Patent ID: 6464803
Filing Date: 2002-10-15
Classification: C21D,C22C

Abstract:
Brake disc excellent in resistance to temper softening, characterized in that: said brake disc is a hot-rolled stainless steel sheet quenched to a martensitic stainless steel sheet and said steel consists essentially of in terms of wt %,C: 0.01 to 0.1%, N: 0.014 to 0.03%, C+N: 0.04 to 0.1%, Si: 1% or less, Mn: 2% 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; wherein the hardness after quenching heat treatment is in the range of 30 to 40 HRC; and the temper softening temperature for lowering the hardness to below 30 HRC is at least 530Â° C.; andwherein a value of &ggr;p calculated from steel chemical ion as expressed below is at least 80%; &ggr;p=420Ã—[% C]+470Ã—[% N]+23Ã—[% Ni]+9Ã—[% Cu]+7Ã—[% Mn]âˆ’11.5Ã—[% Cr]âˆ’11.5Ã—[% Si]âˆ’12Ã—[% Mo]âˆ’47Ã—[% Nb]âˆ’52Ã—[% Al ]âˆ’49Ã—[% Ti]âˆ’23Ã—[% V]âˆ’500Ã—[% B]+189.