Koichiro Nambu

Influence of Soft Particle Peening Treatment on Fatigue Strength of Aluminum Alloy A5052

Conventional shot peening using hard particles increases surface fatigue strength and surface roughness. An increase in the surface roughness contributes toward lowering the fatigue strength. To solve this problem, this study focused on the peening process using soft resin particles. The influence of peening with soft resin particles on the fatigue strength of aluminum alloy A5052 was investigated. Melamine with a particle size of 100 μm was used for soft resin particles. Alumina with the same particle size was used as a comparative material. By measuring the surface roughness, the surface roughness of alumina particles is demonstrated to be three times that of untreated specimen, whereas the surface roughness of melamine particles does not change. As a result of the hardness test, it was revealed that the hardness increases similarly to alumina particles even for melamine particles that are softer than A5052. Furthermore, when the treatment time was 60 s, the hardness was greater than when alumina particles were used. By using melamine particles, the measured residual stress value of the surface was higher than that of alumina particles. Through a fatigue test, the effect of the improvement to fatigue strength improvement effect was higher than that obtained from alumina particles when melamine particles were used. For this reason, improvement of the hardness and influence of surface roughness are conceivable. From these results, it is suggested that the peening process using soft resin particles is more useful than the conventional peening process.