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<p>Recycling production scraps offers an innovative pathway to enhance corporate cost-efficiency in industrial production. To achieve this, the study sequentially employs electron beam cold hearth melting (EBCHM) melting, forging, rolling, solution treatment, and aging to investigate the microstructure and corrosion behavior of scrap-rolled Ti–6Al–4&#xa0;V alloy processed through these manufacturing stages. At 800&#xa0;°C solution temperature, the sample exhibited equiaxed <i>α</i> grains. Upon increasing to 850&#xa0;°C, martensitic <i>α</i>′ phase initiated, forming a bimodal microstructure comprising original equiaxed <i>α</i> phase and high-density <i>α</i>′/<i>β</i> lamellar regions. Progressive temperature elevation reduced equiaxed <i>α</i> phase volume fraction while amplifying lamellar structure proportion. Post-aging treatment yielded mixed-phase architecture featuring equiaxed <i>α</i> and secondary <i>α</i> precipitates within <i>β</i> matrix, with coarsening secondary <i>α</i> phases under elevated aging temperatures. Electrochemical tests demonstrated contrasting corrosion behaviors: In 3.5&#xa0;wt% NaCl, all alloys exhibited spontaneous passivation, while in 5&#xa0;M HCl, active–passive transitions emerged with cathodic hydrogen evolution reaction dominance. Electrochemical impedance spectroscopy with equivalent circuit fitting verified a dense oxide film (single-time constant) in NaCl versus dual time constants in HCl, corresponding to porous films with compromised protection. Surface morphology analysis and atomic force microscopy confirmed the <i>α</i>(<i>α</i>′) phase as the preferentially dissolved constituent. Electrochemical and static immersion tests demonstrated opposing trends: Solution-treated alloys exhibited improved corrosion resistance with elevated solution treatment temperatures, while solution-aged alloys showed reduced resistance at higher aging temperatures, correlated with <i>α</i> (<i>α</i>′) phase thickness modulation. Electron work function calculations further substantiated this observations.</p>

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Optimizing the microstructural configuration and augmenting corrosion resistance of scrap-rolled Ti–6Al–4 V alloy bars through solution coupled with aging processes

  • 期刊论文

  • 发表日期：

    2026年1月5日

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  • Peng Shao,
  • Ju Huang,
  • Siyuan Zhai,
  • Kun Liu,
  • Shuqi Deng,
  • Han Xiao

摘要

Recycling production scraps offers an innovative pathway to enhance corporate cost-efficiency in industrial production. To achieve this, the study sequentially employs electron beam cold hearth melting (EBCHM) melting, forging, rolling, solution treatment, and aging to investigate the microstructure and corrosion behavior of scrap-rolled Ti–6Al–4 V alloy processed through these manufacturing stages. At 800 °C solution temperature, the sample exhibited equiaxed α grains. Upon increasing to 850 °C, martensitic α′ phase initiated, forming a bimodal microstructure comprising original equiaxed α phase and high-density α′/β lamellar regions. Progressive temperature elevation reduced equiaxed α phase volume fraction while amplifying lamellar structure proportion. Post-aging treatment yielded mixed-phase architecture featuring equiaxed α and secondary α precipitates within β matrix, with coarsening secondary α phases under elevated aging temperatures. Electrochemical tests demonstrated contrasting corrosion behaviors: In 3.5 wt% NaCl, all alloys exhibited spontaneous passivation, while in 5 M HCl, active–passive transitions emerged with cathodic hydrogen evolution reaction dominance. Electrochemical impedance spectroscopy with equivalent circuit fitting verified a dense oxide film (single-time constant) in NaCl versus dual time constants in HCl, corresponding to porous films with compromised protection. Surface morphology analysis and atomic force microscopy confirmed the α(α′) phase as the preferentially dissolved constituent. Electrochemical and static immersion tests demonstrated opposing trends: Solution-treated alloys exhibited improved corrosion resistance with elevated solution treatment temperatures, while solution-aged alloys showed reduced resistance at higher aging temperatures, correlated with α (α′) phase thickness modulation. Electron work function calculations further substantiated this observations.