Comment on “Effects of niobium addition on microstructure and tensile behavior of as-cast ductile iron” by Chen et al. [Mater. Sci. Eng. A 688 (2017) 416]

This letter attempts to comment on the article by Chen et al. [Mater. Sci. Eng. A 688 (2017) 416] in the aspects of microstructure and tensile properties of ductile iron with niobium additions.