| 摘要 |
<p>A brake disk having proper hardness and high temper softening resistance is provided. In particular, the brake disk has a martensitic structure having prior-austenite grains with an average diameter of 8 µm or more, a hardness of 32 to 38 HRC, and high temper softening resistance. The brake disk contains, by mass, 0.1% or less of C, 1.0% or less of Si, 2.0% or less of Mn, 10.5% to 15.0% of Cr, 2.0% or less of Ni, greater than 0.5% to 4.0% of Cu, 0.02% to 0.3% of Nb, and 0.1% or less of N and further contains C, N, Nb, Cr, Si, Ni, Mn, Mo, and Cu, the remainder being Fe and unavoidable impurities, such that the following inequalities are satisfied: 5 �¢ Cr + 10 �¢ Si + 15 �¢ Mo + 30 �¢ Nb - 9 �¢ Ni - 5 �¢ Mn - 3 �¢ Cu - 225 �¢ N - 270 < 45 0.03 ‰¤ { C + N - ( 13 / 93 ) Nb } ‰¤ 0.09</p> |
