At Bosch Transmission Technology B.V. high strength maraging steels are applied for the mass production of pushbelts for CVT applications. To secure the pushbelt behaviour in the Very High Cycle Fatigue area (>10 million load cycles) the VHCF properties of four 18Ni maraging steels are investigated in cooperation with BOKU, Institute of Physics and Materials Science (Vienna). Ultrasonic fatigue tests are performed on thin sheets with gas nitrided surfaces. Traditional maraging steel is compared to Titanium-free maraging steels with different Cobalt contents. The influence of different types of non-metallic inclusions on fatigue crack initiation and VHCF strength will be presented.
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