Fatigue Strength Evaluation of Cu–Ni–Si Alloy Strips

This study investigates the mean stress effect on the fatigue strength and the mean stress effect criterion that best represents this effect in Cu–Ni–Si alloy strips using a new test method. Since the cyclic bending fatigue test based on the fatigue test standard for Japan Copper and Brass Association for understanding the fatigue characteristics of Cu–Ni–Si alloy strips needs many test times, a new test method to conduct effectively was examined and developed, and after confirming its validity, the mean stress effect criterion was identified using this method. The effect of surface electroplating on fatigue properties was also investigated. As a result, it was confirmed that the mean stress effect criterion on the fatigue strength of Cu–Si–Ni alloy strips was represented well by the elliptic line. The effect of surface electrolytic plating on fatigue properties was found to be strongly influenced by surface roughness rather than Young’s modulus or hardness of the constituent plating.