TY - JOUR
T1 - Microstructural insights into creep of Ni-based alloy 617 at 700 °C provided by electron microscopy and modelling
AU - Riedlsperger, Florian
AU - Wojcik, Tomasz
AU - Buzolin, Ricardo
AU - Zuderstorfer, Gerold
AU - Speicher, Magdalena
AU - Sommitsch, Christof
AU - Sonderegger, Bernhard
N1 - Publisher Copyright:
© 2023
PY - 2023/4
Y1 - 2023/4
N2 - In this work, microstructural changes during creep of Ni-based alloy 617 at 700 °C and 165 MPa have been investigated by electron microscopy, and complementarily modelled. Precipitate types, sizes and chemistry were determined by transmission- (TEM) and scanning electron microscopy (SEM). Apart from γ’ particles, MX and carbides, coarse μ-phase was found. Grain size, frequency of twins, deformation patterns and geometrically necessary dislocations were characterized by electron backscatter diffraction (EBSD). Based on measurements and literature data, creep behavior and a time-to-rupture (TTR) diagram of A617 have been numerically simulated at 700 °C in a range of 165 to 215 MPa with a new physical model. Our new creep model achieved excellent agreement with measured data and literature in terms of predicted creep life, times to 1% strain, minimum creep rate and microstructural evolution. We also succeeded in considering the varying ductility of the material in a novel damage law by implementing the reduction of area from fractured creep samples. Diffusion creep (coble creep) is considered in addition to dislocation creep in the model. The impact of diffusion creep is mostly visible at low stresses, leading to significant improvements within the TTR diagram.
AB - In this work, microstructural changes during creep of Ni-based alloy 617 at 700 °C and 165 MPa have been investigated by electron microscopy, and complementarily modelled. Precipitate types, sizes and chemistry were determined by transmission- (TEM) and scanning electron microscopy (SEM). Apart from γ’ particles, MX and carbides, coarse μ-phase was found. Grain size, frequency of twins, deformation patterns and geometrically necessary dislocations were characterized by electron backscatter diffraction (EBSD). Based on measurements and literature data, creep behavior and a time-to-rupture (TTR) diagram of A617 have been numerically simulated at 700 °C in a range of 165 to 215 MPa with a new physical model. Our new creep model achieved excellent agreement with measured data and literature in terms of predicted creep life, times to 1% strain, minimum creep rate and microstructural evolution. We also succeeded in considering the varying ductility of the material in a novel damage law by implementing the reduction of area from fractured creep samples. Diffusion creep (coble creep) is considered in addition to dislocation creep in the model. The impact of diffusion creep is mostly visible at low stresses, leading to significant improvements within the TTR diagram.
KW - Alloy 617
KW - Creep modelling
KW - Dislocation density
KW - electron microscopy
KW - Ni-based alloys
KW - Precipitates
UR - http://www.scopus.com/inward/record.url?scp=85147849796&partnerID=8YFLogxK
U2 - 10.1016/j.matchar.2023.112720
DO - 10.1016/j.matchar.2023.112720
M3 - Article
AN - SCOPUS:85147849796
SN - 1044-5803
VL - 198
JO - Materials Characterization
JF - Materials Characterization
M1 - 112720
ER -