Abstract
Suspension springs are one of the automotive parts of which weight reduction is looked forward to and consequently demand is strong for higher strength materials. Therefore, the present joint study not only investigated and evaluated the currently available highstrength steel wires but also tried to recognize the problems involved and countermeasures required in increasing the strength of materials.
From the results of our study, it was clarified that higher strength of materials was effective in improving the sag resistance of springs. However, it was also indicated necessary to consider such processes as shot peening in the production of springs to ensure satisfactory durability.
Regarding the formability of steel wire which is likely to become an important issue in the future, a notch-bending test was introduced as one of the useful indexes to evaluate the formability of materials.
