Grain refinement of Ti-6A1-4V alloy by cyclic hydrogenation and subsequent solution treatment

摘要

Ti-6A1-4V alloy (Ti-64) sheet specimens were subjected to a cyclic cathodic hydrogenation and subsequent solution treatment to see the effects of processing parameters on the grain refinement of Ti-64. Electrolytic hydrogenation was performed at 50 mA/cm~2 for 3 hrs in IN H_2SO_(4(aq)) by adding 0.1 g/L As_2O_3. The subsequent solution treatment was operated in a muffle furnace at 450°C for 80 min. The microstructural changes and the hydrogen uptake were evaluated qualitatively and quantitatively by utilizing X-Ray Diffractometry (XRD: X'Pert PRO MPD, PANalytical, Netherlands, 45 kV-40 mA), Metallographic Optical Microscopy (MOM) and elemental analysis (EA: elementar Vario EL-III), respectively. The hardness variation at the near surface was measured by utilizing Akashi Vickers hardness tester (MVK-H100). The original grain size (more than 2 mm) was refined to less than 20 μm and the surface hardness was elevated from 301.6 to 478.2 VHN.