Effects of Setting-Treatment at Elevated Temperature on the Fatigue Strength and Fatigue Deformation of Coiled Spring

This paper presents the results of compressive fatigue and creep tests on piano wire coiled spring, setting-treated at elevated temperature conditions. The specimen is treated for 4min at a temperature of 250°C under the compressive load of 40kg, for this condition gives the material the highest values of proportional limit and spring constant.The results obtained are as follows;(1) The fatigue limit of setting-treated spring is about 14% higher than the conventional bluing-treated one.(2) The value of deformation limit is nearly constant for the value of τa/τm from 0.6 to 1.0, while it becomes higher as the value of τa/τm becomes lower.