Duality of the fatigue behavior and failure mechanism in notched specimens of Ti-7Mo-3Nb-3Cr-3Al alloy

Giga-cycle fatigue behavior of notched specimens with stress concentration factor, Kt of 1.5, 2.0 and 2.5 for 0.65 mass% carbon matrix high speed steel, YXR3 with Rockwell C scale hardness number of 60.7 is investigated. The higher the stress concentration factor the lower the giga-cycle fatigue strength is. The emphasis is placed upon the subsurface crack initiation observed on all notched specimens. Crack initiation mode of high speed steel is discussed with respect to fracture surface morphology.

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Evaluation of Tensile Static, Dynamic, and Cyclic Fatigue Behavior for A Hiped Silicon Nitride at Elevated Temperatures

MRS Proceedings ◽

10.1557/proc-287-455 ◽

1992 ◽

Vol 287 ◽

Cited By ~ 1

Author(s):

Chih-Kuang Jack Lin ◽

Michael G. Jenkins ◽

Matitison K. Ferber

Keyword(s):

Silicon Nitride ◽

Cyclic Loading ◽

Crack Growth ◽

Failure Mechanism ◽

Fatigue Behavior ◽

Slow Crack Growth ◽

Cyclic Fatigue ◽

Creep Rupture ◽

Static Fatigue ◽

Dynamic Fatigue

ABSTRACTTensile fatigue behavior of a hot-isostatically-pressed (HIPed) silicon nitride was investigated over ranges of constant stresses, constant stress rates, and cyclic loading at 1150-1370°C. At 1150°C, static and dynamic fatigue failures were governed by a slow crack growth mechanism. Creep rupture was the dominant failure mechanism in static fatigue at 1260 and 1370°C. A transition of failure mechanism from slow crack growth to creep rupture appeared at stress rates ≤10−2 MPa/s for dynamic fatigue at 1260 and 1370°C. At 1 150-1370°C, cyclic loading appeared to be less damaging than static loading as cyclic fatigue specimens displayed greater failure times than static fatigue specimens under the same maximum stresses.

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High Cycle Fatigue Behavior of a Wrought Nickel-Base Superalloy GH4698

Materials Science Forum ◽

10.4028/www.scientific.net/msf.788.414 ◽

2014 ◽

Vol 788 ◽

pp. 414-420 ◽

Cited By ~ 1

Author(s):

Huan Wang ◽

Chao Yuan ◽

Jian Ting Guo ◽

Lan Zhang Zhou ◽

He Yong Qin

Keyword(s):

High Cycle Fatigue ◽

Fatigue Behavior ◽

Local Stress ◽

Cyclic Stress ◽

Nickel Base Superalloy ◽

Ambient Atmosphere ◽

Cycle Fatigue ◽

Notched Specimens ◽

Nickel Base ◽

Base Superalloy

Smooth and notched specimens of a wrought nickel-base superalloy GH4698 were subjected to high cycle fatigue (HCF) loading at room temperature and 650°C in ambient atmosphere. The experimental results show that the fatigue strength decreased with the increasing of temperature and cyclic stress, and fatigue limit of notched specimens was lower than that of smooth specimens. The fracture surface presents typical characteristics of fatigue fracture, where both stage I and stage II crack propagation can be found. For the smooth specimens, the single primary crack initiated on the surface or subsurface, while multiple primary cracks initiated on the surface for the notched specimens because of local stress concentration.

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