Morteza Hadi, Omid Bayat, Hadi Karimi, Mohsen Sadeghi, Taghi Isfahani,
Volume 19, Issue 1 (3-2022)
Abstract
In this research, the effect of initial microstructure and solution treatment on rollability and crystallographic texture of a Cu-Mn-Ni-Sn alloy has been investigated. The initial tests indicated that the rolling of the alloy at different temperature conditions is not possible due to formation of second phases. Herein to eliminate the segregated phases, according to DTA analysis, proper temperature for solution treatment was selected as 750°C applied at different periods of time. The obtained results showed that after 15-hour solution treatment, the complete elimination of Sn, Mn, Ni, and Fe-rich phases can be achieved. Also, the peaks of XRD shifted to the higher angles indicating that the alloying elements are dissolved. Meanwhile, the intensity of the texture reduced and the dominant texture changed from Goss and Brass-texture to Copper-texture. Accordingly, the amount of maximum total reduction at the rolling process increased from 16.37 to 109.46 after solution treatment.
Seyed Hossein Razavi, Mehdi Safavi, M. Reza Aboutalebi, Seyed Mehdi Abbasi,
Volume 21, Issue 0 (3-2024)
Abstract
This study examines how solution treatment temperature affects the dissolution of fine-grained areas (FGAs) that form during hot rolling of René 65 nickel-based superalloy. These FGAs, which are rich in sub-micron to micron-sized primary γ' precipitates (γ'I) and located mainly in shear bands, remained stable after sub-solvus treatments below 1055 °C. They dissolved gradually with increasing temperature and disappeared completely above 1115 °C. The resulting microstructural changes, along with high-temperature tensile properties and creep behavior in the 1055–1115 °C range (followed by aging at 760 °C for 8 h), were evaluated. Raising the solution temperature reduced the FGA volume fraction and improved tensile elongation, while yield strength (YS) and ultimate tensile strength (UTS) remained largely unchanged. At 1095 °C, creep life at 730 °C / 530 MPa exceeded 100 h without fracture and exhibited a notably lower steady-state creep rate. These improvements appear linked to the elimination of secondary γ' depleted zones around the former FGAs, which produced a more uniform secondary γ' distribution, greater crack path deflection, and continued Zener pinning by remaining primary precipitates. However, solution treatment at 1115 °C caused grain growth and coarsening of secondary precipitates, which reduced creep performance. Overall, 1095 °C provided the best compromise for microstructural uniformity and balanced high-temperature properties in hot-rolled René 65.
