Abstract
High cycle fatigue properties of high-pressure die-cast magnesium alloys AZ91 hp, AM60 hp, AE42 hp, AS21 hp and of similarly produced cast aluminium alloy AlSi9Cu3 have been investigated. Ultrasonic fatigue tests up to 10 9 cycles show mean fatigue limits of approx. 38-50 MPa (magnesium alloys) and 75 MPa (AlSi9Cu3) in the tested casting condition. Fatigue cracks initiated at porosity in 98.5% of the samples. Considering porosity as initial cracks, specimens fail, if critical stress intensity amplitude, K cr is exceeded. K cr of the magnesium alloys range from 0.85±0.05 to 1.05±0.05 MPa√m, and 1.85±0.10 MPa√m was found for AlSi9Cu3. Below K cr, fatigue cracks may initiate at porosity, however, do not propagate until failure. Using K cr, the statistical distribution of defects is linked to the fracture probability at different stress amplitudes.
| Original language | English |
|---|---|
| Pages (from-to) | 245-256 |
| Number of pages | 12 |
| Journal | International Journal of Fatigue |
| Volume | 25 |
| Issue number | 3 |
| DOIs | |
| Publication status | Published - Mar 2003 |
| Externally published | Yes |
Keywords
- Cast aluminium
- Cast magnesium
- Fatigue limit
- High-cycle fatigue
- Porosity