Application of Nb-O Affinity in Clean Steel

Masana Imagumbai; Hiroyuki Kajioka; Hiroshi Takechi

doi:10.4028/www.scientific.net/MSF.500-501.559

Paper Titles

Influence of Composition and Processing Conditions on Mechanical Properties and Fish-Scale Resistance of Microalloyed Steels for Double-Face Vitreous Enamelling
p.527

Processing Low and Ultra-Low Carbon Bainitic Steels with Excellent Property Combinations
p.535

Thermomechanically Hot Rolled High and Ultra High Strength Steel Grades - Processing, Properties and Application
p.543

Development of Low Carbon Microalloyed Ultra High Strength Steels
p.551

Application of Nb-O Affinity in Clean Steel
p.559

Development of NbTiB Microalloyed HSLA Steels for High-Strength Heavy Plate
p.565

Development of Low Carbon Microalloyed Bainitic Steels for Structural Plate Applications
p.573

Influence of Severe Accumulative Rolling in a Low Carbon Microalloyed Steel
p.581

Development of Process Technology for Vanadium Containing, High-Strength, Low-Carbon, Heavy Plate and Its Trial Manufacture
p.589

HomeMaterials Science ForumMaterials Science Forum Vols. 500-501Application of Nb-O Affinity in Clean Steel

Application of Nb-O Affinity in Clean Steel

Abstract:

This report introduces a new deoxidation process that starts with a vacuum degassing followed by the addition of ferro-niobium in the same vacuum facility. The addition of strong deoxidation substance like aluminum and/or silicon is not adopted. Owing to the degassing in vacuum, which in reality reacts as deoxidation with C in molten steel, the solute oxygen in molten steel (O) is stabilized by niobium, which generates an ample number of fine oxide particles composed of (Nb, Mn)2O3-phase. Provided the carbon-degassing is conducted so as to reach the O prior to the FeNb addition would be around 100ppm and less, these oxide-inclusions do not agglomerate before and during solidification, because of the weak cohesivity of niobium-based oxides in molten steel, which would enable defect-free cast products as well as clogging-less casting operation. Also, the steel containing these fine (Nb, Mn)2O3-particles but no Al, exhibits so-called intra-granular acicular ferrite transformation and good toughness of weld heat affected zone (HAZ).