PURPOSE: To provide a corrosion resisting thread guide control guide possessing both excellent corrosion resistance and surface hardness by forming a specified nitriding hardened steel layer on the surface layer of austenitic stainless steel.
CONSTITUTION: A thread guide control guide which is ring-shaped and has a central hole 1 for passing through a tread 2, or a roller-shaped control guide rotating followingly to the running of the thread 2 is formed by using austenitic stainless steel as base material, and generating a nitriding hardened layer which does not substantially contain crystal chrome nitride and contains 2 to 12 weight % of N-atom in the structure of the top nitriding hardened layer on at least the part of the surface layer. The nitriding hardened layer is formed by carrying out the fluoride-process of a formed product in the temperature domain lower as much as 100 to 200°C than ordinary nitriding temperature. Thus the N-atom penetrates into the base material without depositing crystal chrome nitride, and when the content of the N-atom is controlled within the range of 2 to 12%, the nitriding hardened layer having high surface hardness can be formed without the deterioration of corrosion resistance.
KITANO KENZO
HAYASHIDA TADASHI
MINATO TERUO
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