| Abstract: | Effect of Surface Cold Working on Fatigue Strength and Cyclic Stress-Strain Behaviour of Normalized Plain Carbon Steels Ck 15 and Ck 45 under Compression-Tension and Rotating Bending Load Investigations on deep rolled specimens of normalized plain carbon steels showed that surface could working can improve the fatigue strength by about 15% in rotating bending tests and by about 5% in cyclic compression-tension tests. The better endurance properties are mainly caused by a reduced amplitude of plastic strain. From microscopical examinations of Ck 15 surfaces was deduced that crack initiation in deep rolled specimens resembles by far with that in specimens not surface treated. During fatigue tests the dislocation structure produced by deep rolling approached that developing in samples without cold worked surface. |
