The strength decreases in some steel wire ropes with increasing age. Also agency of heat causes a loss of strength. This loss is accorded with a drop-off in ductility and appears often in steel wire ropes that are made of high strength steel wire. A method should be found that determines the time to the drop-off in ductility. Tensile tests were conducted with notched steel wire specimen. The change in strength was examined in dependence of temperature and time. Vickers hardness testing was conducted in order to examine the behavior of strength along the diameter of the wire. An activation energy corresponding to the process, that causes the embrittlement, was determined by differential scanning calorimetry and by review of literature. A characteristic in the behavior of the notch strength of high strength wire was found that may correspond with the embrittlement. A temperature-time-curve was calculated analytically in conjunction with that characteristic.