Research Specifications

The HSLA-100 steel is a family of thermomechanically processed Cu-bearing HSLA steels which was developed in the mid-1980s. This steel with higher strength, improved toughness and excellent weldability is used in the construction of hulls for naval warships and submarines and also for engineering bodies such as offshore drilling platforms, heavy duty trucks, bridges, ships, submarine hulls, naval vessels, and bodies, etc., replacing the conventionally used high yield series of steels.1,2 The mechanical properties of thermomechanically processed products, e.g. hot-rolled steel plates, are inferior in short transverse direction of steel plate than that of others.3–7 Hence, the examination of short transverse properties of steel plates, especially those that are used in large welded constructions, possesses of great necessity and importance. The characteristic of exhibiting different mechanical properties with respect to the direction of steel plate is referred to as mechanical anisotropy. Inferior short transverse mechanical properties of steels arise from four factors: (1) banded microstructures, (2) elongated inclusions, (3) crystallographic texture (preferred crystal orientation) and (4) elongated grains. It is well established, through several publications,3,8–12 that the elongated inclusions are the major contributors to mechanical anisotropy in steels. To diminish the anisotropy, changing the material composition chemistry (decreasing the sulphur content) and also changing the shape of inclusions from elongated to more globular (for example with calcium-treating techniques) are strongly recommended.8,13–17 Over the last few decades, a considerable number of investigations have been carried out on the HSLA-100 steel.18–29 However, despite the importance of short transversal properties of plates in large-scale welded constructions,3,30,31 the anisotropy of HSLA-100 steel has not been explored yet. The purpose of this paper is to present results from a study of the