganese steel, fully described hereinafter.

In order to give manganese-steel articles the best physical properties, it is essential that such articles be heated to a high degree and then quickly cooled in a bath. If such articles have a considerable thickness-say over one inch-they are liable to be injured or rendered defective by internal ruptures if they are heated quickly. Such internal rupture is due to strains caused by rapid, and

therefore irregular, heating, and is especiallyV marked in manganese steel, because of its low heat-conducting power. A method heretofore adopted of overcoming these difficulties has been to charge the manganesesteel articles into a cold furnace, which is then fired slowly up to the proper degree of heat,w"here upon the articles are withdrawn and quickly plunged into a cooling-bath. This method carries with it the objection that it is wasteful of fuel. It allows a given furnace to give but a small output, and especially when work is pressing the furnace is apt not to be allowed to cool off sufficiently before a new charge is put in, and the castings or other articles of the new charge are liable to be dam aged accordingly. j

The objects of my invention are to avoid these objections, to provide a mode of working which will permit of a continuous operation of the furnace or furnaces, increase the output accordingly, save fuel, and yet insure that gradual heating which is essential to the proper treatment of manganese steel. I attain these objects by the mode of operation which I` will now describe.

I provide a long furnace (or two furnaces in series may be employed) with a horizontal or slightly-inclined hearth and with the fireplace or other heating means so arranged that one end can be heated to the highest temordinary atmospheric temperature.

perature required for the process, while the temperature of the heating chamber or chambers will be gradually less as the other end of the furnace or furnaces is approached. At this cool end the temperature should be near By this means I establish in the heatingfurnace a series of what may be termed consecutive heating zones,having temperatures increasing gradually from a low predetermined ternperature which will not injure the articles up to a high heat, and the temperature of each zone is maintained at a practically7 uniform degree.

The articles to be treated are introduced or charged at or near the cool end of the furnace or furnaces and are slowly transferred toward the hot end by rolling, if of suitable shape, or by pushing or sliding or by transfer from door to door or by equivalent means. When at the hot end of the furnace or furnaces the articles have reached the desired temperature, they are withdrawn and quickly plunged into a cooling-bath to complete the toughening operation.

I do not confine myself to any special construction of furnace or furnaces for carrying out my invention; but in the accompanying drawingsI have illustrated one construction of furnace which may be used.

Figure l is a side elevation. Fig. 2 is a transverse vertical section on the line 2 2, Fig. l; and Fig. 3 is a sectional plan on the line 3 3, Figs. l and 2.

A' is the long heating-chamber, having opposite ends ot a', closed by doors, and at the sides a series of openings a2 CL3, of suitable size, closed by doors. At one end is the iireplace or other source of heat F, and at the same end, but on the opposite side of the furnace, is the chimney or outlet-flue C. This end of the heating-chamber is to be heated to the highest temperature required for the operation, while the opposite end of the chamber will be comparatively cool. Sliding partitions P may be employed to aid in regulating the temperature in diiferent parts of the chamber. The manganese-steel articles are introduced through the doorway a and as required are moved forward successively t0- Ward the hot end of the furnace by any suit- IOO able means. Thus if the articles are cylindrical or of other shapes suitable for rolling they may be rolled forward toward vthe hot end from time to time by means of ba-rs or other instruments introduced through the holes a2 a2.

If the articles are not thick, the operation may be shortened by introducing them into the furnace at a point between the coldest and hottest ends, as through one of the doorways a3, where the degree of heat is as great as experience has shown can be endured by the article without injury. When heated to the required heat-say 1,700o Fahrenheitat the hot end of the furnace, they are Withdrawn through the door a and plunged quickly into a cooling-bath.

It will be observed that a characteristic feature of my heating-furnace is that there is a long part of the chamber through which the Iiames or products of combustion do not sweep on their way to the outlet or chimney, but through which the articles are fed toward the flames or products of combustion, the heatin which portion of said chamber being that due to radiation from the flames or products of com bustiou and the walls of the furnace, such heat gradually diminishing in temperature in proportion to the distance from the furnace end of the chamber.

I claim as my invention- The mode herein described of toughe'ning manganese-steel articles, said mode consisting in first, establishing, in a heating apparatus, a series of consecutive heating zones having temperatures increasing gradually from a 10W predetermined temperature which will notinjure the articles to a high heat and maintaining the temperature of each zone at a substantially uniform degree, then introducing the articles successively into the zone of lowest temperature and moving them through the consecutive zones so as to subject them to a gradually-increasing temperature, preventing the products of combustion from coming into contact with the articles iu the zones of lower temperature and permitting said articles to come into contact with the said products of combustion during their passage through the hottest Zone, and finally withdrawing said articles from the hottestzone, and plunging them into a cooling-bath, substantially as described.

In testimony whereof 1 have signed my name to this specification in the presence of two subscribingwitnesses.

HENRY D. HIBBARD.

Witnesses:

ALLAN K. ALEXANDER, HUBERT HowsoN.

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