Three-Point Bending Fatigue Test of TiAl6V4 Titanium Alloy at Room Temperature

Abstract

A polycrystalline alpha-beta TiAl6V4 alloy in the annealed condition was used for the three-point bending fatigue test at frequency f∼100 Hz. The static preload Fstat. = −15 kN and variable dynamic force Fdyn. = −7 kN to −13.5 kN were set as fatigue test loading parameters. The fatigue life S-N curve presented the stress amplitude σa as a function of a number of cycles to fracture Nf. A limiting number of cycles to run out of 2.0 × 107 cycles were chosen for the 3-point fatigue tests of rectangular specimens. In addition, the Smith diagram was used to predict the fatigue life. The alpha lamellae width has a significant influence on fatigue life. It is assumed that the increasing width of alpha lamellae decreases fatigue life. A comparison of fatigue results with given alpha lamellae width in our material to the results of other researchers was performed. The SEM fractography was performed with an accent to reveal the initiation sites of crack at low and high load stresses and mechanism of crack propagation for the fatigue part of fracture.

Fatigue Safety Coefficients for Ultra - High Region of Load Cycles

“…Figure 1 f a m v v =^h [12] were exhibited by the structural steels of higher strength, what is related to their higher sensitivity to both surface and internal defects (micro -impurity, microstructural heterogeneity, pores, grain size, inclusions). These statements are in accordance with the works of the authors [1][2][3][4][5][6][7]9]. It is clear from results (Figures 2 to 5, Tables 3 to 6) that Goodman and Soderberg methods are suitable methods (criteria) for evaluation of the fatigue safety of selected structural steels in the region of the high number of cycles.…”

“…after the so -called basic number N c = 10 7 load cycles in structural steels. The course of the dependence a v = f (N), including the step -wise or duplex curves with a "plato" is discussed [1][2][3][4][5][6][7]. High -graded steels of medium and high strengths are…”

Effect of geometric size deviation induced by machining on the vibration fatigue behavior of Ti‐6Al‐4V

“…The cleavage facets with river morphology are apparent along the crack advancing front. Belan et al 33 explained that the reliefs on the facets were created by the plastic deformation that occurs before the crack formation and growth. The same structures are observed on the right and left sides of the figure.…”

The influence of heat treatment on the nitriding layer on austenitic steel

“…Utilizing a Vibrophores Amsler 150 HFP Zwick/Roell fatigue machine, the fatigue tests involved preloading the test specimens at -13 kN, followed by cyclic loading at various amplitudes. The loading frequency was maintained at approximately 100 Hz [12,13]. The experimental specimens, free of V-notches, were cut from rectangular bars and sized at 55x10x10 mm (figure 1b).…”