Influence of cerium on the microstructure and mechanical properties of an as-cast and Q&T steel

摘要

In the present work the influence of Cerium on the microstructure and the mechanical properties of a cast, quenched and tempered GS33NiCrMo744 steel is analysed. The study shows that the addition of cerium to the steel melt results in an increase of the number of CeS dispersoids with a size between 0.5 and 3.0 mu m. The CeS dispersoids change the solidification morphology and the as-cast microstructure because as a nucleating agent for ferrite. Furthermore, a part of the cerium remains dissolved in the steel. The width of the columnar zone in 25 mm thick castings diametrically correlates with the amount of cerium. Furthermore, the secondary dendritic arm spacing (SDAS) has a tendency to decrease. The tensile strength of these cerium treated and then quenched and tempered (Q&T) steels increases with the number of cerium-containing dispersoids. However, samples with a wall thickness of 75 mm do not show this behaviour.