Hot corrosion behavior of TC11 titanium alloy treated by laser shock processing

摘要

The aim of this research is to improve the hot corrosion resistance of TCl 1 titanium alloy by laser shock processing. Specimens were treated by laser shock processing on the whole surface. The hot corrosion resistance beneath Na_2SO_4 containing 20wt.% NaCl salt deposits at 650℃, 800℃ and 900℃ in air was investigated. The effects of LSP impacts on surface microstructure, residual stress, and microstructure after hot corrosion were investigated by transmission electron microscope, X-ray diffraction technology, and scanning electron microscope. Results show that laser shock processing can induce -295 MPa compressive residual stresses. The microstructure after LSP was characterized by a high amount of twins and highly tangled and dense dislocation arrangements. We even observed nano-crystallization. More protective oxidation films were remained on the surface of laser shocked specimens after hot corrosion, and it mainly consists of TiO_2, Al_2O_3, MoO_3, etc. The average corrosion rate of TCl1 titanium alloy treated by laser shock processing is more than 50% lower than that of the untreated alloy.