Nippon Steel Corporation

Kiyoshi Yamaji

Toshio Tanoue

Masao Kikuchi

Akihiko Takahashi

Masayuki Tendo

Brake disc produced by a hot-rolled stainless steel excellent in resistance to temper softening, characterized in that: said steel contains, in terms of wt %, C: 0.01 to 0.1%, N: 0.03% or less, C&plus;N: 0.04 to 0.1%, Si: 1% or less, Mn: 20 or less, Ni: less than 0.5%, Cr: 10 to 15%, and Nb: 0.02% to 0.5%, with the balance Fe and unavoidable impurities; that the hardness after quenching heat treatment is in the range of 30 to 40 HRC; and that the temper softening temperature for lowering the hardness to below 30 HRC is at least 530&deg; C. Further, it is desirable to add at least one of the following elements; 0.1 to 2% of Cu, 0.1 to 1% of Mo, 0.01 to 0.5% of Ti, 0.01 to 0.5% of V or 0.0005 to 0.01% of B, and to make the value of &ggr; calculated from steel chemical composition at least 70%.

Stainless steel for brake disc excellent in resistance to temper softening

A brake disc capable of being used in an as quenched state, excellent in rusting resistance, toughness and resistance to softening resulting from heat generation caused by braking, and preferably useful as a brake disc for a two-wheeled vehicle, which is produced from a martensitic stainless steel comprising 0.02 to 0.10% of C, up to 0.03% of N, up to 0.05% of Si, 0.5 to 1.5% of Mn, up to 0.5% of Ni, 10 to 15% of Cr, 0.5 to 2.5% of Cu, up to 0.1% of Al and the balance substantially Fe and unavoidable impurities provided that the amount of C+N is from 0.05 to 0.1% and .gamma.p is at least 90, and a process for producing the same.

Growing community of inventors

Kitakyushu, Japan

Kiyoshi Yamaji