MIDDLE AND HIGH CARBON STEEL SHEET WITH HIGH-STRENGTH SUPERIOR IN STAMPABILITY

摘要

PROBLEM TO BE SOLVED: To provide a middle and high carbon steel sheet with high-strength which has high strength and superior stampability and is suitable for parts for various machine structures.;SOLUTION: The middle and high carbon steel sheet with high-strength has a metallurgical structure in which carbides with an average particle diameter of 0.30 μm or smaller are dispersed in a matrix consisting of ferritic crystal grains with an average grain size of 2.0 μm or smaller; contains C in an amount of 0.30 to 1.00 mass%; and is thermally refined into the hardness of 250 HV. Specifically, the steel sheet has a composition comprising 2.0 mass% Si or less, 1.0 mass% Mn or less, 0.03 mass% P or less, 0.02 mass% S or less, 0.1 mass% acid-soluble Al or less in addition to 0.30-1.00 mass% C, and the balance substantially Fe; and may also further include one or more elements of 2.0 mass% Cr or less, 0.5 mass% Mo or less, 0.3 mass% Cu or less, 2.0 mass% Ni or less and 0.10 mass% Ti or less.;COPYRIGHT: (C)2007,JPO&INPIT