We investigated how dwell fatigue loading accelerates the crack propagation in bi–modal Ti–6Al–4V alloy. A fatigue test was programmed to include
displacement holding for only one cycle at several ÿK. We found (1) crack tip strain evolved during the displacement holding, (2) the displacement holding
increased fatigue striation spacing, and (3) the strain increment during the displacement holding was linearly correlated with spacing of the displacement–holding–
extended striations. These facts indicate that the dwell loading assisted crack opening, which accelerated the crack propagation. Other analyses results and
discussion are also presented, in terms of crack propagation mode, crack closure, and dislocation structure.