Effect of Temperature on Endurance Limit and Relaxation of Spring Materials

ENDURANCE limits and load losses at various temperatures from -75 F to 650 F for several spring materials are reported in this paper. The materials tested were in the form of helical springs, both shot peened and unpeened.

Some general observations made by the authors include:

1. 1.
   Shot-peened springs had higher endurance limits and greater relaxation than unpeened springs at -75 F and 75 F.
2. 2.
   As test temperatures rose above atmospheric, endurance limit of all unpeened springs tended to hold steady or increase somewhat, while that of shot-peened springs tended to decrease.
3. 3.
   Except for high-speed steel and stainless steel, chrome-silicon steel showed lowest load loss in both static and dynamic tests in the temperature range from atmospheric to 450 F.
4. 4.
   Both unpeened and shot-peened high-speed-steel springs showed high endurance limits at all test temperatures.
5. 5.
   Endurance limits at -75 F were similar to those at atmospheric temperature, but the amount of set was less, on the average.