Properties and experiences rolling high Nb steels on Corus Plate Mills

Corus Plate Mills rolled a number of casts of High Nb steel (~0.05% C, ~0.09% Nb) from late 2004 to early 2006, primarily to assess the viability of achieving 25mm X65 with –22°C Battelles. To investigate the potential of these steels, various rolling schedules were applied and to further explore the possibilities a range of other gauges from 15mm to 50mm were also produced. This paper explores some of the properties obtained and how these were affected by the rolling schedules. Whilst the original objective was not achieved, some excellent strength and toughness combinations in 20mm plate were produced. Additionally, some higher temperature rolling schedules with relatively low post-hold reduction ratios were found to give good Battelles. The importance of adequate reheating to ensure that Nb precipitates are fully dissolved prior to rolling was also demonstrated. (AU)