TY - GEN
T1 - Effect of very high stress levels on the fatigue life of a TiAl based alloy
AU - Pilé, C.
AU - Retraint, D.
AU - François, M.
AU - Lu, J.
PY - 2005
Y1 - 2005
N2 - The aim of this work is to use ultrasonic shot peening, a mechanical surface treatment derived from conventional shot peening, in order to increase the fatigue life of TiAl alloys. The goal of this treatment is to generate compressive superficial residual stresses which are aimed to enhance fatigue crack initiation and growth resistance. For this purpose, different ultrasonic shot peening tests have been carried out on Ti-48Al-2Cr-2Nb samples in order to optimise treatment conditions. The first results reveal that it is possible to generate very high stress levels (≈1000 MPa) beneath the surface, far much higher than the tensile yield stress of the material which is in the range 350-600 MPa. Such a phenomenon was also observed in ultrasonic shot peened iron or stainless steel and seems to be associated to the creation of a new homogeneous and nanometric structure below the surface of the alloy [1, 2]. In the light of these encouraging results, the shot peening treatment was optimised in terms of residual stresses profile and surface quality. The influence of different parameters of shot peening like the treatment time, the shot diameter as well as the specimen-sonotrode distance were studied. S-N curves were realised on polished specimens as well as on shot peened samples in order to study the effect of the treatment on the fatigue life of this intermetallic alloy.
AB - The aim of this work is to use ultrasonic shot peening, a mechanical surface treatment derived from conventional shot peening, in order to increase the fatigue life of TiAl alloys. The goal of this treatment is to generate compressive superficial residual stresses which are aimed to enhance fatigue crack initiation and growth resistance. For this purpose, different ultrasonic shot peening tests have been carried out on Ti-48Al-2Cr-2Nb samples in order to optimise treatment conditions. The first results reveal that it is possible to generate very high stress levels (≈1000 MPa) beneath the surface, far much higher than the tensile yield stress of the material which is in the range 350-600 MPa. Such a phenomenon was also observed in ultrasonic shot peened iron or stainless steel and seems to be associated to the creation of a new homogeneous and nanometric structure below the surface of the alloy [1, 2]. In the light of these encouraging results, the shot peening treatment was optimised in terms of residual stresses profile and surface quality. The influence of different parameters of shot peening like the treatment time, the shot diameter as well as the specimen-sonotrode distance were studied. S-N curves were realised on polished specimens as well as on shot peened samples in order to study the effect of the treatment on the fatigue life of this intermetallic alloy.
KW - High cycle fatigue
KW - Hole drilling method
KW - Residual stress
KW - Titanium aluminide
KW - Ultrasonic shot peening
UR - https://www.scopus.com/pages/publications/35148823045
UR - https://www.scopus.com/record/pubmetrics.uri?eid=2-s2.0-35148823045&origin=recordpage
M3 - RGC 32 - Refereed conference paper (with host publication)
SN - 0878499695
SN - 9780878499694
VL - 490-491
T3 - Materials Science Forum
SP - 418
EP - 423
BT - Residual Stresses VII, ICRS 7
T2 - 7th International Conference on Residual Stresses, ICRS-7
Y2 - 14 June 2004 through 17 June 2004
ER -