EFFECT OF SHOT PEENING DURATION ON FATIGUE LIFE OF GALVANIZED AND NON-GALVANIZED PEARLITIC HIGH STRENGTH HELICAL COMPRESSION SPRINGS

Abstract

In this study, the effect of shot peening duration on the fatigue life of galvanized and non-galvanized springs was investigated. As the shot peening duration increased, the fatigue life of the compression springs decreased due to several embrittlement mechanisms on the spring surface. The surface roughness almost linearly increased with increasing shot peening durations. The best fatigue life was obtained with shot peening durations of 10 and 20 min for non-galvanized and galvanized springs, respectively. The non-galvanized specimens exhibited better fatigue performance than galvanized springs. The main reason for the decrease in the fatigue performance of galvanized springs is hydrogen embrittlement behavior. Free hydrogen generated in the acid bath during the galvanizing process is entrapped between the surface and the zinc layer. As a result, the compression strain that reflects crack onset and propagation was adversely affected by hydrogen embrittlement behavior.