| 摘要 |
PROBLEM TO BE SOLVED: To provide automobile chassis parts enhanced in strength, toughness and corrosion resistance, and its manufacturing method. SOLUTION: The automobile chassis parts 1 manufactured from a specific component under specific conditions and having an arm part 2 of an approximately H shape in cross section, which comprises a peripheral rib 3 having a relatively narrow width and a central web 4 having a thin thickness of 10 mm or less and a relatively large width, is enhanced in strength, toughness and corrosion resistance, by specifying: the density of a crystallized product observed in a microstructure in a cross-sectional site (7), where the maximum stress occurs, in the cross section in the width direction at the maximum stress producing site in a rib (3a); the spacing between grain boundary precipitates observed in a microstructure at a cross-sectional site (8) including a parting line and the size and density of dispersed particles; the proportion of recrystallization observed in cross-sectional microstructures (7, 8) of the ribs; and the proportion of recrystallization observed in a cross-sectional microstructure (9) in the width direction of the web (4a) adjacent to the cross-sectional microstructure of the rib (3a). COPYRIGHT: (C)2008,JPO&INPIT
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