Effect of cooling rate on the microstructure and mechanical properties of high Ti-V microalloyed steel

¹ Department of Material Science and Metallurgical Engineering, University of Pretoria, South Africa
² Advanced Material Division, Mintek, South Africa

Abstract

High-strength low-alloy steels are known for their superior mechanical properties and these desired properties are achieved through controlled hot rolling. The cooling rate is one of the most important factors in controlled hot rolling, which plays a major role in the final microstructure and mechanical properties. In this work, the effect of the cooling rate on the final microstructure and mechanical properties of high Ti-V HSLA microalloyed steel was investigated using the Gleeble 1500™ thermomechanical processing simulator. The samples were cooled to room temperature after final pass deformation using two different cooling rates to simulate the 16 and 30 mm thick plate rolling patterns. Polygonal ferrite was found to be a dominant phase in the final microstructures; SEM-EBSD IPF maps also showed grains with random orientation distribution. Yield strength and ultimate tensile stress increased by approximately 14% and 10%, respectively, with increasing cooling rate.