dl08in,
The spring material specified by ASTM A401 has a very high yield and tensile strength, and limited elongation. When testing a straight section of the original wire, the yield strength will typically be in the range of 90-98% of the ultimate tensile strength, with elongation < 8%. However, is this really what you need? If you are trying to evaluate the performance/failure of an actual cold-coiled spring (helical compression, torsion, tension, etc.), then there are many processing variables that will affect this, including whether the parts are shot peened, what heat treatments are performed on the springs, etc.