| 摘要 |
PROBLEM TO BE SOLVED: To provide vacuum-carburized parts having superior impact resistance, and to provide a method for manufacturing such vacuum-carburized parts. SOLUTION: The vacuum-carburized parts have a ratio (surface N amount/inner N amount) of an average nitrogen amount (surface N amount) in a region 50μm deep from the surface of the parts to an N amount inside the parts, in an amount of 0.8 or more; and has the superior impact resistance. When the region 50μm deep from the surface of the vacuum-carburized parts is observed with a magnification of 200 times by using an optical microscope, crystal grains with a grain size number of 4 or less occupy about less than 5% of an observed view by an area rate. COPYRIGHT: (C)2007,JPO&INPIT
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