Dynamic recrystallization and precipitation in low carbon low alloy steel 26NiCrMoV 14-5

Hot working behavior of 26NiCrMoV 14-5 steel was investigated by performing hot compression testing at a temperature range of 850-1150 °C and strain rates of 0.001-1 s−1. The obtained flow curves at temperatures higher than 1000 °C were typical of dynamic recrystallization, whereas at lower temperatures the flow curves were representing work hardening without any indication of dynamic recrystallization. The apparent activation energy of the material was determined as 437 kJ/mol and the flow stress was correlated to strain rate and temperature using the hyperbolic sine function. The flow curves at high temperatures were successfully modeled using a combination of the Cingara and Avrami equations. However, at temperatures below 1000 °C, the predicted flow curves using the Cingara and Avrami equations were considerably different from the experimental curves. From the low work hardening rates and the increasing of flow stress at temperatures below 1000 °C the possibility of dynamic precipitation could be elucidated. This idea was corroborated by observing the different dependence of flow stress on temperature at low and high temperatures. In order to assess the potential of precipitation in the material stress relaxation tests were performed at low and high temperatures and the results confirmed the possibility of dynamic precipitation at temperatures below 1000 °C.