Study On The Property Of Hot Forming Leading Edge And Anodization Process Of TB8 Titanium Alloy

Leading edge can protect the helicopter composite material blade, improve the anti-sand and anti-impact property. The property and surface treatment process of the leading edge has a direct influence on the persistence of cementation of composite blade, when the leading edge and composite blade was adhesive. TB8 titanium alloy offers high strength, small density, and good compatibility with composites, which is an ideal choice for leading edge material of composite blade.In this paper, the hot forming leading edge and anodization process of TB8 Titanium as the research object. The residual stress of the leading edge of the TB8 Titanium alloy and stainless steel was compared and analyzed. The TB8 titanium alloy leading edge was welded by laser welding, and anodized in the sodium tartrate electrolyte to improve the adhesive strength, besides the fatigue property of TB8 titanium alloy after anodized was investigated. Main work as follows. The residual stress of leading edge of TB8 titanium alloy and stainless steel was tested by small hole method, The maximum value of residual stress of TB8 titanium alloy leading edge was smaller than that of stainless steel leading edge, the uniformity of residual stress distribution of TB8 titanium alloy leading edge was better than that of 304 stainless steel leading edge. Laser beam welding of TB8 titanium alloy was tested at different conditions, it shows that TB8 titanium alloy had good welding performance. Then laser beam welding of TB8 titanium alloy leading edge was investigated to meet the actual needs of the size in application. The correlation between the adhesive strength, surface morphology, phase composition, roughness and wettability of the anodic oxide film of TB8 titanium alloy was investigated. The results showed that, an anodic oxide film about 1 ~ 4 ?m thick was formed on the surface after anodic oxide in the sodium tartrate electrolyte. The anodic oxide film with micro- and nano-porous rough structures has a high wettability, the anodic oxide film was composed by rutile TiO2 and anatase TiO2. The maximum shear strength(19.6 MPa) was obtained when the thickness of the anodic oxide film was about 3 ?m, which improved by 88.5%, and the water contact angle was 43.2°, decreased by 56.1%, the surface roughness was 2.32 ?m, improved by 157.8%. The fatigue fracture mechanism of TB8 titanium alloy sheet was investigated both unanodized and anodized in the film-forming agent of sodium tartrate. The results showed that, after anodic oxide treatment, the surface defects are eliminated effectively, the initiation and propagation rate of the crack source reduce, results in the fatigue striations more uniform and detailed. The fatigue strength of TB8 titanium alloy sheet after anodic oxide in the film-forming agent of sodium tartrate electrolyte increases by about 44%, comparing with the base metal in the fatigue life of 1×10~5 cycles.