| 摘要 |
PROBLEM TO BE SOLVED: To establish a technology for balancing high strength with high toughness at a high level. SOLUTION: A hypereuctectoid steel includes 0.9-1.50% C (by mass%, hereinafter the same about an amount of elements), 1.0% or less Si, 2.0% or less Mn, and 0.05-2% Cr; and has a composite structure contaning cementite and ferrite. In the structure, spheroidal cementites with aspect ratios of 1.5 or less occupy 90 area% or more of all cementites, and exsist in a range of 1.0×10<SP>11</SP>to 100×10<SP>11</SP>particles/mm<SP>2</SP>. The ferrite has an average particle diameter of 0.5μm or larger but smaller than 2μm, when measured with a section method in the vicinity of a grain boundary having a difference between orientations of 15 degrees or more. COPYRIGHT: (C)2005,JPO&NCIPI
|
