| 摘要 |
PROBLEM TO BE SOLVED: To provide inexpensive machine structural components having excellent surface pressure resistance and bending fatigue strength. SOLUTION: A fine carbide dispersed carburizing layer is formed to≥0.15 mm by a gas carbonitriding heat treatment using steel of 0.85 to 1.25% in the content of Cr and 0.15 of 0.30 in the content of Mo as material and the strength is intensified by incorporating 25 to 45% residual austenite therein by nitrogen permeation. Further, an unintensified front layer 1 in which carbides hardly exist in the upper layer portion of a fine carbide dispersed carburization layer 2 and a surface defective section in which grain boundary oxidation exists are intended. The strength of a surface compressive residual stress≥1,000 N/mm<SP>2</SP>and surface hardness≥900 Hv is assured in the state of holding surface roughness at Ry≤3μm by micro-shot peening using shot grains of a grain size≤0.1 mm in diameter. Also, a sulfurizing layer is previously laminated on the surface of the front layer 1 by subjecting the front layer 1 to an electrolytic sulfurizing treatment. COPYRIGHT: (C)2005,JPO&NCIPI
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