Rapid Solidification Of Aa8009 Heat-resistant Aluminum Alloy Electron Beam Welding Performance And Corrosion Study

Rapidly solidified high temperature aluminum alloy AA8009 (Al-8.9Fe-1.3V-1.7Si) is a kind of lightweight structure materials with high specific strength, high specific stiffness and excellent heat-resistance. It is able to be applied to the aerospace and aircraft industries instead of some of titanium alloys or steels which are usually used at the temperature range of 150~350℃. With the development of application, the welding technologies of AA8009 high temperature aluminum alloy are an important problem to be settled.To obtain good properties of the AA8009 alloy's welding joints, choose a suitable welding method and appropriate welding technologies to achieve excellent structures:a. "Recreate" a similar rapidly solidified microstructures in the weldfusion zoneb. "Retain" the base metal microstructure in the heat affected zonec. Eliminate or reduce welding defectsThis paper uses Electron Beam Welding method with high energy density and low energy input, room temperature tensile test, microhardness measurement and galvano-chemistry experiment, optical microscopy (OM), electronic microscopy analysis (SEM) to investigate the microstructures and properties(including mechanical properties and corrosion resistant properties) of the AA8009's welding joints. The results were analyzed and discussed theoretically and several conclusions can be summarized as follows:1) With the cooling rate increasing in the weld fusion zone, the weld microstructures are bettered, welding joints' tensile strengths and elongation percentages increase (including vertical and along weld direction) and the "weak-link" change from fusion boundary region to heat affected zone.2) Welding joints' microhardness curves are symmetrical with respect to weld center. With the cooling rate increasing in the weld, welding joints' microhardness increase.3) Main defects of AA8009 EB welds are porosities and cracks.4) Galvano-chemistry experiments show that AA8009 base metal's corrosion resistant property is better than EB welding joints'. With the cooling rate increasing in the weld, the weld corrosion resisting properties increase.