| 摘要 |
PROBLEM TO BE SOLVED: To provide a spring steel for obtaining a spring superior in fatigue properties by suppressing the production of hard crystals, and to provide a spring superior in fatigue properties which is obtainable from such spring steel. SOLUTION: The spring steel satisfies a chemical componential composition, contains oxide inclusions satisfying the following conditions (1) to (3) in a number of 1×10<SP>-4</SP>or more per square millimeter: (1) the oxide inclusions each contain a total of 80% by mass or more of Al<SB>2</SB>O<SB>3</SB>and SiO<SB>2</SB>based on 100% by mass of the inclusion composition excluding Li<SB>2</SB>O, (2) the oxide inclusions each have a ratio by mass of Al<SB>2</SB>O<SB>3</SB>to SiO<SB>2</SB>of from 1:4 to 2:3; and (3) the oxide inclusions each contain Li, and further contains Mg-containing oxide inclusions satisfying the following conditions (4) to (6) in a number of 1×10<SP>-4</SP>/mm<SP>2</SP>or more per square millimeter: (4) the Mg-containing oxide inclusions each contain a total of 80% by mass or more of MgO and SiO<SB>2</SB>based on 100% by mass of the Mg-containing oxide inclusion composition; (5) the Mg-containing oxide inclusions each have an MgO content (% by mass) larger than an SiO<SB>2</SB>content (% by mass); and (6) the Mg-containing oxide inclusions each have an SiO<SB>2</SB>content of more than 25% by mass. COPYRIGHT: (C)2010,JPO&INPIT |
