Influence of density and sintering temperature on high cycle fatigue behavior of FL4405 high strength PM steel

摘要

Density and sintering temperature effects on smooth axial and notched high cycle fatigue behavior were investigated with FL4405 low alloy PM high strength steel. Density levels of 7.0 and 7.4 g/cm3 and sintering temperatures of 1120 and 1315℃ were investigated. Previous research involving smooth axial and notched low cycle fatigue indicated that an increased density resulted in increased fatigue resistance. An increased sintering temperature also resulted in increased fatigue resistance, but to a lesser degree. This research showed that the increased density resulted in better fatigue resistance for the high cycle region as well. There was also a marginal improvement in high cycle fatigue resistance for the increased sintering temperature. The smooth axial and notched high cycle fatigue results mirror the influence on low cycle fatigue properties. The increased density resulted in a decrease in pore size and shape, while the increase in sintering temperature resulted in greater pore roundness. On a macroscopic level, all materials exhibited brittle fracture in both the fatigue crack growth region and the final fracture region but exhibited ductile behavior in these same regions on a microscopic level.