Segmentation of twisted super clean wire in creep experiment

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The static torsion creep experiment with the OTEVA® 70 SC Super Clean steel wire reveals for some temperatures a peculiar behavior. In the creep experiment the applied torque moment was constant and the twist angle was acquired. Several experiments were performed for different constant torque and constant temperatures. For most single experiments the twist angle was a gradually increasing function of time. After the elastic unloading the surface of the wire in these cases was textured due to plastic deformation and demonstrates helical, screw-formed spirals with the constant slope over the length of the wire.

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However, for certain moments and elevated temperatures the abnormal behavior was observed. In the anomalous cases the wire demonstrated the sectional plastic behavior. The observed twist angle due plastic deformation along the wire was different along the wire length. The dependence of angles along the wire length demonstrates distinct segmented structure. In some segments the residual plastic deformation is considerably higher, as in other segments. The surface of the unloaded wire in these cases was textured differently and demonstrates broken screw-formed spirals with two distinct slopes over the length of the wire. During the active loading phase the jumps in the twist angle of the wire as the function of time were recorded. The number of jumps corresponds to the number of texture segments on the surface of the wire.

 

by Kobelev V., Mubea KG, Germany