HIGH CLEANLINESS STEEL SUPERIOR IN FATIGUE STRENGTH OR COLD WORKABILITY

摘要

PROBLEM TO BE SOLVED: To improve the cold workability and fatigue characteristics of high cleanliness steel. SOLUTION: The high cleanliness steel includes total-Li of 0.020 to 20 ppm (by mass), or total-Li and Si so as to satisfy total-Li/Si (by mass ratio)=1×10-6to 1,000×10-6; and oxide-based inclusions with a longer diameter of 20μm or larger in an amount of, for example, 1.00 piece or less per 50 g of steel. The high cleanliness steel has a chemical composition normally comprising 1.2% or less C (hereafter by mass%), 0.1-4% Si, 0.1-2% Mn, 0.01% or less total-Al, 0.005% or less O, 0.1-20 ppm total-Mg (by mass) and 0.1-20 ppm total-Ca (by mass). COPYRIGHT: (C)2006,JPO&NCIPI