| 摘要 |
PROBLEM TO BE SOLVED: To provide a metal ball for a rolling motion object, wherein the uniformity of a solidified structure is high, coarse shrinkage cavities are not generated, and variation in the hardness inside the metal ball is reduced. SOLUTION: Disclosed is the metal ball for a rolling motion object obtained by spherically solidifying an alloy having a composition containing, by mass, 4.0 to 6.0% Si, 2.5 to 3.0% B and 0.1 to 0.6% C, and the balance Fe with inevitable impurities, wherein ≥80% of the structure is composed of a composite structure of α-Fe dendrite crystals with the second interarm distance of ≤5 μm and an Fe-B compound, and a hardness is ≥700 HV. Further, the metal ball for the rolling motion object preferably contains, by mass, 0.1 to 2% Mo. COPYRIGHT: (C)2009,JPO&INPIT |
