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AssigneesWilkinson Sword Limited, Hitachi Metals, Ltd.
InventorsWolfgang Althaus, Atsushi Kumagai
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Steel which is particularly useful for making a razor blade of high corrosion resistance contains more than 0.45%, but less than 0.55%, of carbon, 0.4 to 1.0% of silicon, 0.5 to 1.0% of manganese, 12 to 14% of chromium and 1.0 to 1.6% of molybdenum all by weight, in addition to iron and inevitable impurities, and has a carbide density of 100 to 150 particles per 100 square microns as annealed. The razor blade has a Vickers hardness of at least 620 and a carbide density of 10 to 45 particles per 100 square microns, and preferably has a specific distribution of residual austenite content. The improved properties of the razor blade are achieved by an improved process of heat treatment which includes austenitizing the steel at a temperature of 1075.degree. C. to 1120.degree. C., cooling it to a temperature between -60.degree. C. and -80.degree. C. for hardening it, and tempering it at a temperature of 250.degree. C. to 400.degree. C.
A razor blade of high corrosion resistance made of steel consisting essentially of more than 0.45% and less than 0.55% by weight carbon, 0.4 to 1.0% by weight silicon, 0.5 to 1.0% by weight manganese, 12 to 14% by weight chromium, and 1.0 to 1.6% by weight molybdenum, with the balance being iron and inevitable impurities, said blade having a Vickers hardness of at least 620 and a carbide density of 10 to 45 particles per 100 square microns in a finished razor blade, said steel having a residual austenite content that gradually decreases from a surface of said blade, ranging from 24 to 32% at said surface, and from 6 to 14% at a depth of 50 microns below said surface.
Dependencies are inferred from the claim text.