GH4738合金薄带材因宽厚比大，在热加工过程中存在温降快的特点，易从γ′单相区降低至γ+γ′双相区，从而导致热裂敏感性高和组织不均，针对上述问题，本文采用Gleeble-3800热模拟试验机在950~1100 ℃、0.01~10 s^-1条件下进行热压缩实验，结合OM、SEM及EBSD表征技术，系统研究了合金从亚固溶到过固溶区的组织演变规律和动态再结晶(DRX)机制，并基于动态材料模型构建了热加工图。结果表明：流变应力随温度升高而降低，在γ′相回溶温度(~1034 ℃)附近降幅最大(>150 MPa)；基于Arrhenius双曲正弦模型建立的本构方程相关性良好(R² > 0.98)，并计算得到热变形激活能为796.75 kJ/mol。热加工图分析表明，合金在温度950~954 ℃，应变速率0.01~0.3 s^-1变形条件下为流变失稳区，其余参数范围内均为安全加工区；在温度1040~1095 ℃、应变速率0.14~0.61 s^-1时，合金的功率耗散效率较高且组织均匀，为该合金的最优热加工窗口。在亚固溶温度下合金以晶界弓弯为特征的非连续动态再结晶(DDRX)机制为主，此时再结晶程度较低；在过固溶温度下DRX较为充分，但在高速率下因变形时间短导致晶粒尺寸分布不均匀，此时DRX过程存在连续动态再结晶机制(CDRX)。高速率变形通过增大储存能促进再结晶形核，但温升效应使晶粒略有粗化。本研究可为GH4738合金热轧宽幅带材终轧温度控制及工艺优化提供理论依据。

Owing to the large width-to-thickness ratio, GH4738 alloy thin strips experience rapid temperature reduction during hot working, readily transitioning from the γ′ single-phase region to the γ+γ′ dual-phase region, thereby leading to high hot cracking sensitivity and microstructural inhomogeneity. To address these issues, hot compression tests were conducted on a Gleeble-3800 thermomechanical simulator at temperatures of 950~1100 ℃ and strain rates of 0.01~10 s^-1. Combined with OM, SEM, and EBSD characterization techniques, the microstructural evolution and dynamic recrystallization (DRX) mechanisms from the sub-solvus to super-solvus regions were systematically investigated, and a hot processing map was constructed based on the dynamic material model (DMM). The results indicate that the flow stress decreases with increasing temperature, with the most significant reduction (>150 MPa) observed near the γ′ dissolution temperature (~1034 ℃). The constitutive equation established based on the Arrhenius hyperbolic sine model exhibits excellent correlation (R² > 0.98), yielding a hot deformation activation energy of 796.75 kJ/mol. Hot processing map analysis reveals that the alloy exhibits flow instability in the temperature range of 950~954 ℃ and strain rates of 0.01~0.3 s^-1, whereas safe processing occurs under other parameter conditions. The optimal hot processing window is identified at temperatures of 1040~1095 ℃ and strain rates of 0.14~0.61 s^-1, where the alloy exhibits high power dissipation efficiency and homogeneous microstructure. In the sub-solvus temperature regime, the alloy primarily exhibits discontinuous dynamic recrystallization (DDRX) characterized by grain boundary bulging, resulting in limited recrystallization; under super-solvus conditions, DRX proceeds more completely, but grain size heterogeneity occurs at high strain rates due to insufficient deformation time, with the DRX process involving continuous dynamic recrystallization (CDRX) mechanisms. High strain rate deformation promotes recrystallization nucleation through increased stored energy, though adiabatic heating effects cause slight grain coarsening. This study provides a theoretical basis for the finish rolling temperature control and process optimization of GH4738 alloy thin strips.