Hot Deformation Behavior, Dynamic Recrystallization, and Texture Evolution of Ti–22Al–25Nb Alloy

Abstract

The hot deformation behavior, dynamic recrystallization, and texture evolution of Ti-22Al-25Nb alloy in the temperature range of 950-1050 C and strain rate range of 0.001-1 s À1 is investigated by plane-strain compression testing on the Gleeble-3500 thermo-mechanical simulator. The results show that the flow stress decreases with the increase of temperature and decrease of strain rate. Besides, the flow curves appear a serrate oscillation at a strain rate of 0.1 s À1 for all the temperature ranges, which may result from instability such as flow localization or micro-cracking. The flow behavior can be expressed by the conventional hyperbolic sine constitutive equation and the calculated deformation activation energy Q in the (a 2 þ B2) and B2 regions are 631.367 and 304.812 kJ mol À1 , respectively. The microstructure evolution is strongly dependent on the deformation parameters, and dynamic recrystallization (DRX) is the dominant softening mechanism in the (a 2 þ B2) region, including discontinuous dynamic recrystallization (DDRX), and continuous dynamic recrystallization (CDRX). In addition, the h bcc -fiber of {110} <001> is the dominant texture component in deformed Ti-22Al-25Nb alloy. It is observed that the weakening of the deformation texture is accompanied by the occurrence of DRX, which can be attributed to the large misorientation between DRX grains and neighboring B2 matrix induced by the rotation of DRX grains toward the preferred slip systems.

Constitutive Model and Processing Maps for a Ti‐55511 Alloy in β Region

“…Combining Equation (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14), the dislocation density-based constitutive equation can be summarized as 8 > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > < > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > :…”

Hot deformation behavior and processing maps of iron‐nickel based superalloy

“…By the increase of the strain rate, the flow softening phenomenon was observed at low temperatures. Flow softening followed by a steady state flow stress is due to the occurrence of dynamic re- covery and dynamic recrystallization; whereas a continuous descending flow curve is a sign of flow localization resulted in cracks and adiabatic shear bands [27][28]. Such conditions may exist in specimens deformed at 850°C-950°C with strain rates around 0.1 s À 1 , and section 3.3 will discuss these possibilities.…”

Subdivision of Dynamic Recrystallization Mechanism in the Transition Zone and Microstructure Evolution of Incoloy825 Alloy

“…[4][5][6][7][8][9][10] Recently, many scholars have reported the DRX and microstructure evolution of different alloys. For example, DRX behavior is studied in nickel-base alloy, [11][12][13] stainless steel, [4] magnesium alloy, [14] aluminum alloy, [5,15] titanium alloy, [16,17] and recrystallization kinetics is established to predict DRX fraction. It can be found that the microstructure evolution in the process of DRX is closely related to processing parameters, such as deformation temperature, strain rate, and strain.…”