United Technologies Corporation

Edward M Breinan

Bernard H Kear

Conrad M Banas

Anthony F Giamei

Clyde O Brown

A method is described for the production of bulk rapidly solidified metallic articles of near-net shape, by depositing multiple thin layers of feedstock using an energy beam to fuse each layer onto a substrate. The feedstock may be in the form of metal powder or wire. Different finished geometries are also described.

Method for fabricating articles by sequential layer deposition

A surface treatment for a class of metallic articles is described. The treatment involves the melting of a thin surface layer of the article by a concentrated energy source, within a narrow set of parameters. The melting step is performed in a manner which maximizes the temperature gradient between the melted and unmelted portion of the article, consequently, cooling and solidification upon the removal of the energy source is extremely rapid and can produce unique microstructures. The preferred energy source is a continuous wave laser, and in the preferred embodiment, a flowing inert gas cover is used to minimize melt contamination and plasma formation. The technique may be used to produce amorphous surface layers in a specific class of eutectic alloys. In another class of alloys, based on the transition metals and containing precipitates rich in one or more metalloids, uniquely fine microstructures may be produced.

Skin melting

A method of accomplishing a controlled weld with a beam of laser radiation is disclosed. The workpiece is cleaned and fitted prior to joining and a flow of a gas is provided in the weld region to prevent the formation of radiation insulating plasma between the laser source and the workpiece and to aspirate gaseous impurities from the weld zone. In addition, a trailing cover gas is provided to both the top and the bottom of the weld until the joint is sufficiently cooled to prevent reaction between the metal and the atmosphere. The beam must contain more than two kilowatts of power and be focusable on the workpiece to a power density of at least one megawatt per square inch in order to produce a keyhole in the fusion zone. Further, a weld speed in excess of twenty inches per minute and a progressive solidification technique of the weld contribute to the expulsion of contaminants from the weld.

Growing community of inventors

Glastonbury, CT, United States of America

Edward M Breinan