Chromium-vanadium is the most popular alloy steel for springs that are required to withstand a large number of operating cycles. It is medium carbon steel with chromium and vanadium added to increase its hardness and tensile strength. The pre-tempered material is best for valve or gun springs. Springs can be used at extremely high stresses in applications where they will also be subject to extreme shock and impact loading. For springs of high endurance, the alloy is usually used at a hardness of Rockwell C44-49. Where extreme stresses and short life are expected, the hardness is increased to Rockwell C50-53.
In sizes 0.375″ and under, chromium-vanadium alloy springs have no higher endurance limits than plain carbon steels of valve spring quality. However, the alloy springs have less tendency to relax at temperatures as high as 400°F and satisfactory operation can be obtained at temperatures up to 750°F. when loads are not severe, when the stress range is narrow, or when stress changes are infrequent.
Recommendations for heat treatment: Immediately after coiling, the springs should be stress relieved at about 400°C. (750°F.) for 30 minutes. After shot peening, the springs should be stress relieved at about 250°C. (480°F.) for 30 minutes.
Gibbs Interwire oil tempered commercial quality chromium-vanadium meets ASTM-A-231 specification. Wire is available in size ranges from 0.092″ – 0.625″