Iranian Journal of Materials Science and Engineering

en Effect of Fine-Grained Area’s Dissolution after Solution Treatment Temperature on Tensile and Creep Life Enhancement of Hot Rolled Rene 65 گروه مکانیکی و شکل دادن Mechanical Performance and Formability of Materials Research Paper Research Paper 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. René 65 superalloy,fine-grained areas (FGAs),solution treatment,γ' precipitates,creep resistance. 0 0 http://ijmse.iust.ac.ir/browse.php?a_code=A-10-57-13&slc_lang=en&sid=1 Seyed Hossein Razavi hrazavi@iust.ac.ir 1800319475328460022850 1800319475328460022850 Yes Iran university of science and Technology (IUST) Mehdi Safavi Mehdi_safavi@iust.ac.ir 1800319475328460022851 1800319475328460022851 No Iran university of Science and Technology M. Reza Aboutalebi mrezab@iust.ac.ir 1800319475328460022852 1800319475328460022852 No Iran University of Science and Technology Seyed Mehdi Abbasi Sma_Abbasi@mut.ac.ir 1800319475328460022853 1800319475328460022853 No Malek Ashtar university