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www.kiswire.com Practical comments Until not so long ago, the world was not familiar with the phenomenon, called strain aging, occurring in wire rope. As far as science shows us, much of cause of strain aging in wire rope could be due to the increase of tensile strengths of thewires used, during the past decades. Was a 1570 N/mm 2 tensile the benchmark until 1975, since then it became 1770 until the nineties, whereas the standard tensile strength today, is 1960 N/mm 2 . The regular tensile strength is 1960, however, we see that much of the wire ropes are required with high(er) breaking strengths than 1960 grades allow. Hence, tensile grades of 2060, 2160 and 2.300 have become quite common, meanwhile. The need of these high strength ropes (and tensiles) are the result of the industry’s wish to design small, light and ethical cranes, devices, and appliances. One of the main possible causes of susceptibility for strain aging, is a high carbon content in steel. A high breaking strength rope requires high carbon steel wires. Details of the metallurgical chemistry, relating to strain aging and high carbon content, is given in above text. KISWIRE, expert wire drawer Of the total volume of delivered wire, being one million tonnes per year, 140.000 tonnes of wire rope, 400.000 tonnes of high ductile, oil tempered wire for the car industry, is produced. Another 500.000 tonnes of wire is made for the tyre industry and the conductor industry. Out of the 400.000 tonnes of car industry wires, 200.000 tonnes high carbon, high ductile, non strain aging susceptible, wire is drawn. All wire rope is made to specific ordering. KISWIRE does not stock wire rope. Conclusion and recommendation Factors, which effect the susceptibility to Strain Aging of Wire Rope: 1. The chemical content of the steel used for the drawing of the wires (this chemical content impacts the mechanical characteristics of the wire) 2. Manufacturing process of steel. 3. One can minimize the risk of steel wire to strain age by choosing materials which are less susceptible to the phenomenon. 5. High(er) tensile strengths tend to be more susceptible to strain aging 6. Research and experience show that less than a promillage of all wire rope suffer from strain aging. Do not exaggerate the risks. 7. Average loss of strength by strain aging is under 5% 8. In the event, wire rope is stored longer than 12 months, one could break test the rope, prior to using it. Technical Data Sheet 9