Fatigue Strength of 0.45%　Carbon Steel Specimens Machined by Wire Electric Discharge

Recently, wire electric discharge machining method has been applied to the working and the cutting of parts as well as to die machining. Also in research of strength of materials, in processing of a minute specimen, a wire electric discharge machine will demonstrate great help. Therefore, the data concerning the relationship between the surface layer caused by wire electric discharge and fatigue strength are beginning to be required but we cannot find so many reports of the data concerning on this theme. So, plane bending fatigue tests were carried out on heat treated and annealed 0.45% carbon steel specimens machined by wire electric discharge. The fatigue strength of the heat treated 0.45% carbon steel processed by rough cutting with a wire electric discharge machine decreases approximately 44% from that of the unprocessed material. However, in the annealed 0.45% carbon steel, the decrease of the fatigue strength was only 10%.