| Two different Electronic Beam Welded (EBW) joints of Ti60and TC17titanium alloy weretaken as the research object in this article. Theory and practice method were integrated in this researchto carry out the multiaxial fatigue test of the two different welded specimens and the study ofmultiaxial fatigue damage method.The uniaxial and multiaxial fatigue tests for the two different EBW joints under amplitudeunchanged multiaxial loads have been performed to establish the load-life(S-N) curve under differentloading modes. The influence of different loading modes and the fracture mode of two differenttitanium alloy EBW joints have been studied in this article. With the help of scanning electronmicroscope (SEM), Macro and micro observation were taken for the fracture morphology of twodifferent specimens. The extension of fatigue crack in two different kind of welded specimens wasoften to be like herringbone. The fracture morphology of Ti60welded specimens were cleavagefracture while TC17welded specimens were quasi-cleavage fracture.Based on critical plane method and the results of fatigue tests, mutiaxial fatigue methods of twodifferent EBW joints under multiaxial loading were studied in this article. Seven popular multiaxialfatigue damage criterions are examined with the obtained test data. In considering of the differencebetween loading model and the influence of material property, a modified definition for the factor s inthe KBM Criterion is presented, which can be effectively used in the multiaxial fatigue life evaluationof Ti60and TC17two different welded specimens. Findley and Itoh criterion have also been discussedin this paper. An in-depth study on the influence of different phases, non proportional loading andmaterial crystal structure to the multiaxial fatigue life of two different welded specimens have beendone. After introduced those corresponding correction methods, multiaxial fatigue life prediction oftwo different welded specimens achieved better results. |
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