A study on Nb-V microalloyed steel for 460 MPa grade H-section columns

• Published in: Journal of constructional steel research Vol. 170; p. 106112
• Main Authors: Koo, Bon Seung, Lee, Chul Won, Lim, Young Hoon
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.07.2020
• Subjects: Flow stress; Niobium; Non-recrystallization; Precipitation hardening; Vanadium; Non-recrystallization; Precipitation hardening; Niobium; Vanadium; Flow stress
• ISSN: 0143-974X; 1873-5983
• DOI: 10.1016/j.jcsr.2020.106112

Modern trends in high-rise constructions are the use of high-strength hot-rolled section steels with improved impact toughness. The use of higher strength enables architects to use thinner sections and allows achieving a considerable reduction in the total cost of materials. Following the trends, the development of low-carbon steel with a minimum yield strength of 460 MPa has been studied. Alloying elements and process operating conditions were selected to increase strength, elongation, and toughness simultaneously. Two alloying elements, niobium and vanadium, were chosen to enhance strength and impact toughness. Thickness reduction per pass was controlled to perform excessive deformation below the austenite recrystallization stop temperature, and then accelerated cooling has proceeded to obtain grain refinement. Flow stress analysis and microstructure observation have been conducted to cross-validate the effect of precipitation hardening, along with material testing for the evaluation of the mechanical properties. •Development of 460 MPa grade H-shaped beams.•Niobium and vanadium addition on low carbon steel for mechanical property enhancement.•Strain-induced precipitation hardening of niobium with grain refinement mechanism below TNR.•Cooling-induced precipitation hardening of vanadium.