Deformation and Damage Mechanisms of High Temperature Alloys: Material Models
Sponsored by: TMS Structural Materials Division, TMS: High Temperature Alloys Committee
Program Organizers: Mark Hardy, Rolls-Royce Plc; Jonathan Cormier, ENSMA - Institut Pprime - UPR CNRS 3346; Jeremy Rame, Naarea; Akane Suzuki, GE Aerospace Research; Jean-Charles Stinville, University of California, Santa Barbara; Paraskevas Kontis, Norwegian University of Science and Technology; Andrew Wessman, University of Arizona

Tuesday 2:30 PM
March 1, 2022
Room: 304B
Location: Anaheim Convention Center

Session Chair: Paraskevas Kontis, Max-Planck-Institut fur Eisenforschung GmbH; Jonathan Cormier, ISAE-ENSMA & Institut Pprime

2:30 PM
Systematic Study of the Effect of Alloying on APB and SISF Energies in L1₂-(Co,Ni)₃(Al,W,Ta): K V Vamsi¹; Tresa Pollock¹; ¹University of California-Santa Barbara
    The presence of ordered γ′ (L1₂) results in various precipitate shearing modes involving planar faults in Ni-, Ni-Co and Co-base superalloys. Planar fault energies (PFEs) are sensitive to the composition of the precipitate and thereby results in unique deformation mechanisms. Antiphase boundary (APB) coupled shear and stacking fault ribbons involving both APB and superlattice intrinsic stacking faults (SISFs) are often reported in CoNi-base superalloys. Additionally, microstructural characterization reveals a certain degree of chemical segregation in the vicinity of the planar faults. Given the importance of planar defects and the lack of knowledge of planar fault energies in CoNi-base superalloy compositions, the present work employs a novel diffuse multi-layer fault (DMLF) model to calculate APB and SISF energies using proximate γ_a^', D0₂₄, structures as approximations to APB and SISF. The PFEs in (Co,Ni)₃(Al,W,Ta) are evaluated using first-principles calculations, and the implications for alloy design will be discussed.

2:50 PM
A Physics-based Vacancy Diffusion Model to Capture High Temperature Creep Responses: Application to 316H Stainless Steel: Aritra Chakraborty¹; Mariyappan Arul Kumar¹; Ricardo Lebensohn¹; Laurent Capolungo¹; ¹Los Alamos National Laboratory
    The deformation response of a material under creep conditions at relatively high homologous temperatures and low stresses is primarily diffusion dominated. In this work, we capture the experimentally observed creep response of 316H under such conditions using a full–field physics-based point defect diffusion model, integrated within an elasto-viscoplastic fast Fourier transform based (EVPFFT) framework. The chemo-mechanical kinematic coupling is incorporated via the diffusion strain rate tensor (consisting of hydrostatic and deviatoric components) into the total strain rate using additive decomposition under the small-strain framework. The model not only captures Nabarro–Herring (lattice) and Coble (grain boundary) creep but also allows to correctly quantify the dislocation climb contribution using the actual vacancy concentration. Furthermore, we compare the scaling response of our diffusion model with stress, temperature, and grain size using 2D polycrystal simulations, and compare the results with that of reported on Nabarro–Herring creep.

3:10 PM  Cancelled
Damage-coupled Monotonic and Cyclic Softening Modeling in Inconel 718 Superalloys: Jean-Briac le Graverend¹; ¹Texas A&M University
    IN 718 experiences cyclic and monotonic softening. Each phenomenon is usually modeled via distinct constitutive equations. A new constitutive model is proposed to model the two phenomena at once in a crystal-plasticity framework, therefore reducing the number of required parameters. The new model is coupled to a damage density function and tested on creep, monotonic, and cyclic loadings at 650C. The effect of texture is also discussed.

3:30 PM
Phase Field Modeling of Void Growth under Creep: Tianle Cheng¹; Fei Xue²; Jeffrey Hawk³; Youhai Wen³; ¹U.S. Department of Energy, National Energy Technology Laboratory / NETL Site Support Contractor; ²U.S. Department of Energy, National Energy Technology Laboratory / ORISE; ³U.S. Department of Energy, National Energy Technology Laboratory
    Creep damage and rupture is one of the major concerns for alloys applied at high temperatures. Void growth and coalescence are known to be the critical mechanisms for creep damage. In the literature, analytical or numerical models for void growth under creep often take strong assumptions for the shapes of voids and grains, or only consider one of the growth mechanisms (diffusion or plasticity). Here we develop a multi-phase-field model for void growth under creep that incorporates material microstructure, surface and GB diffusion, as well as crystal plasticity. Simulation results are compared to previous reports based on other methods such as the dilatational plasticity models, finite element models and analytical models. The influence of surface tension and surface diffusion on the void growth rate and morphology evolution under different triaxialities of remote stress are studied. The size effects on void growth under creep are discussed.

3:50 PM
Numerical Studies to Analyze the Deformation Behavior of Corroded Material under High Velocity Impact Using Continuum Damage Mechanics: Yogeshwar Jasra¹; Pardeep Kumar²; Paras Mohan Jasra³; Ravindra Kumar Saxena¹; ¹Sant Longowal Institute of Engineering and Technology; ²R.V. Industries; ³DOTec Corp
    The fracture initiation and propagation process in the corroded nuclear structure material when impact by a high-velocity blunt shaped projectile is simulated in the present research. The impact process results in the crack propagation and fragmentation in the target material. Additionally, the corrosion in the material degrades the overall mechanical and ballistic performance of the structures. The effect of corrosion in the material has also been analyzed. During impact, the target material undergoes large deformation, resulting in the evolution of the ductile damage and ultimately leading to the fracture. The fracture in the material is simulated using CDM at the velocity range of 200-600 m/sec. The effect of inherent voids evolved due to corrosion on the ballistic behavior has also been presented. It is found that the cracks propagate due to the presence of inherent voids in the target body. The corrosion degrades the ballistic performance of the target body.