AbstractLow cycle fatigue (LCF) behaviour as a function of test direction was studied for a quaternary Al–Li–Cu–Mg alloy. The analysis of the variation in fatigue life with plastic strain amplitude∆ɛp/2 or with average stress amplitude∆σ/2 or with plastic strain energy per cycle∆Wp, revealed bilinear power law relationships in all the test directions. The transition strain values in the Coffin–Manson plots were seen to match closely with those obtained in the cyclic stress response as well as with the cyclic stress–strain relationships of the alloy. The observed bilinear behaviour in these LCF properties was attributable to a change in deformation as well as to the deformation assisted fracture mode. The alloy revealed significant in plane anisotropy in the LCF properties. The observed anisotropy was found to result from the combined effects of strong crystallographic texture and grain fibering.MST/3016