Method and apparatus for additive manufacturing under protective gas

A method of additive manufacture of a workpiece in a manufacturing chamber under protective gas, in which a workpiece is assembled from a sequence of workpiece outlines that are each manufactured by melting a metallic material in powder or wire form by contacting with an energy beam, where the workpiece outlines are manufactured under the action of a protective gas with a composition that varies during the manufacture of the workpiece;

• wherein zones of different metallurgical properties are created within the workpiece by using, as protective gas in the manufacture of each workpiece outline, a gas mixture consisting of an inert gas and carbon dioxide, the composition of which is determined in each case depending on defined metallurgical properties of the respective workpiece outline, and which is supplied in this composition before and/or during the manufacture of the workpiece outline;
• and
• wherein the workpiece outline is subjected to a heat treatment during and/or after manufacture, the heat treatment comprising heating the protective gas using a heating device in a protective gas supply line that provides the protective gas to the manufacturing chamber.