US 4,234,776 AGranted

Method of producing areas of alloy metal on a metal part using electric currents

AssigneeThermatool Corp.

InventorsWallace C. Rudd, Humfrey N. Udall

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Abstract

A method and apparatus for modifying the surface properties of a metal part in which electric current having a frequency of at least 3000 Hz is supplied to a narrow area on the part by means of contacts, one at each end of the area, and a proximity conductor or is induced therein by an induction coil until the metal in the area reaches a temperature at least equal to its melting temperature. A material which will alloy with the metal of the part is added to the molten metal so that when the molten metal is cooled an area of an alloy of the metal and the added material is produced. The added material may be in the form of a gas, powder, salt, wire, rod, bar, foil, etc. and may be applied to the area before, during, or after the melting of the metal of the area. The spacing between the proximity conductor or the induction coil and the work is no greater than three times the width of the proximity conductor or the coil conductor.

Claims27

Dependent claims

A method for producing in an area on the surface of a metal part, a volume of metal which is the fusion product of the metal of said part and an alloying material which forms an alloy with, and has a composition different from, the metal of said part, said fusion product having a composition different from that of the metal of said part and said volume of metal being structurally continuous, said method comprising:

heating the metal in said area of said surface to at least its melting temperature without heating adjacent metal to its melting temperature thereby to provide a pool of molten metal of said part extending inwardly from said surface and to be mixed with said alloying material, said heating being performed by causing an electric current having a frequency of at least 3000 Hz to flow in said area while causing a current of the same frequency to flow in a conductor overlying said area but which, at any instant, flows oppositely to the direction of the current flow in said area, said conductor being spaced from said area by a distance not greater than three times the width of said conductor, said current being caused to flow in said area by contacting said part with contacts respectively contacting the surface of the metal part at opposite ends of said area and connected to a source of said current, at least one of said contacts being connected to said source in series with said conductor;
depositing said alloying material on said area before, during or after heating of the metal of said area and heating said alloying material unit at least a portion thereof melts and the alloying material mixes with the molten metal of said part and the metal of said area is structurally continuous;
and
cooling the metal of said area to form a volume of metal in said area at the surface of said metal part which extends inwardly from said surface, which comprises an alloy of the metal of said part and of said alloying material formed in situ and which is structurally continuous.

1 more element

A method for producing spaced lengths of metal at an area on the surface of a metal part said lengths of metal being the fusion product of the metal of said part and an alloying material which forms an alloy with, and has a composition different from, the metal of said part, said fusion product having a composition different from that of the metal of said part and said lengths of metal being structurally continuous, said method comprising:

contacting said metal part with a first contact means at one end of said area and with a second contact means at the opposite end of said area thereby to define the length of said area;
rapidly heating spaced lengths of the metal of said area at least to the melting temperature thereof without heating metal intermediate said lengths to said temperature by varying the heating along the length of said area, said heating being produced by supplying electric current having a frequency of at least 3000 Hz to said contact means, and hence, to said metal part, through proximity conductor means which overlies substantially the length of said area between said contacts, which is spaced from the surface of said area by not more than three times the width of said proximity conductor means in the direction substantially parallel to the surface of said area and perpendicular to said length of said area and which is connected to said contact means so that the current therein, at any instant, flows oppositely to the flow of current in said metal part and by varying the heating along the length of said area;
depositing said alloying material on the spaced lengths of metal of said area before, during or after the metal thereof is heated and heating the alloying material until at least a portion thereof melts and mixes with the molten metal of said part and the metal of said lengths of metal is structurally continuous;
and
cooling the lengths of metal to form a plurality of said spaced lengths of metal at the surface of said metal part each of which comprises an alloy of the metal of said part and of said alloying material and which is structurally continuous.

2 more elements

A method for producing in an area on the surface of a metal part a volume of metal which is the fusion product of the metal of said part and an alloying material which forms an alloy with, and has a composition different from, the metal of said part, said fusion product having a composition different from that of the metal of said part and said volume of metal being structurally continuous, said method comprising:

contacting said metal part with a first contact means at one end of said area and with a second contact means at the opposite end of said area thereby to define the length of said area;
rapidly heating the metal of said area at least to the melting temperature thereof thereby to provide a pool of molten metal of said part extending inwardly from said surface and to be mixed with said alloying material, said heating being performed by supplying electric current having a frequency of at least 3000 Hz to said contact means, and hence, to said metal part, through relatively long and narrow proximity conductor means which overlies substantially the length of said area between said contacts, which is spaced from the surface of said area by not more than three times the width of said proximity conductor means in the direction substantially parallel to the surface of said area and perpendicular to said length of said area and which is connected to said contact means so that the current therein, at any instant, flows oppositely to the flow of current in said metal part;
depositing said alloying material on said area before, during or after heating of the metal of said area and heating said alloying material until at least a portion thereof melts and the alloying material mixes with the molten metal of said part and the metal of said area is structurally continuous;
and
cooling the metal of said area to form a volume of metal in said area at the surface of said metal part which extends inwardly of said surface, which comprises an alloy of the metal of said part and of said alloying material formed in situ and which is structurally continuous.

2 more elements

Dependencies are inferred from the claim text.