Static Recrystallization in Incoloy 800H: Insights from High-Throughput Macroscale Deformation Gradient Study

Abstract High-throughput graded tensile samples were used to measure the response of Incoloy 800H to annealing after cold work. Macroscale strain gradients between $$\sim 0\%-27\%$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>∼</mml:mo> <mml:mn>0</mml:mn> <mml:mo>%</mml:mo> <mml:mo>-</mml:mo> <mml:mn>27</mml:mn> <mml:mo>%</mml:mo> </mml:mrow> </mml:math> von Mises strain were tested. For these strains, full recrystallization did not occur for annealing at 1050°C or 1075°C for times up to 2 h, while full recrystallization was observed after 1 h at 1100°C. Strain–time–temperature relationships for initiation and completion of recrystallization were obtained from EBSD and hardness characterization. Special boundary fractions were analyzed for each thermomechanical condition, showing the potential of gradient samples to accelerate grain-boundary engineering studies. Extensive M 23 C 6 precipitation was observed in samples annealed at 1050°C and 1075°C, and appeared to retard recrystallization. Dissolution of M 23 C 6 was observed at 1100°C, contributing to rapid recrystallization. Relationships for recrystallized hardness and grain diameter were also developed. Prior to this study, little data on the response of Incoloy 800H to heat treatment after cold work has been published, despite it being a workhorse alloy in many industries. It is hoped that manufacturers in these industries can use this work as a guide to select optimal thermomechanical conditions for their cold-worked components.