Influence of deformation temperature on recrystallization in a Ni-based single crystal superalloy

Experimental and Numerical Studies on Recrystallization Behavior of Single-Crystal Ni-Base Superalloy

“…Besides, the strengthening effect of γ’ phases increases the superalloy strength at elevated temperature, and the γ’ phases play a role of second phase particles which can lead to an increase of dislocation density in the deformed matrix by several orders of magnitude as dislocations pass around the particles. Hence the equivalent strain induced at elevated temperatures can produce a higher dislocation density and stored energy compared to RT, which conforms with the TEM observation of Cox’s [ 44 ] and Li’s [ 34 ] studies. The simulation results present the same tendency, that the calculated stored energy of S-RT and S-980 are 1.56 × 10 6 J/m 3 and 2.75 × 10 6 J/m 3 , respectively.…”

“…The samples deformed at different temperature show different RX behavior during the SSHT procedure. Cox [ 44 ] and Panwisawas [ 16 ] drew the conclusion that RX grains tend to occur in the samples deformed at elevated temperatures, while Li [ 34 ] found the highest RX propensity occurs in the samples deformed at 980 °C for DD6 superalloy. From TEM observation it is inferred that a large amount of stacking faults induced at 980 °C could facilitate RX through thermal twinning nucleation [ 34 ].…”

“…P c is the critical stored energy for RX nucleation following , where ε c and E low denote the critical plasticity and low-angle grain-boundary energy, respectively. The critical temperature for RX nucleation was determined according to the experimental results of isothermal heat treatment in Reference [ 34 ], and those of S-RT and S-980 with 5% plastic deformation are 1310 °C and 1260 °C, respectively.…”

Processing of directionally cast nickel-base superalloys: solidification and heat treatments

“…typically 6 hours at 1315 °C in case of CMSX-4 alloy [48]. But compressive and tensile tests were also tested at several temperatures, followed by isothermal annealing heat treatments for various parameters (holding time and duration) [48][49][50]. The presence of recrystallized grains is found to depend on i-the plastic strain, ii-the annealing temperature, and iii-the temperature at which the specimens were deformed.…”

Visco-plasticity during in-situ cooling from solidification of a nickel-base single crystal superalloy using neutron diffraction

“…Cooling rates [3] and dendritic growth rates [4,5] can be controlled through optimising the furnace parameters and appropriate component design to minimise defects in single-crystal castings that also conform to acceptable dimensional tolerance. On cooling during and after solidification of a single crystal superalloy casting, little is known about the in-situ introduction of high temperature deformation [6,7] and the quantification of processing-induced deformation [8]. To the best of the authors' knowledge, finite element calculations that determine thermo-mechanical behaviour are traditionally contingent on the quality of the as-cast materials data and thermo-physical properties used in the model [9].…”