Subsurface crack initiation in high-cycle fatigue of Ti5Al2.5Sn extra-low interstitial alloy at liquid helium temperatureUmezawa, O., Nagai, K. and Ishikawa, K. Mater. Sci. Eng. A Nov. 1990 A129 (2), 217–221

1991 ◽  
Vol 13 (4) ◽  
pp. 361-361
Keyword(s):  
Crack Initiation ◽  
Liquid Helium ◽  
High Cycle Fatigue ◽  
Cycle Fatigue ◽  
Subsurface Crack

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.

Very High Cycle Fatigue Behavior and Thermographic Analysis of High Strength Steel

2010 ◽  
Vol 118-120 ◽  
pp. 948-951
Author(s):  
Chuang Shao ◽  
Claude Bathias ◽  
Danièle Wagner ◽  
Hua Tao
Keyword(s):  
Crack Initiation ◽  
High Strength Steel ◽  
High Cycle Fatigue ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
High Strength ◽  
Cycle Fatigue ◽  
Subsurface Crack ◽  
Very High Cycle Fatigue ◽  
Very High

Very high cycle fatigue behavior of high strength steel, were investigated using ultrasonic fatigue testing equipment at 20 kHz up to 109cycles. S-N curves at room temperature with different stress ratio (R=0.01 and R=0.1) was determined. The experimental results show that fatigue strength decrease with increasing number of cycles between 105 and 109. SEM examination of fracture surface reveals that fatigue damage was governed by the formation of cracks, and subsurface crack initiation was in the very long life range. The results shown that the portions of life attributed to subsurface crack initiation between 107 and 109 cycles are 99%.

scholarly journals Subsurface Crack Initiation in High Cycle Fatigue at Cryogenic Temperatures.

1991 ◽  
Vol 26 (4) ◽  
pp. 263-271 ◽  
Author(s):  
Osamu UMEZAWA ◽  
Kotobu NAGAI ◽  
Tetsumi YURI ◽  
Toshio OGATA ◽  
Keisuke ISHIKAWA
Keyword(s):  
Crack Initiation ◽  
High Cycle Fatigue ◽  
Cryogenic Temperatures ◽  
Cycle Fatigue ◽  
Subsurface Crack

scholarly journals Effect of Microstructure on the High-Cycle Fatigue Behavior of Ti(43-44)Al4Nb1Mo (TNM) Alloys

Metals ◽  
2019 ◽  
Vol 9 (10) ◽  
pp. 1043
Author(s):  
Bin Tang ◽  
Bin Zhu ◽  
Weiqing Bi ◽  
Yan Liu ◽  
Jinshan Li
Keyword(s):  
Crack Initiation ◽  
High Cycle Fatigue ◽  
Crack Nucleation ◽  
Fatigue Behavior ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Subsurface Crack ◽  
Tial Alloys ◽  
Fracture Morphologies

To investigate the high-cycle fatigue (HCF) behavior of TNM alloys, three different microstructures were designed and obtained by different heat treatments. Staircase tests and fatigue tests in a finite life-region were performed to evaluate the fatigue properties. Then, the fracture surfaces were analyzed to study the fracture behavior of TNM alloys with different microstructures. Results showed that the TNM alloys with duplex microstructure possesses the highest fatigue strength and fatigue life, followed by near lamellar TiAl alloys. HCF failure exhibited cleavage fracture morphologies, and multiple facets were generated in the crack initiation region of different TNM alloys. Two different crack initiation modes, subsurface crack nucleation and surface origin, were observed. Both crack initiation modes appeared in near lamellar alloys, while only subsurface crack initiation were obtained in the duplex (DP) alloy. It contributes to the high scatter of S-N data. The HCF failure of TNM alloys was dominated by crack nucleation rather than crack propagation. These findings could provide guidance for optimizing the microstructure and improving the HCF properties of TiAl alloys.

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