PSI - Issue 60

M. Suresh Kumar et al. / Procedia Structural Integrity 60 (2024) 433–443 Suresh Kumar et al.,/ Structural Integrity Procedia 00 (2023) 000 – 000

441

Fig.10. Delaminations at the crack initiation zone of fatigue fractures samples; (a) AR; (b) 200 HT; (c) 300 HT A recent study on 5083 H116 Al- Mg alloy highlights the role of β precipitates in the formation of delamination fractures (Brosi et al. (2010)). This study also reports delamination in the 5083 alloy when subjected to sensitization heat treatment that promo tes the formation of β precipitates along the grain boundary. Delamination was not reported in the non-sensitized alloy. In general, delamination fractures were observed in aluminium alloys containing elongated pancake shaped grains that possesses poor short transverse properties. In the current study, the alloy consists of elongated pan cake shaped grains and delamination was observed predominantly in the crack initiation region in all the conditions of the material, i.e., AR, 200 and 300 HT. DSC study and the static mechanical properties data suggested possible precipitation of β phase during exposure to tempe rature in the range 200 to 280°C precipitates. Thus, the delamination tendency was greater for the 200 HT sample and is attributed to the presence o f β precipitates. 4. Optimum creep forming temperatures Although 200 HT samples exhibited higher fatigue strength as compared to AR/300 HT samples, spring back was higher, and ductility in terms of % elongation was low in the material after exposure to 200°C. Hence, the results of the present study show that creep forming in the temperature range 160-280°C is not desired in view of the low ductility and high spring back. The alloy subjected to 300 HT condition not only produced zero spring back but also