Creep Damage Assessment of Notched Material Made of a Solidification Control Ni-Base Superalloy Using the EBSD Method

Abstract

Intermittent EBSD assessment of creep damage behavior was performed on five kinds of notched specimens of a Ni-base superalloy DS material. As a result, it was found that the fixed area average intra-grain misorientations (GROD_ave) of the notched damaged material corresponded to the NOD (Notched Opening Displacement). In addition, a misorientation parameter (GROD_ave/φ₀) normalized with the initial notch opening value was able to express creep curves regardless of the notch geometries as well as the RNOD (Relative Notched Opening Displacement). Furthermore, a misorientation parameter (∫GROD_ext/φ₀) normalized with the initial notch opening value after extracting the GROD value exceeding a threshold on the GROD map was proposed. It was concluded that the damage assessment parameter of ∫GROD_ext/φ₀ uniformly allowed creep damage assessment by generally defining the damage evaluation area even for actual components with various stress concentrated areas.