FE modelling of large ingot hot forging

Hot forging of large ingots made of high temperature resistant steels is gaining renewed attention due to the increasing demand of large products mostly for the power industry. Hot forging is chosen among different manufacturing processes thanks to its potentialities in producing sound components characterized by excellent mechanical properties. Nevertheless, one of the most critical issues lies in the presence of shrinkage cavities and porosities inside the ingot that must be closed and healed completely during forging in order to avoid catastrophic failure of the component during its service life. The paper presents the FE modeling of the cogging process applied to a large component made of a duplex steel. An accurate calibration of the model in terms of material rheology and microstructure helps in quantifying the ranges of variables that are recognized to affect the closure and bonding of internal voids. A procedure is proposed to evaluate the recrystallized fraction of duplex steels which is likely to affect the goodness of such closure and bonding.