Nobuyuki Miyamoto

Very high cycle fatigue behavior of high strength steels

Life extension of engineering plants and high-speed operation of engineering machines are required in various fields. In these situations, conventional fatigue strength determined as the strength for 107 cycles is not sufficient. It is necessary to adopt the data up to giga cycle regime for design and maintenance.

High Cycle Fatigue Strength of Spring Steel with Small Scratches

When the compression coil springs are subjected to high cyclic stress, fatigue crack sometimes initiates and propagates from small scratch or defect produced in the manufacturing process. However, there are a limited number of studies on the fatigue behavior of high-strength spring steel in the presence of small scratch. In this study, the fatigue tests were conducted to examine the uniaxial fatigue behavior of a high-strength spring steel (JIS G 3561, SWOSC-V) in the presence of small circumferential notches. Based on \(\sqrt{area}\) parameter model, the sensitivity of hard steels, including a high-strength spring steel, to small scratches was qualitatively and quantitatively examined.