Topic
Fatigue limit
About: Fatigue limit is a research topic. Over the lifetime, 20489 publications have been published within this topic receiving 305744 citations. The topic is also known as: endurance limit & fatigue strength.
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TL;DR: In this article, the size and composition of inclusions in spring steels (Heats A and D1) and one valve spring steel (Heat F) with tensile strength, σ B, of 1720, 1725 and 1764 MPa, respectively, were controlled.
Abstract: Fatigue tests up to 10 8 cycles were carried out for two spring steels (Heats A and D1) and one valve spring steel (Heat F) with tensile strength, σ B , of 1720, 1725 and 1764 MPa, respectively. The size and composition of inclusions in Heats Dl and F were controlled. The surface-type fracture occurred at shorter lives below 10 6 cycles, while the fish-eye-type fracture occurred at longer lives. The fatigue limit, σ W , at 10 8 cycles was 640 MPa for Heats A and D1 and 700 MPa for Heat F. Al 2 O 3 inclusions for Heat A and both TiN inclusions and matrix cracks, i.e. internal facets, for Heat F were observed at the fish-eye-type fracture sites, while only matrix cracks were observed for Heat Dl. ODA, i.e. optically dark area, which is considered to be related to hydrogen effects, were formed around Al 2 O 3 and TiN inclusions. Fatigue tests were also conducted after specimens were heated up to 573 K in high vacuum of 2 × 10 -6 Pa. The heat treatment eliminated matrix cracks for Heat D1 and the fatigue limit at 108 cycles recovered to the estimated value of 920 MPa from the equation ω w = 0.53 ω B for the surface fracture. These results suggest that inclusions control and hydrogen influence the gigacycle fatigue properties for these high strength steels. In addition, it is expected that the creation of a martensite structure with a high resistance to hydrogen effects in the inclusion-controlled steel could achieve the higher fatigue limit estimated for the surface-type fracture.
77 citations
TL;DR: In this article, a lock-in thermographic technique was applied for analysis of stress concentration zones to specimens, made of the same steel, with central flat bottom hole, achieving good predictions.
76 citations
TL;DR: In this paper, the authors examined the effect of artificial aging on the fatigue crack propagation of 2xxx-series aluminum alloys and found that the most resistance to fatigue crack growth correlates with the presence of accelerated solute clusters and absence of distinct precipitates.
76 citations
TL;DR: In this paper, the authors examined the influence of austempering heat treatments and the resultant microstructure of alloyed nodular ductile cast iron on the fatigue crack growth rate, fatigue threshold, and high-cycle fatigue strength of the material.
76 citations
TL;DR: In this paper, the authors investigated the fatigue behavior of first-year sea ice that subjected in situ cantilever beams to repeated bending with zero mean stress and found that an endurance limit exists for sea ice, and that it is approximately 60% of the flexural strength.
Abstract: The manner in which sea ice breaks up determines its floe-size distribution This, together with any redistribution due to ocean currents or winds, alters the fluxes between the atmosphere and the underlying ocean Many materials fail at stresses well below their flexural strength when subject to repeated bending, such processes being termed fatigue in some materials a stress exists below which the material will maintain its integrity even if subjected to an infinite number of load cycles This stress is termed the endurance limit We report a scries of field experiments to investigate the fatigue behaviour of first-year sea ice that subjected in situ cantilever beams to repeated bending with zero mean stress These tests suggest that an endurance limit exists for sea ice, and that it is approximately 60% of the flexural strength Using theory and data from wave experiments performed in similar conditions to the fatigue experiments, estimates are made of the conditions under which wave-induced break-up occurs These indicate that fatigue may be a neglected ingredient of sea-ice failure due to wave-induced motion
76 citations