Microstructure and crack sensitivity of electron beam welded titanium aluminide joints

【Abstract】 Microstructural characterization and crack formed mechanism during electron beam welding of titanium aluminide Ti-45Al-1.7Cr-1.7Nb were investigated. The results show that the welded microstructure exhibits columnar and dendritic structure. Microstructural constituents in the fusion zone are a massive gamma structure and some lamellar structure consists of alternating platelets of α₂ and γ. The major contributing factor of the susceptibility to solidstate cracking is thermally induced stress. The import role of the suppression of the α phase decomposition, the difference of α₂/γ phases thermal expansion coefficient and the lamellar spacing changes of lamellar structure with cooling rate all play effect on the crack forming mechanism.更多还原