Abstract
IT has been known for some time that iron undergoes several small changes at temperatures between that of the room and say, 350° C. These changes can be detected by variations in several physical properties and also appear to have some influence on the mechanical properties of the material. So far, however, no attempt has been made to investigate any effect of these change points on the fatigue limit of the metal. A paper by Mr. J. W. Cuthbertson, read before the September meeting of the Iron and Steel Institute, endeavours with considerable success to fill this gap in our knowledge. He has shown that the fatigue limit of a medium carbon steel rises as the temperature is increased to about 90° C. It then falls very rapidly, and at 120° C. or thereabouts, is less than at room temperature, to what degree, however, is still unsettled. As the temperature is still further increased the fatigue limit rises again very rapidly and at about 190° C. is some three tons per square inch higher than at room temperature. A second rapid drop then ensues, and a minimum occurs at about 220° C. followed by a further small rise. In an atmosphere of nitrogen the increase is progressive up to at any rate 350° C, but in air the fatigue limit begins to fall when the temperature exceeds about 300° C. The marked depression around 120° C. particularly is an observation of very great interest.
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Fatigue Limit of Medium Carbon Steel. Nature 131, 140 (1933). https://doi.org/10.1038/131140b0
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DOI: https://doi.org/10.1038/131140b0