Commercial aluminum alloy 5083 was processed using. the cryomilling synthesis approach to produce nanocrystalline powders. The powders were degassed at 450 degrees C, pre-heated and then quasi-isostatic forged to produce a thermally stable bulk ultrafine grain (UFG) material with average values of grain sizes ranging from 190 - 350 nm, dependent on processing conditions. In this paper, the high cycle fatigue behavior of the bulk UFG material over a range of maximum stress at a constant load ratio of 0.1 is presented and discussed. The specific influence of preheat temperature on cyclic fatigue life is elaborated upon and discussed. Three different preheat temperatures of 250 degrees C, 350 degrees C and 450 degrees C were chosen and used with the prime objective of controlling grain growth during forging. The final fracture behavior of the aluminum alloy is rationalized in light of secondary processing influences (i.e., pre-heat temperature) on microstructural development, maximum stress and resultant fatigue life.

In this research paper, the cyclic stress amplitude-controlled high cycle fatigue properties and fracture behavior of a titanium alloy are presented and discussed. The material chosen for this study is a Ti–Al–V–Fe–O2 alloy that is marketed under the trade name ATI 425™. This alloy was initially developed and put forth for use as a ballistic material but through the last few years it gained in stature for use in other areas due to a healthy combination of physical and mechanical properties. Test specimens were prepared, in conformance with the ASTM E-8 standard, from the as-received sheet stock, which was cold rolled and mill annealed, with the rolling direction both parallel (longitudinal) and perpendicular (transverse) to the length of the sheet. The test specimens were cyclically deformed at three different load ratios (R=0.1, R=0.3 and R=0.033) and the cycles-to-failure (Nf) was recorded. The fatigue fracture surfaces were examined in a scanning electron microscope to examine the macroscopic fracture mode, the intrinsic features on the fatigue fracture surface and the role of magnitude of applied stress–microstructural feature interactions in governing failure.

In this technical manuscript the cyclic stress amplitude controlled fatigue properties and fracture behavior of an emerging titanium alloy (referred to by its designation as ATI 425TM by the manufacturer) is presented and discussed. The alloy was provided as rod stock in the fully annealed condition. Test specimens of the as-received alloy were cyclically deformed under total stress amplitude control at two different stress ratios (R = 0.1 and R = 0.3) with the purpose of establishing the conjoint and mutually interactive influences of magnitude of cyclic stress, load ratio and intrinsic microstructural effects on cyclic fatigue life, final fracture behavior and viable mechanisms governing failure at the microscopic level. The high cycle fatigue resistance of this titanium alloy is described in terms of maximum stress, load ratio, and maximum elastic strain. The final fracture behavior of the alloy under cyclic loading conditions is discussed in light of the mutually interactive influences of intrinsic microstructural features, magnitude of cyclic stress, load ratio and resultant fatigue life.

In this technical paper, the microstructure, hardness, tensile deformation and final fracture behaviour of an emerging titanium alloy for performancecritical applications are presented and discussed. Both longitudinal and transverse test specimens were prepared from the as-provided sheet stock of the alloy and deformed in uniaxial tension. The yield strength and tensile strength of the alloy sheet in the transverse orientation was higher than the longitudinal orientation. The ductility of the test specimens, quantified in terms of reduction-in-cross-sectional area, was higher for the transverse specimen when compared to the longitudinal counterpart. The elongation-to-failure of the test specimens was identical in the two orientations of the sheet stock. The tensile fracture behaviour of the alloy was quantified by careful examination of the fracture surfaces in a scanning electron microscope. The intrinsic fracture features on the tensile fracture surface were discussed taking into consideration the nature of loading and contribution from intrinsic microstructural features.