1,214,406. Nitriding. H.J. FUCHS. May 15, 1968 [May 17, 1967], No.23164/68. Heading C7U. A workpiece which has been subjected to a nitriding process is, immediately after the nitriding and without further treatment, allowed to cool under vacuum at a pressure not exceeding 20 torr. The workpiece may be transferred from the salt bath or other nitriding furnace to a vacuum vessel which is then sealed and evacuated to the desired, pressure, e.g. 2 torr. Application of the invention to nitrided chrome-nickel steel sinter bodies and to chrome steel and stainless steel tools is described.
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