Microstructure and Precipitation Behavior of Nb, Ti Complex Microalloyed Steel Produced by Compact Strip Processing

• DOI: 10.2355/isijinternational.46.1345
• Publication Date: 2006-09-15T05:53:03Z
• Authors: Ruizhen Wang; C. I. Garcia; M. Hua; K. Cho; Hongtao Zhang; A. J. Deardo
• Keywords: Microalloyed steel; Precipitation hardening; Thermomechanical processing

A comprehensive microstructure analyses were conducted for CSP processed Nb, Ti microalloyed steel, especially focusing on the precipitation behavior of microalloying elements Nb and Ti. After coiling, steel exhibits mainly a ferrite microstructure. The average grain size is 5.3 μm. has transitional morphology from polygonal to non-polygonal characterized by moderate dislocation density 2.47E+10/cm2. high complex star-like or cruciform shaped precipitates exist in steel. They are Nb-rich around 150 nm. About 49% total tied up precipitates, thus remarkably reducing amount available austenite conditioning, transformation temperature control as small strengthening particles ferrite. main mechanisms found refinement strengthening. Of yield strength, they represent contributions 44% 24%, respectively. There very little It thought that precipitate prone form Ti-containing niobium produced compact strip processing.