Influence of shot peening on the corrosion fatigue properties of a stainless steel for surgical implants

Abstract

AbstractFor some applications in surgical implants a rough surface is desired, since the jagged surface structure assists the adhesion of bone material or surface coatings. Some implants are peened with coarse and sharp edged peening media. In order to avoid a distinct loss of fatigue strength, spherical peening balls should be used. The present paper shows for stainless steel X2CrNiMo18‐15‐3 that the effect of surface roughening can be compensated by the effect of compressive residual stresses in the surface layer.However, the effect of surface flaws must not be ignored. For this reason, the shape and depth of surface flaws in shot peened surfaces has been examined and a classification of different types of surface flaws is presented.Fatigue tests in laboratory air and in physiological NaCl solution showed that there is a distinct influence of the depth and shape of surface flaws on the fatigue strength. The use of coarser peening balls and a subsequent electrolytic polishing treatment leads to an increase of fatigue strength.Furthermore, it is shown that shot peening may have a positive or negative effect on corrosion fatigue strength.