Superalloys 2024: General Session 9: Additive Manufaturing I
Program Organizers: Jonathan Cormier, ENSMA - Institut Pprime - UPR CNRS 3346
Wednesday 6:30 PM
September 11, 2024
Room: Exhibit Hall
Location: Seven Springs Mountain Resort
Session Chair: Yuanbo Tang, University of Birmingham; Timothy Smith, NASA Glenn Research Center
6:30 PM
A Physics-based, Probabilistic Modeling Approach to Design, Manufacture, and Certify AM Components: David Furrer1; Masoud Anahid2; S. Burlatsky2; Manish Kamal1; 1Pratt & Whitney; 2Raytheon Technologies
Additive manufacturing (AM) has captured the imagination of many in the materials, manufacturing and design communities. While AM has shown significant potential to produce complex geometries from a wide range of materials, the stringent requirements of production components necessitate advances in the way components are designed, manufactured, and certified. Dynamic properties of AM components are known to be significantly hindered by the presence of build defects. An integrated computational materials engineering (ICME) approach to AM has been pursued through which build defects can be accurately predicted on a component location-specific basis. This capability is leading to a model-based material definition (MBMD) approach to process design and control, and subsequent component qualification and certification. The development and demonstration of component and process manufacturing design examples of this approach for a nickel-base superalloy case application will be provided.
6:55 PM
3D Characterization of Defects and Microstructure in High Density LPBF Prints of a CoNi Alloy: James Lamb1; Evan Raeker1; Kira Pusch1; McLean Echlin1; Stephane Forsik2; Ning Zhou2; Austin Dicus2; Tresa Pollock1; 1University of California Santa Barbara; 2Carpenter Technology Corporation
Laser powder bed fusion (LPBF) printing defects are investigated through multimodal 3D serial sectioning data on a model CoNi alloy. Defect segmentation across three different LPBF prints with different scan strategies, in which interlayer rotation and the presence of a contour scan is varied, reveal fully dense microstructures (>99.8% dense). Despite being in a density range commonly considered as fully dense material, these prints contain an array of small pores, lack-of-fusion defects, and cracks that can be highly anisotropic. Their size and number are compared to those found in conventional superalloy casting techniques (investment casting, single crystal Bridgeman casting). In the AM samples, most pores and cracks have a thickness on the order of 3-6 μm, beyond the resolution capabilities of most industrial non-destructive evaluation techniques. A comparison between 3D and 2D defects measurements is included, revealing significant variability between 2D measurements and the ground truth 3D data. A state-of-the-art machine learning framework, U-Net, is implemented for defect segmentation within three TriBeam tomography datasets containing backscattered electron images with variable contrast conditions. U-Net results indicate high fidelity defect segmentation within all three datasets where recall and precision are >85%. The 3D reconstructions of the CoNi alloy samples provide insight into the defect content that can be expected from high-quality fully dense LPBF printed superalloy material.
7:20 PM
The Relationship Between Strain-age Cracking and the Evolution of γ' in Laser Powder-Bed-Fusion Processed Ni-based Superalloys: Jonathon Markanday1; Neil D'Souza2; Nicole Church1; James Miller1; Jessica Pitchforth1; Leigh Connor3; Stefan Michalik3; Bryan Roebuck4; Nicholas Jones1; Katerina Christofidou5; Howard Stone1; 1University of Cambridge; 2Rolls-Royce; 3Diamond Light Source; 4National Physical Laboratory; 5University of Sheffield
Factors affecting strain-age cracking (SAC) have been quantitatively assessed in a range of Ni-base superalloys with differing contents. Differences in the amount of present in the as-built condition of HA282, STAL 15DE, CM247LC and IN713LC are highlighted. In the as-built condition, are absent in HA282, but appear as nano-clusters in IN713LC. On heating, precipitates coherently in the phase, increasing the yield strength. The kinetics of precipitation are dependent on the heating rate and precipitation terminates at different temperatures in different alloys. The propensity to SAC is assessed via volume changes accompanying precipitation, increase in elastic modulus accompanying precipitation and a loss in ductility/grain boundary cohesive strength with increasing temperature. A marked feature of additively built microstructures is the dramatically low grain boundary cohesive strength at 800 C, which is related to the segregation within the terminal liquid film at the grain boundary. The most important factor contributing to SAC is the lack of ductility and reduced grain boundary cohesive strength.