EBSD-assisted fractography of subsurface crack initiation site in high cycle fatigue fracture of ultrasonic shot peened β titanium alloy

2016 ◽  
Vol 2016 (0) ◽  
pp. OS02-14
Author(s):  
Toshifumi KAKIUCHI ◽  
Yoshihiko UEMATSU ◽  
Tomomi TAKETANI ◽  
Minjie RONG ◽  
Kanehisa HATTORI
Keyword(s):  
Titanium Alloy ◽  
Crack Initiation ◽  
Fatigue Fracture ◽  
High Cycle Fatigue ◽  
Initiation Site ◽  
Cycle Fatigue ◽  
Subsurface Crack ◽  
Crack Initiation Site

High Cycle Fatigue Properties of Multi-Directionally Forged Commercial Purity Grade 2 Ti Plate

2018 ◽  
Vol 916 ◽  
pp. 166-169
Author(s):  
Ilhamdi ◽  
Toshifumi Kakiuchi ◽  
Hiromi Miura ◽  
Yoshihiko Uematsu
Keyword(s):  
Crack Initiation ◽  
High Cycle Fatigue ◽  
Pure Titanium ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Commercially Pure Titanium ◽  
Cycle Fatigue ◽  
Subsurface Crack ◽  
Initiation Mechanism ◽  
Fish Eye

Tension-tension fatigue tests were conducted using ultrafine-grained commercially pure Titanium (Ti) plates fabricated by multi-directional forging (MDFing). The MDFed pure Ti plates with the thickness of 1 mm were developed aiming at dental implant application. The fatigue properties of MDFed pure Ti plates were superior to those of the conventional rolled pure Ti plates. The higher fatigue strengths in MDFed plates could be attributed to the much finer grains evolved by MDFing. Fatigue crack initiated from specimen surface, when number of cycles to failure was shorter than 106 cycles. In the high cycle fatigue (HCF) region, however, subsurface crack initiation with typical fish-eye feature was recognized in the MDFed pure Ti plate in spite of the thin thickness. Fractographic analyses revealed that no inclusion existed at the center of fish-eye. The subsurface crack initiation mechanism could be related to the inhomogeneity of microstructure with some coarse grains in the inner part of the plate.

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