Method of spray forming readily weldable and machinable...

Details Method of spray forming readily weldable and machinable... Method of spray forming readily weldable and machinable...

1998-11-04

2001-07-10

Bareford, Katherine A. (Department: 1762)

Metal founding

Process

Disposition of a gaseous or projected particulate molten...

C427S449000, C427S456000

Reexamination Certificate

active

06257309

ABSTRACT:

TECHNICAL FIELD
The present invention relates to the making of tools, and more particularly to a method of spray forming readily weldable metal deposits of low carbon steel.
BACKGROUND ART
Spray forming has become an accepted technique for producing steel prototype tooling (such as dies or molds) in a fraction of the time needed to make steel tooling conventionally. Spray forming techniques typically involve the following steps: (i) casting and solidifying a ceramic spraying pattern about a plastic master pattern of the tool to be produced; (ii) thermally spraying metallic particles onto a ceramic pattern; (iii) allowing the sprayed metallic particles to cool thereby forming a metal deposit having the general shape of the master pattern; and (iv) separating the metal deposit from the ceramic pattern.
The metallic particles being thermally sprayed onto the ceramic pattern typically consist of steel having a carbon content of about 0.8% by weight. The use of steel having a carbon content of about 0.8% by weight results in metal deposits which have good surface and structural characteristics. However, the deposits formed of carbon steel have a carbon content of about 0.4% to 0.8% by weight do not lend themselves to be easily weldable or machinable. Thus, when a tool (i.e., a die or mold) formed of a metal deposit made using steel having a carbon content of about 0.8% by weight cracks, or needs modifying to accommodate a design change, the tool is no longer useful and a brand new tool must be prepared since the tool is not easily weldable or machinable.
Accordingly, it would be desirable to provide a method of making a spray forming metal deposit which is readily weldable and machinable.
Accordingly, it is an object of the present invention to provide a readily weldable and machinable metal deposit and a method of making the same.
DISCLOSURE OF INVENTION
The invention meets the above object and others by providing a method of spray forming a readily weldable and machinable metal deposit. The method comprises (a) providing a ceramic spray forming pattern; (b) heating the spray forming pattern to a sustained temperature sufficient to inhibit internal stress formation in carbon steel having a carbon content of less than about 0.3 weight percent deposited on the heated spray forming pattern; (c) spraying metallic particles onto the spray forming pattern while the spray forming pattern is heated to the sustained temperature, the metallic particles having a carbon content which is sufficient to result in metal particles having a carbon content of less than about 0.3 weight percent when deposited on the heated spray forming pattern; and (d) allowing the sprayed metallic particles to cool to form a metal deposit having a carbon content of less than about 0.3 weight percent.


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Thermal Spraying: Practice, Theory, and Application, American Welding Society, p. 57 1985 (no month date).*
Hackh's Chemical Dictionary, Julius Grant, ed., McGraw-Hill Book Company, pp. 636-637, 1969 (no month date).

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