仕上面加工層に関する研究(第5報)

Abstract

The Effects of shot peening on the typical structures of such iron alloys as ferrite, pearlite, pearlite-cementite, martensite, pearlite-graphite, and martensite-carbides, were investigated. The above mentioned structures were obtained from 0.12% carbon steel (ferrite), 0.64% carbonsteel (pearlite), 0.99% carbon steel (pearlite and cementite), quenched 0.99 carbon steel (martensite), eutectic cast iron (pearlite and graphite), quenched and tempered highspeed steel (martensite-carbides) respectively. The test pieces were blasted with #20 cast iron shot under the compressed air pressure of 3.0 kg/cm2 for 3.0 minutes.For measuring the induced stresses in the surface layer and checking the hardening effect, the same method as described in the 4th report was adopted.The results were as follows :1. Among the three typical structures, the greatest effect of shot-peening is seen on martensite, then on pearlite, and the smallest effect on ferrite.2. The effect on martensite-carbide is smaller compared to that on martensite due to the existence of carbides.3. Pearlite-graphite has comparatively smaller surface compressive stress than pearlite due to the existence of graphite.