Abstract: The furnace effects a partial heat-treatment of drills and similar tools having a clamping portion and a working portion and with respect to which it is important to subjecting only the working portion, to a heat treatment, particularly hardening. The physical properties of the clamping portion are, retained essentially in their original state during the heat treatment. The furnace is provided with a tool receiver that cooperates with hearth-bottom plates that are traversed by cooling fluid. The tool receiver assures that the drills or other similar tools are maintained in their clamping portion at substantially the same temperature level during the heat treatment while the working portion of the tools is freely exposed to the heating and quenching.

Abstract: A method for gas carburization of workpieces made of steel in a furnace chamber, by which in the initial phase of the treatment more carbon than desired is released or dissolved in the workpiece surface and in the final phase of the treatment is decarburized to the desired edge carbon content by change of the quantity flow of the decarburizing gas. The decarburizing process is performed by exclusive introduction of a hydrogen-free, oxygen-containing decarburization gas in the furnace chamber.