Twin boundary characters established during dynamic recrystallization in a nickel alloy

• Twin boundary characters are studied in nickel alloy during DRX via EBSD.
• Twin boundaries retain high coherency and mutual interaction is rather limited.
• Σ3 twin boundary length density is inversely proportional to DRX grain size.
• Σ3 twin boundary length fraction was found varying limitedly within a small range.

For the purpose of providing fundamentals for grain boundary engineering design for high-temperature alloys, twin boundary characters are studied quantitatively in a nickel alloy during DRX to improve the understanding of twin boundary evolution during hot deformation. The nickel alloy samples were hot compressed at temperatures of 1120–1180 °C and strain rates of 0.1 s− 1 and 1 s− 1 to a fixed true strain of 1.1. Refined equiaxed grain structure is obtained with abundant twin boundaries. Most of the twin boundaries form inside the grains, being highly coherent and showing rather limited mutual interaction. An inversely proportional relationship is found between Σ3 twin boundary length density (BLDΣ3) and DRX grain size (DDRX). An analytical model is derived here, in good agreement with current experimental results, indicating that the stored strain energy difference across grain boundary is the main driving force for grain boundary migration and determines the annealing twin formation during DRX. Σ3 twin boundary length density (BLFΣ3) developed in DRX was found varying within a small range of 44%–48%, which is shown to result from the inverse proportionality between grain boundary length density (BLDGB) and DDRX as well as the inverse proportionality between BLDΣ3 and DDRX.