Microstructure and Tensile Properties of Graphite Ductile Iron Improved by Minor Amount of Dual‐Phased TiC–TiB2 Nanoparticles

Abstract

Herein, the effects of dual‐phased TiC–TiB2 nanoparticles on the microstructure and tensile properties of graphite ductile irons are investigated. Aluminum master alloys containing the TiC–TiB2 nanoparticles are utilized in the production of novel graphite ductile irons. It is found that the graphite nodules become finer with increased nodularity, smaller average diameter, and incremental amount per unit area. The thickness of ferritic and cementite layers in pearlite is reduced and the orientation becomes more regular. More ferrite is produced in the matrix after adding the nanoparticles. In tensile tests, the yield strength, tensile strength, and ductility are simultaneously improved. Also, it is determined that the cleavage and semicleavage fractures are transformed into ductile fractures after engaging the nanoparticles, which could be associated with more dimples and ductile risers being formed to promote the plastic deformation of the graphite ductile irons.