Bending Fatigue of a High Performance PM Steel

摘要

Constant stress amplitude plane bending fatigue tests were made with a high performance PM steel based on a prealloyed 1.5 % Mo steel powder to which 4 % Ni and 2 % Cu were diffusion bonded. With sufficient amounts of carbon this material transforms - depending on the cooling rate - partially to bainite and martensite with retained austenite, pearlite and ferrite in the as-sintered condition. S-N curves based on at least 60 specimens in six stress levels each were established to determine endurance limits for smooth and notched geometries and different mean stresses within a range of densities. In total the results provide a rather comprehensive overview of the fatigue strength of this steel. Surprisingly the drop of endurable stress amplitude with increasing mean stress is very high in this case and statistically also the response to external notches is higher than usually.