##### STP520

### Temperature Dependence of Fatigue Crack Propagation in an Al-2.6Mg Alloy

**Abstract**

Fatigue crack propagation has been studied in an Al-2.6Mg alloy between room temperature and 300 C. It is shown that the fatigue crack propagation rate is controlled by volume diffusion. The activation barrier for volume diffusion (*Q*^{0}) is lowered by the applied stress intensity range Δ*K* so that *Q*(Δ*K*) = *Q*^{0} - *C*^{1} log Δ*K*. The driving force for the process is inversely proportional to the square of the stress intensity range: *A*(Δ*K*) = *C*^{2} Δ*K*^{-2}. Fatigue crack propagation rate as a function of temperature and stress intensity range is given by daDN=C2ΔK-2exp-[Q0-C1logΔKRT] A special case of this equation is the well-known Paris equation.

**Keywords:**

fatigue (materials), crack propagation, aluminum alloys, stresses, thermal fatigue, cyclic strain, activation energy

**Author Information:**

Jeglic, F

*Graduate student, and professors, University of Waterloo, Waterloo, Ont.*

Niessen, P

*Graduate student, and professors, University of Waterloo, Waterloo, Ont.*

Burns, DJ

*Graduate student, and professors, University of Waterloo, Waterloo, Ont.*

**Committee/Subcommittee:** E08.05

**DOI:** 10.1520/STP38835S

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