Volume 2, Issue 1 (January 1974)
Fatigue Behavior of Copper with Intermediate Surface Layer Removal
The effect of single and periodic intermediate surface layer removal on the fatigue behavior of oxygen-free, high-conductivity copper was studied in the life range of 105 to 2 × 106 cycles. The fatigue tests were conducted at room temperature, in tension-compression, under load control, and without mean load. The surface layer removal was accomplished by electropolishing. The variables of the test conditions were the engineering stress range, the average grain size, and the atmosphere (air and argon gas).
A single treatment of removing all the surface markings (caused by fatigue) during the life increased the subsequent fatigue life significantly. The largest increase in life was obtained after the largest period of precycling, which was about 80 percent of the standard life. The average plastic strain ranges after the polishing treatments were measured. The fatigue lives after polishing were strongly dependent upon the depth of the removed surface layer.
Periodic treatments to remove all the surface markings during the life also increased the fatigue life. Removal of all the surface markings after every 80 percent of the standard life increased the life by a factor of ten.