Titanium in the Rapidly Cooled Hypereutectic Gray Iron

Characterization of a Historical Cannonball from the Fortress of San Juan De Ulúa Exposed to a Marine Environment

“…Finally, another important feature of the microstructure to be addressed is the composition of titanium. It is well known that titanium is normally present in cast iron as a trace element coming from pig iron or steel scraps (Zeng et al ), usually in a composition range from 0.06 to 0.14 wt% (Lerner ). Depending on the composition of Ti in the alloy, this element could enhance the tensile strength properties or might have a detrimental effect on machinability due to the formation of very hard carbides and nitrides.…”

“…Furthermore, titanium normally has a strong effect on the solidified structure by increasing undercooling, thus promoting Type D graphite. However, in order to achieve this effect, it is necessary to decrease the percentage of the carbon equivalent (CE) in the alloy (<4.44%) (Lerner ). The ‘Thermal history’ section indicates that the CE was around 4.94, with a TiO 2 composition of 0.043 wt%, according to the fluorescence X‐ray results presented in Table .…”

“…No Al, Mg, C or O were detected within or surrounding the Ti particles. According to the literature (Lerner ), the occurrence of more angular‐shaped particles is characteristic of Ti–N particles such as those detected in the cannonballs. In fact, the well‐shaped Ti particles demonstrate a low Ti content in the grey cast iron alloy.…”

“…In fact, the well‐shaped Ti particles demonstrate a low Ti content in the grey cast iron alloy. Since Ti is a nitrogen scavenger, it eliminates porosity around the particles, thus reducing the local hardness (Lerner ) and tensile strength (Mikelonis ; Greenhill and Reynolds ). An increase in the Ti content results in the formation of more complex Ti compounds such as carbides or carbonitrides, which were not detected in the cannonballs.…”