Fatigue test for welding specimen of electron beam welding and base metal specimen of TA19

which was made of titanium-based alloy often used in the blisk of civil aircraft engine

was performed at temperature 20

300

450℃. Fracture mechanism of welded joint was discussed by comparing the fracture face microstructures of welded metal with that of base metal. Then the stress-fatigue life (S-N) curves of both base metal and welded metal were created based on Basquin model in the fatigue life range of 104 to 106 cycles

showing that few test data of fatigue life can go beyond the two times error margin in the corresponding models

which indicates that the S-N curve obtained by test is reasonable. Through comparison of the S-N curves of welding specimen and base metal specimen

it can be seen that fatigue performance of welding specimen is higher than that of base metal specimen at temperature 20℃

while the differences of the fatigue performance between welding specimen and base metal specimen vary with the stress amplitude at temperature 300℃ and 450℃. Also

in above fatigue life range

the differences of calculated life prediction for welding specimen and base metal specimen are within the two times error margin. Thereby

the conclusion can be drawn that the fatigue performances of both are closer.