Gas nitriding process - carried out in presence of DC and AC magnetic fields (SE 14.2.83)

摘要

During workpiece heating in a gas nitriding process, at the moment of reacting the temp. corresp. to the start of dissociation of the nitriding medium with formation of active nitrogen, a d.c. magnetic field, intersected by an industrial frequency a.c. magnetic field, is created in the nitriding chamber. The field is maintained during the isothermal treatment and subsequent cooling until reacting the temp. corresp. to the transformation finish. The magnetic field allows the range of properties of the nitrided layer to be varied over a wider range so that alloy steels having reduced surface hardness (permitting a wider choice of friction couples and the possibility of plastic working) and low carbon steels having increased hardness and ductility can be produced.