Authors:
Christos Radis (1), Dennis Wawoczny (1), Markus Schneider (1), Robert Maassen (1)
1- GKN Sinter Metals Engineering GmbH, Radevormwald, Germany
Abstract:
The critical defect size a0 is that defect size a which can be tolerated by the material without a loss of strength. Its magnitude is of relevance for all Non-Destructive Testing methods because it defines the needed resolution limit. The critical defect size a0 depends on materials ductility (apparent hardness H) and on the loading ratio R. Four different sintered steels with a wide apparent hardness H range were chosen for the internal fatigue crack propagation campaign: AS 1000BMn + 2 % Cu + 0.6 % C, FD 4600A + 0.5 % C, FLD-49DH + 0.65 % C and AS 150 HP + 0.5 % C. Moreover, the sintered density ρ was varied between ρ=6.8 g/cm³ and ρ=7.2 g/cm³. Derived da/dN-ΔK curves were combined with existing s-N lines (“Woehler lines”) and the effect of the apparent hardness H on the critical defect size a0 was investigated.
DOI:
https://doi.org/10.59499/EP235760991