Abstract
Fatigue crack growth in high strength aluminium alloy 7150 commercial plate material has been studied in both laboratory air and acidified aqueous salt solution. The aggressive aqueous environment enhanced fatigue crack growth rates by up to an order in magnitude compared to laboratory air. The enhancement in fatigue crack growth rate was accompanied by evidence of embrittlement in the crack path, involving both brittle intergranular and transgranular failure modes. Both the enhancement of fatigue crack growth rates and the extent of intergranular growth modes are dependent on cyclic frequency which, along with the absence of a similar frequency effect in a spray-formed version of the material with a significantly different grain structure, supports a mechanism of grain boundary hydrogen diffusion for intergranular corrosion fatigue crack growth. The convergence of corrosion fatigue crack growth rates at high ΔK in both spray-formed and conventional plate materials coincides with the operation of identical transgranular corrosion fatigue modes dependent on strain-controlled hydrogen diffusion ahead of the crack tip. © 1997 Acta Metallurgica Inc.
| Original language | English |
|---|---|
| Pages (from-to) | 3855-3870 |
| Number of pages | 16 |
| Journal | Acta Materialia |
| Volume | 45 |
| Issue number | 9 |
| DOIs | |
| Publication status | Published - Sept 1997 |
Keywords
- corrosion fatigue
- crack propagation
- crystal microstructure
- diffusion in solids
- embrittlement
- grain boundaries
- granular materials
- hydrogen
- metallographic microstructure
- solutions
- strain control
- strength of materials
- aluminum alloy 7150
- aluminum alloys