Experimental Investigation of Delta Phase Precipitation in Inconel 625 Superalloy Aged at 550, 625 and 725 °C

Author(s)

Renato Baldan ^[1] ; Antonio Augusto Araujo Pinto da Silva ^[2] ; Tiemi Manfio Tanno ^[3] ; Eliara Torres da Costa ^[4] ; João Victor Negri Brentegani ^[5] ; Antonio Augusto Couto ^[6]

Affiliation

^[1] Universidade Estadual Paulista. Câmpus Experimental de Itapeva - Brasil

^[2] Universidade Federal de Itajubá. Instituto de Engenharia Mecânica - Brasil

^[3] Universidade Estadual Paulista. Câmpus Experimental de Itapeva - Brasil

^[4] Universidade Federal de Itajubá. Instituto de Engenharia Mecânica - Brasil

^[5] Universidade Federal de Itajubá. Instituto de Engenharia Mecânica - Brasil

^[6] Universidade Presbiteriana Mackenzie. Escola de Engenharia - Brasil

• Document type: Journal article
• Source: MATERIALS RESEARCH-IBERO-AMERICAN JOURNAL OF MATERIALS; v. 23, n. 1 2020-05-29.

Abstract

Abstract The δ is an important stable phase that replaces the metastable γ'' in the microstructure of Inconel 625 superalloy. The present work aims to investigate the kinetic of δ-phase precipitation in the microstructure of Inconel 625 nickel-based superalloy aged at 550, 625 and 725 °C up to 1000 h. Aging temperatures were chosen based on the thermodynamic simulation using JMatPro software which indicated that this phase is stable at temperatures below 905 °C. Microstructure of the heat-treated samples was analyzed via SEM/EDS and microhardness evolution was performed by Vickers microhardness tests. The results have shown that the samples aged at 550 °C (all times), 625 °C (all times) and 725 °C up to 200 h did not presented microstructural evidences of δ precipitation. However, samples aged at 725 °C for 500 and 1000 h clearly presented an acicular δ-phase precipitated mainly at the grain boundaries. It was noted changes in the microhardness at different aging time and temperatures probably due to the presence of γ'' and/or δ phases. The sample aged at 625 °C for 1000 h presented the highest microhardness value (333 ± 10 HV). (AU)

• FAPESP's process: 18/07802-9 - Microstructural characterization, isothermal and cyclic oxidation resistance at high temperatures of conventional and Nb-modified MAR-M246 superalloys
• Grantee: Renato Baldan
• Support Opportunities: Regular Research Grants