The Role of Non-metallic Inclusions in stimulating the Intragranular Ferrite (IGF) Nucleation in Heavy Steel Sections

摘要

The use of non-metallic inclusions as intragranular ferrite (IGF) nucleation sites is a well identified method to refine steel microstructure in the heat affected zone (HAZ) of weldments. Recently, the implementation of the IGF nucleation mechanism in refining the final ferrite microstructure has received great attention, especially when the conventional refinement mechanisms are not feasible. In this study, the effect of MnS and Ti-oxide particles were used to promote IGF in a typical ASTM A572 grade 50 steel. This work included the study of the decomposition behavior of coarse grained austenite during very slow cooling rates in the presence of different types of non-metallic inclusions. Additionally, the effect of particles' type and size in stimulating IGF nucleation were identified.