Post-rolling annealing optimization and its influence on microstructure, texture, and strength–ductility synergy of Nb–10Hf–1Ti refractory alloy sheets processed under different strain paths

The influence of rolling strain path on the microstructure, texture, recrystallization behavior, and tensile properties of a Nb–10Hf–1Ti alloy sheet was investigated. Unidirectional rolling (UR) produced continuous lamellar bands with a dominant <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mo fence="false" stretchy="false">{</mml:mo> <mml:mn>111</mml:mn> <mml:mo fence="false" stretchy="false">}</mml:mo> </mml:math> (γ-fiber) texture, whereas cross rolling (CR) disrupted band continuity and promoted a strong rotated cube <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mo stretchy="false">(</mml:mo> <mml:mrow> <mml:mo fence="false" stretchy="false">{</mml:mo> <mml:mn>001</mml:mn> <mml:mo fence="false" stretchy="false">}</mml:mo> <mml:mo fence="false" stretchy="false">⟨</mml:mo> <mml:mn>110</mml:mn> <mml:mo fence="false" stretchy="false">⟩</mml:mo> </mml:mrow> <mml:mo stretchy="false">)</mml:mo> </mml:math> texture. These distinct deformation states governed recrystallization during annealing at 1100, 1175, and 1250 °C for soaking times of 1, 2, and 3 h, with CR samples recrystallizing earlier, more uniformly, and to finer grain sizes than UR samples. Recrystallization textures largely inherited the rolling textures, with UR samples retaining a dominant <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mo fence="false" stretchy="false">{</mml:mo> <mml:mn>111</mml:mn> <mml:mo fence="false" stretchy="false">}</mml:mo> </mml:math> -fiber and CR samples showing progressive redistribution between rotated cube and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mo fence="false" stretchy="false">{</mml:mo> <mml:mn>111</mml:mn> <mml:mo fence="false" stretchy="false">}</mml:mo> </mml:math> -fiber components. Visco-Plastic Self-Consistent (VPSC) simulations accurately captured the true stress–strain response and texture evolution, identifying <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline" overflow="scroll"> <mml:mo fence="false" stretchy="false">{</mml:mo> <mml:mn>110</mml:mn> <mml:mo fence="false" stretchy="false">}</mml:mo> <mml:mo fence="false" stretchy="false">⟨</mml:mo> <mml:mn>111</mml:mn> <mml:mo fence="false" stretchy="false">⟩</mml:mo> </mml:math> slip as dominant. Samples annealed at 1250 °C displayed four-stage strain hardening, including an additional intermediate stage associated with increased work-hardening rate, enhancing uniform elongation. The key novelty of this work is the identification of strain-path-dependent recrystallization mechanisms and optimized annealing conditions for improved strength–ductility balance in Nb–10Hf–1Ti alloy sheets. Optimal strength–ductility synergy was achieved through strain-path-dependent annealing: UR samples at 1175 °C/2 h (YS∼279 MPa, UTS∼360 MPa, %El∼21) and CR samples at 1250 °C/1 h (YS∼248 MPa, UTS∼326 MPa, %El∼23) exhibited the best performance due to microstructure–texture optimization and enhanced recrystallization, respectively.