Microstructural Control and DWTT Toughness in Thick-Walled Nb-Ti-V Microalloyed Linepipe Steels
Production of thick-walled low C Nb-Ti-V microalloyed linepipe steel has recently commenced in South Africa. Generally, the DWTT failures occurred when the average ferrite grain size was larger than 5µm and the pearlite colonies were coarse. This work examined the hot strip rolling behaviour of Nb-Ti-V microalloyed steel and quantified the most important parameters influencing final grain size and, hence, toughness. A Gleeble 1500 was used to both simulate hot rolling of relatively thick strip and also determine the no-recrystallisation temperature. For a fixed composition, final grain size was mainly controlled by the amount of strain applied below the norecrystallisation temperature, which was determined by the roughing mill exit temperature.
J.M. Rodriguez-Ibabe, I. Gutiérrez, B. López and A. Iza-Mendia
K.M. Banks "Microstructural Control and DWTT Toughness in Thick-Walled Nb-Ti-V Microalloyed Linepipe Steels ", Materials Science Forum, Vols. 500-501, pp. 303-310, 2005