Microstructural Evolution in Inconel 718 During Room-Temperature Tube Flow Forming: Plastic Flow Heterogeneities and Phase Evolution

A microstructural analysis of Inconel 718 tube flow forming is presented. The grain fragmentation analysis shows that the increase of the number of reduction passes allows a more homogenous distribution of strain which may explain the higher ductility observed when the number of reduction passes increases. Additionally, recrystallized grains and delta phase volume fraction increase were observed. This observation indicates a temperature increase and a very high increase of the delta phase precipitation kinetics.