Abstract: A process for heat treatment of a plastically moldable workpiece, by plastically molding the workpiece at a first temperature to form a shape, mechanically restraining the workpiece by means of form-fitting, bringing the workpiece to a second temperature and subjecting it at least partially to a heat treatment, and removing the workpiece, wherein mechanically restraining the workpiece by means of form-fitting is accomplished by embedding the workpiece in a densely packed pourable embedding material located in a container, wherein the embedding material is stressed. The invention also includes an apparatus for practicing the process.