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Pulsating tension fatigue tests were conducted at 25°C, 150°C, and 250°C to investigate the effect of temperature on high cycle and very high cycle fatigue behavior of titanium alloy. The fatigue strength decreases with the increase of temperature, and the surface failure is more sensitive to temperature than interior failure. Afterwards, the fatigue fracture morphology, microstructure, and texture of titanium alloy were characterized. The results show that the fracture of larger αp phase with the maximum shear stress and higher strain concentration is responsible for the facet formation. The formation of facets leads to the interior failure at different temperatures. Finally, combining with the definition of interior crack growth rate, an assessment approach was proposed to predict the crack growth rate within the inhomogeneous microstructure area (IMA), which takes crack growth acceleration caused by the increase of temperature into consideration. [ABSTRACT FROM AUTHOR]

High cycle fatigue and very high cycle fatigue tests with pulsating tension for three surface‐carburized steels were performed to investigate interior failure behavior and life prediction method. As a result, all cracks with fine granular area and fisheye characteristics are induced from inclusions in matrix or in carburized layer. However, the later cracking morphology is smoother, which is due to the difference of plastic deformation and microstructure of the two regions. Based on estimation of threshold values for small and long crack growth, fatigue design curves are established. The maximum inclusion sizes of three carburizing steels were estimated by four statistical analysis methods. Combined with material microstructure characteristics and the critical plane theory, a failure‐based life prediction model is proposed by using fatigue indicator parameter, whose validity is verified based on good agreement between predicted and experimental ones. [ABSTRACT FROM AUTHOR]

• The crack-front plastic zone evolution of three aluminum alloys under the single overload with two overload ratios was traced using DIC technique. • Crack closure phenomenon was directly observed by using in-situ SEM testing. • The crack closure effect based on Paris-type bi-linear relation can well interpret the post-overload crack growth behavior. The dominant role of crack-front plasticity on crack growth retardation is verified. • A modified Willenborg model considering plastic zone shape effect and residual stress distribution was proposed. Fatigue crack growth behaviors of three aluminum alloys under single overload are investigated by in-situ optical microscopy testing and in-situ SEM testing. The results show that the shape effect of overload-induced plastic zone leads to a larger crack growth retardation range than that assumed in Willenborg model. Besides, the crack closure effect based on general form of Paris law cannot correlate the post-overload crack growth, but a bi-linear form fit the measured effective stress intensity factor behavior well. Moreover, the crack-front plasticity effected range can match the retardation extent. A modified Willenborg model is proposed to predict crack growth retardation. [ABSTRACT FROM AUTHOR]