LOW-CYCLE FATIGUE BEHAVIOR OF GAMMA-BASED TI-48AL-2MN-2NB ALLOY PRODUCED BY CENTRIFUGAL SPRAY DEPOSITION

Push-pull low cycle fatigue behaviour has been studied at room tempera ture in a Ti-48Al-2Mn-2Nb alloy produced by centrifugal spray depositi on (CSD). The results have revealed that the available cyclic strain r anges are very narrow, which is Delta epsilon(t)/2 = 0.1-0.25 pct, and no cyclic hardening and softening behaviour has been observed during the fatigue process. Low cycle fatigue lifetime is very sensitive to t he cyclic strain amplitude, and decreases drastically with the increas ing of cyclic strain amplitude. Slip bands on the surface of specimens and substructures of different dislocation configurations, stacking f aults and twins inside the specimens have been evaluated and found to vary with the cyclic strain amplitude. Typical fracture surface charac teristics include the translamellar and interlamellar fracture, cleava ge-like failure and secondary cracks. Lamellar structure has a great e ffect on fatigue crack propagation. (C) 1998 Elsevier Science Ltd.