Crack Paths 2012

b

a

c

Figure 8. Asbhy maps for 99%Al with superimposed the experimental failure stress (a)

showing that data fall in ductile and transgranulare fracture type. S E Mfractographs of

samples deformed at 300°C 10-3s-1(b) and 10-5 s-1(c) characterized by dimples and

microvoid.

C O N C L U S I O N S

The main conclusions of this stdy are reported in the following:

1)During tensile test at 250°C, the significant reduction of the stress by reducing the

strain rate is due to precipitation /coarsening of Zn-Mgparticles

2) Precipitated Zn-Mg particles not are active in crack nucleation in fact at 250°C

cavitation remains almost constant as strain rate decreases. The role of nucleation point

of the cavity seems to be related to the constituent particles and segregation as shown by

strong reduction of cavitation in the sample solutionized at 490°C-2h before tensile

deformation at 250°c and 400°C

3) In the investigated range of experimental conditions, the cavity growth is mainly

driven by plastic straining and the fracture type is transgranular ductile.

R E F E R E N C E S

1. H.J. McQueen, P. Leo and E. Cerri; AluminumAlloys: Fabrication, Characterization

and Applications, : Weimin Yin, Subodh Das, Zhengdong Long Eds: T M SU S A2009

pp.37-44

2. J.E. Hatch,ed. Aluminum, Properties, Physical Metallurgy, ASM,Metals Park, Oh,

1984

3. H.J.McQueen, O.C. Celliers, Canadian Metal. Quart. 36 (1997), 73-86

1129