Deformation and Damage Mechanisms of High Temperature Alloys: Crystal Plasticity, Micro-mechanics & Environmental Behavior
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, Safran Aircraft Engines; Akane Suzuki, GE Research; Jean-Charles Stinville, University of California, Santa Barbara; Paraskevas Kontis, Norwegian University of Science and Technology; Andrew Wessman, University of Arizona

Wednesday 8:30 AM
March 2, 2022
Room: 304B
Location: Anaheim Convention Center

Session Chair: Andrew Wessman, University of Arizona; Mark Hardy, Rolls-Royce

8:30 AM  
Grain Scale Deformation Study of a Nickel-based Superalloy under Thermo-mechanical Fatigue Utilizing Crystal Plasticity Simulations and High-energy X-ray Diffraction Microscopy: Brandon Mackey1; Ritwik Bandyopadhyay1; Sven Gustafson1; Michael Sangid1; 1Purdue University
    Nickel-based superalloys are used for applications in the hot sections of gas turbines because of their high strength at elevated temperatures. These materials are subjected to complex thermo-mechanical loading due to service conditions which leads to thermo-mechanical fatigue (TMF) failure. The failure mechanisms associated with TMF are dependent on microstructural characteristics and parameters such as temperature, strain range, and strain-temperature phasing. Using microstructural information reconstructed from a high-energy X-ray diffraction microscopy (HEDM) TMF experiment, we generate a temperature-dependent crystal plasticity model for LSHR, a Nickel-based superalloy, to study failure mechanisms associated with TMF. HEDM grain average metrics at unique loading steps are compared to the crystal plasticity model to identify both the model and experimental capabilities associated with TMF. This framework provides the ability to pinpoint complex thermo-mechanical failure mechanisms at the grain scale.

8:50 AM  
A Framework to Enable Location-specific Analysis of Components by Incorporating Microstructural Information during the Product Design Cycle: Saikiran Gopalakrishnan1; Ritwik Bandyopadhyay1; Michael Sangid1; 1Purdue University
    Traditionally, aerospace components are treated as monolithic structures during lifing, wherein microstructural information at individual locations are not necessarily considered. The resulting design is conservative, leading to under usage of the component’s capabilities. To push the design limit, a location-specific lifing framework is developed, which tracks and retrieves manufacturing process and microstructural information at distinct locations for use within a crystal plasticity fatigue life prediction model. A use case for lifing dual microstructure heat treated LSHR turbine disk component is demonstrated at two locations, near the bore (fine grains) and near the rim (coarse grains) regions. We employ the framework to access (a) the grain size statistics and (b) the macroscopic strain fields to inform precise boundary conditions for the crystal plasticity finite-element analysis. The illustrated approach to conduct location-specific predictive analysis of components presents opportunities for tailoring the manufacturing process and resulting microstructures to meet the component’s targeted requirements.

9:10 AM  
Temperature Dependence of Tensile and Fatigue Properties of Additively Manufactured Ni-base Superalloys: A Comparative Study: Reza Ghiaasiaan1; Arun Poudel1; Nabeel Ahmad1; Muztahid Muhammad1; Paul Gradl2; Shuai Shao1; Nima Shamsaei1; 1Auburn University; 2NASA Marshall Space Flight Center
    Additive Manufacturing (AM) is uniquely appealing for Ni-base superalloys, whose applications often require complex shapes and impose significant production costs due to the alloys’ poor machinability. In this work, the tensile and fatigue behaviors of several additively manufactured (AM) Ni-superalloys at temperatures ranging from cryogenic to elevated temperatures were investigated and compared. These alloys include Hastelloy X, Haynes 282, Inconel 718, and Inconel 625 produced via two AM processes namely laser powder bed fusion (L-PBF) and laser powder direct energy deposition (LP-DED). Thorough analyses on micro-/defect-structure as well as mechanical response under static/cyclic axial loads were performed. This study aimed to provide understanding of process-structure-property relationships for these AM alloys in two regards: (1) the micro-/defect-structural evolution as the result of thermal cycles has been studied based on scanning electron microscopy and x-ray computerized tomography, (2) both fatigue and tensile properties were attempted to be correlated with micro-/defect-structure.

9:30 AM  
The Effect of Environment on the Near-crack Deformation Induced during Dwell Fatigue of a Ni-base Superalloy: Zachary Harris1; Philippa Reed2; James Burns1; 1University of Virginia; 2University of Southampton
    The effect of environment on the near-crack deformation induced during dwell fatigue of low solvus, high refractory (LSHR) superalloy specimens was assessed using electron backscatter diffraction (EBSD)-based approaches. Dwell fatigue experiments completed at 725C using a 1-90-1-1 trapezoidal waveform in laboratory air and vacuum (<0.05 Pa) were interrupted at a ΔK ≈ 40-44 MPam. Broad-scale EBSD was performed along the crack path, revealing that the magnitude and extent of deformation (quantified via kernel average misorientation) were systematically reduced for the specimen tested in vacuum. An evaluation of the geometrically necessary dislocation (GND) density in the crack-tip region was then conducted using cross-correlation-based high resolution EBSD, further underscoring the differences in near-crack deformation induced between the two environments. Results of this near-crack analysis are then evaluated in the context of the proposed role of crack tip oxidation on the dwell fatigue behavior of nickel-base superalloys.

9:50 AM Break

10:10 AM  
Frictional Ignition of Superalloys in High-pressure, High-temperature Oxygen: Zachary Cordero1; Andres Garcia-Jimenez1; 1Massachusetts Institute of Technology
    Oxidizer-rich and full-flow staged combustion rocket engines offer advantages in efficiency, thrust, and reusability over conventional gas generator engines. However, extreme combinations of O2 pressure and temperature in the ox-rich turbopump can limit engine life due to problems with metal ignition, burning, and oxidation-assisted fatigue. This talk will summarize initial insights from our investigation into the underlying mechanisms of frictional ignition, one of the ignition mechanisms of greatest concern and the root cause of several recent launch failures (Sea Launch’s NSS-8 and Orbital’s Orb-3). We test whether frictional ignition results from a breakdown of the oxide tribolayer that forms during a rubbing event using high-speed frictional ignition experiments, post-mortem characterization of recovered specimens, continuum mechanics models of sliding contacts, and thermochemical calculations of the structure and stability of oxide tribolayers. Our results suggest novel ignition-resistant superalloys for the next generation of reusable rocket engines.

10:30 AM  
Contributions of Oxidation and Creep to High Temperature Fatigue Crack Susceptibility in Waspaloy: Alex Jennion1; Zachary Harris1; James Burns1; 1University of Virginia
    The aggressive mechanical and environmental conditions in the hot sections of jet engines leads to creep and oxidation enhanced fatigue damage on high-performance metal components. Understanding the relative contribution of oxidation, cyclic damage accumulation, and creep is needed. Crack growth kinetics data were gathered on SENT fracture mechanics specimens using the direct current potential difference method. Specimens were tested in lab air and vacuum at elevated temperature at a constant ΔK and loaded according to a trapezoidal waveform with dwells ranging from 1 to 300 seconds. Plastic deformation and dislocation cell structure along the crack wake was assessed using high resolution electron backscatter diffraction and TEM. Quantitative comparisons of crack growth kinetics and deformation character for each test condition are performed and provide insight into the contribution of creep and oxidation to crack growth in the context of understanding and modeling high temperature fatigue behavior.

10:50 AM  
Microstructural and Mechanical Aspects of Damage Mechanisms In Dwell-fatigue In Inconel 718: Melanie Bordas-Czaplicki1; Jonathan Cormier2; Patrick Villechaise2; Vincent Roue3; 1Safran Aircraft Engines - Institut Pprime; 2Institut Pprime; 3Safran Aircraft Engines
    Damage mechanisms in dwell-fatigue applied to DA718 Inconel alloy has been investigated. All tests were carried out at 650 C, in stress-controlled mode, trapezoidal waveform at Rσ=0.05 and hold times between 1s and 90s. Damage in dwell-fatigue originates from oxidation, fatigue and creep. The increase in dwell-time at maximum stress leads to a transition from fatigue-dominated to creep dominated damage, overall reducing the cyclic life and increasing the plastic strain rate. All crack initiations were at surface or sub-surface particles, especially at carbides/nitrides. In order to understand damage mechanisms and implication of each phenomenon, interrupted tests were introduced. It has been possible to find a consistency between a transitional cumulative plastic strain, obtained around minimum strain rate, and damage mechanisms.

11:10 AM  
Numerical Studies to Predict the Fracture Behavior due to Stress Corrosion Cracking under Different Environmental Conditions: Sorabh Singhal1; Yogeshwar Jasra1; Pardeep Kumar2; Ravindra Kumar Saxena1; 1Sant Longowal Institute of Engineering and Technology; 2R. V. Industries
    Stress corrosion cracking (SCC) is a widely observed problem in many industrial applications. The SCC studies are performed to ensure the safe design of the structures under stress conditions. In the present work, a numerical study is performed to analyze the SSC behavior of the material degraded under different environmental conditions. The continuum damage mechanics approach is applied to simulate the behavior of the structures. The effect of properties degradation due to environmental conditions is incorporated using different mathematical models. The finite element simulation is performed on the plate under a stressed corrosive environment. The void initiation and propagation are simulated under different loading conditions. The time taken by the voids to grow into cracks reduces with increasing the constant load. Further, it is found that the corrosive environment adversely affects the performance of the material.