Microstructure and mechanical properties of difficult to weld Rene 77 superalloy produced by laser powder bed fusion
| Autor: | Jose Alberto Muñiz-Lerma, Mathieu Brochu, Sıla Ece Atabay, Oscar Sanchez-Mata |
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| Rok vydání: | 2021 |
| Předmět: |
010302 applied physics
Materials science Mechanical Engineering Alloy 02 engineering and technology engineering.material 021001 nanoscience & nanotechnology Condensed Matter Physics Microstructure 01 natural sciences Carbide Superalloy Mechanics of Materials 0103 physical sciences Ultimate tensile strength engineering General Materials Science Grain boundary Texture (crystalline) Composite material 0210 nano-technology Ductility |
| Zdroj: | Materials Science and Engineering: A. 827:142053 |
| ISSN: | 0921-5093 |
| DOI: | 10.1016/j.msea.2021.142053 |
| Popis: | Fabrication of γ′ precipitation strengthened nickel-based superalloys via laser powder bed fusion still remains a challenge. In this study, Rene 77, a high γ′ containing superalloy that is considered as difficult to weld, was processed by laser powder bed fusion. Crack-free parts with high density were fabricated without any compositional modifications or preheating of the built plate. This defect-free structure was maintained upon solutionizing and aging heat treatment. The microstructure of the samples has been characterized in detail following the fabrication and after the heat treatment. Scanning electron microscopy analysis revealed that the as-built microstructure consists of columnar grains mainly aligned in the direction along with extremely fine γ′ precipitates and spherical cell boundary carbides. The grain structure and texture were unaffected by the applied heat treatment due to the pinning effect exerted by the carbide particles. Development of a bimodal γ′ distribution including cuboidal primary and spherical secondary precipitates was observed in the heat-treated sample. Additional carbide formation as a discontinuous grain boundary film was also seen. Tensile deformation behavior for both conditions was also tested at room temperature and 810 °C. Measured strength values for all test conditions were higher compared to a wrought and heat-treated alloy tested at room temperature. The as-built sample showed hardening and loss of ductility during elevated temperature testing due to γ’ precipitation at the test temperature. The microstructure of the heat-treated sample was not altered during testing at 810 °C. However, improved elongation behavior and transition in fracture mode from cleavage to ductile fracture were observed due to microtwin formation at elevated temperatures. |
| Databáze: | OpenAIRE |
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