Specialized metallurgical processes – compositions for use therei – Processes – Producing or treating free metal
Reexamination Certificate
2004-12-17
2009-10-27
King, Roy (Department: 1793)
Specialized metallurgical processes, compositions for use therei
Processes
Producing or treating free metal
C148S320000
Reexamination Certificate
active
07608130
ABSTRACT:
The present invention relates to a high-cleanliness steel having a high fatigue strength and high cold workability, and a method of making the high-cleanliness steel. The method adds a Li—Si alloy having a Li content between 20 and 40% and/or Li2CO3as a Li-containing substance to a molten steel. The Li-containing substance is added to the molten steel after the completion of a series of steps of a ladle refining process including composition adjustment, temperature adjustment and slag refining. The high-cleanliness steel has a total-Li content between 0.020 and 20 ppm by mass and contains 1.0 or below oxide inclusion particle having a major diameter of 20 μm or above at a maximum in 50 g of the steel wire. The steel contains an oxide inclusion that has a CaO content between 15 and 55%, SiO2content between 20 and 70%, an Al2O3content of 35% or below, a MgO content of 20% or below and a Li2O content between 0.5 and 20%. The high-cleanliness steel has improved fatigue characteristics and improved cold workability.
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Fukuzaki Yoshio
Sakamoto Koichi
Suda Sumie
Sugimura Tomoko
Yoshida Atsuhiko
Kabushiki Kaisha Kobe Seiko Sho (Kobe Steel Ltd).
King Roy
Oblon, Spivak, McClelland, Maier & Neustadt, LLP
Shevin Mark L
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