Effect of acid pickling pretreatment on the microstructure and corrosion resistance of Ti-6Al-4V alloy

doi:10.12337/zgkqzzxzz.2025.02.009

Abstract

Abstract: Objective To evaluate the changes in the microstructure and corrosion resistance of Ti-6Al-4V alloy after different acid pickling pretreatments and to determine the optimal pickling method for titanium alloys used as implantable biomaterials. Methods The microstructure, hydrophilic properties, and corrosion resistance of machined Ti-6Al-4V alloy samples pickled with HF+H₂SO₄, HF+HNO₃, and HF solutions were analyzed using contact angle measurements, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and electrochemical tests. Results 1. Pickling rates varied among the three solutions: HF+H₂SO₄ (0.088 μm/s), HF+HNO₃ (0.064 μm/s), and HF (0.097 μm/s). 2. All groups exhibited characteristic α+β phase microstructures, with a higher proportion of β phase observed in the HF+HNO₃ and HF groups compared to the HF+H₂SO₄ group. The HF group also displayed hydride phases. Optical microscopy revealed the least pitting corrosion in the HF+HNO₃ group. 3. Corrosion resistance testing in simulated body fluids showed the following order of self-corrosion potential: control group > HF+HNO₃ group > HF+H₂SO₄ group > HF group. Conclusion HF+HNO₃ pickling produced Ti-6Al-4V alloy samples with smooth surfaces, a contact angle of 47.63°±2.40°, a weight loss rate of 1.11%±0.08%, and uniform removal of organic impurities and oxide films. The C/Ti and O/Ti ratios were reduced to 0.047±0.001 and 0.040±0.008, respectively. This treatment achieved higher corrosion resistance, with a self-corrosion potential of -0.676V. HF+HNO₃ is recommended as the preferred pickling solution for producing implantable Ti-6Al-4V alloys with superior corrosion resistance and a clean, uniform surface.

Key words: Ti-6Al-4V, Acid pickling, Simulated body fluids, Corrosion resistance, β phase

Zhao Yujia, Liu Qiqi, Qiu Lin, Hao Junjiang, Su Hanqi, Han Zekui, Wang Xinyu, Su Yucheng. Effect of acid pickling pretreatment on the microstructure and corrosion resistance of Ti-6Al-4V alloy[J]. Chinese Journal of Oral Implantology, 2025, 30(1): 47-53.

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