Effect of rare earth metals on the structure and properties of structural steel

Abstract

1. The addition of rare earth metals to 40KhNMA steel increases the impact strength of transverse and longitudinal samples. The increase of the impact strength of transverse samples of 40KhNMA steel for a given technique of introducing rare earth metals is determined by the change in the type and shape of nonmetallic inclusions. 2. The addition of rare earth metals decreases the surface tension of the grain boundaries of structural steel, and this increases the impact strength. 3. The addition of rare earth metals to the ingot or to the ladle slows down the rare of growth of austenite grains; this is related to the amount, the shape, and the type of inclusions. 4. The rare earth metals decrease the hardenability of the steel, and this is the consequence of the decrease of the grain size and the increased contamination of the material with nonmetallic inclusions.