Crack growth behavior in dissimilar welded Ti based alloys under biaxial fatigue loading

•Biaxial fatigue crack growth tests are carried out for Ti17, Ti6242, and welded specimen.•FCGR is the highest for welded specimen and the lowest for Ti6242 for equibiaxial tension.•Fatigue crack is not inhibited by microstructure in Ti6242 alloy for macroscopic mode I + II.•SIF in mode I, II and III is derived from 3D FEA of relevant crack shape.•An equivalent SIF is proposed to account for mode mixity.