US2152154A

US2152154A - Method of and apparatus for the heat treatment of metals and alloys

Info

Publication number: US2152154A
Application number: US60002A
Authority: US
Inventors: Robiette Alfred Gordon Evans
Original assignee: BIRMINGHAM ELECTR FURNACES Ltd
Current assignee: BIRMINGHAM ELECTR FURNACES Ltd; BIRMINGHAM ELECTRIC FURNACES Ltd
Priority date: 1935-01-19
Filing date: 1936-01-20
Publication date: 1939-03-28
Anticipated expiration: 1956-03-28

Description

March 28, 1939. A. ca. E. ROBI ETTE v 54 METHOD OF AND APPARATUS FOR THE HE AT TREATMENT OF METALS AND ,LOY Filed Jan. 20,1936

Patented Mar. 28, 1939.

METHOD OF AND APPARATUS FOR; THE HEAT 'JIREIATMEN'I 0F METALS AND ALLOYS Alfred Gordon Evans Robiette, Erdington, Birmingham, England, assignor to Birmingham Electric Furnaces Limited, ,Erdington, Birmingham, England, a British company Application January 20, 1936, Serial No. 60,002 In Great Britain January 19, 1935 2Claims.

(CI. 34-24) I (Granted under the provisions of sec. 14, act

- of March 2, 1927; 357 0. G. 5)

This invention has reference to the heat-treatment of metals and alloys, and particularly to the bright-annealing of brass and other alloys that contain a constituent metal whichvolatilizes at annealing temperature.

It is well.known that where articles made from such alloys are produced by rolling, drawing, pressing, or other methods that involve the use of oil or grease, it is not practically or economically possible to wholly remove the lubricant from the surfaces ofthe products before subjecting them toheat-treatment, with the consequence that when the lubricant is decomposed by the treatment heat, it deposits carbon on the products and causes surface discoloration. Similarly, where the lubricant contains moisture or other source of oxygen, such moisture or the like will be decomposed by the treatment heat and also set up surface discoloration.

The principal object of the present invention is to provide an annealing furnace which is adapted to perform a preliminary heating of the work in the treatment chamber to a temperaturewhich will dry off moisture and volatilize or vaporize oil or other lubricant, but is lower than the temperature at which the said work is susceptible to oxidization in the presence of moisture, and substantially lower than the annealing temperature at which the volatile metallic constituent of the alloy may volatilize.

According to the present invention, this process is carried out in an annealing furnace in which a fan is employed for circulating atmosphere-gas through the work container and through an externally-heated passage which surrounds the said container and-is adapted to be charged with an oxidizable medium, which medium becomes oxidized preferentially to the work under treatment.

On the attached sheet of drawing, forming a part of this specification, I have illustrated a vertical sectional view of a furnace constructed in accordance with my present invention.

The preferred form of furnace includes a fan or propeller a which will circulate the atmosphere or gas through 'the work, especially during the preliminary lubricant-removing treatment. It also embodies means whereby, during the preliminary heating, the gas-circulating passage may be vented, or placed in communication with the outsiderair, (as, for example, by the valve-controlled exhaust pipes c, c) to enable the discharge or exhaust of the volatillzed or vaporized substances, whereas during the annealing treatment, the said container may be closed, or substantially closed or be so controlled at the vents upon the exhaust vents may be closed, or substantially closed, to prevent or reduce the loss of at,- I

mosphere-gas during the subsequent annealing treatment.

is assisted by-the use of a body or charge of readily-oxidizable alloy (such as alloys of the same or similar constitution as the products or work to be annealed) which is in such a physical condition, and is so arranged with respect to the work-container and heaters of the furnace that it may readily be raised, in a given time, to a temperature higher than that of the work-charge. Such an oxidizable charge is shown in the drawing, marked 1, and is located and arranged in the gas circulating system so that it is enabled when heated to the appropriate temperature, to take up from the circulating gas, any oxidizing substance, and/or any vaporized lubricant that may be removed from the work-charge during the'annealing treatment.

Where, as in the furnace illustrated, the oxidizable charge is located in the gas passages outside the work-container it is heated by resistors e or the like contained in a chamber surrounding the said gas passages; the arrangement being such that when the furnace is in operation for annealing the work-charge, the oxidizable charge in the externally-heated gas passages is maintained at a temperature rather higher than that of the said work charge. This enables, the oxidizable medium to be quickly heated to its effective temperature before the work-charge is brought to annealing heat.

The oxidizable medium which becomes oxidized preferentially to the work'under treatment may consist of loosely-packed swarf or waste alloy in small pieces, or wire-mesh or the like, such as will not materially impede the circulation of gas through the system. The passages in and consisting of a metal or an alloy of metal of substantially the same constitution; as the metal or alloy of metal within the work-container. i

2. A process for the the cleaning and annealing of metals and alloys of metals comprising the step of treating said metals or alloys of metals with heated air which has been passed in contact with an oxidizable medium consisting of a metal oran alloy'of metal of substantiallythe same constitution as the metal or alloy of metal undergoing treatment.

ALFRED GORDON EVANS ROBIETTE.