PSI - Issue 18

Sergey Uvarov et al. / Procedia Structural Integrity 18 (2019) 309–313 Author name / Structural Integrity Procedia 00 (2019) 000–000

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The diameter of the specimen was chosen by taking into account load cell limits and sensitivity of the Shimadzu AG-X 300 testing machine because serrations of the loading force during the testing of a smaller specimen could be filtered out as noise by the machine software. In order to avoid friction contact surfaces were lubricated by Castrol MS-3 grease.

Table 1. Chemical composition measured by electron microscope. Element Batch 1

Batch 2

Al Si

91.30

90.50

0.20 6.52 0.67 0.23

0.42 6.84 0.76 0.37

Mg Mn

Fe

Specimens were made of AMG6 alloy from two batches obtained from the different sources. The main difference between the batches is an amount of Si and Fe (Table 1). We are unable to reach the second critical point mentioned in D’Anna paper with the specimen from the second batch. Specimens from the second batch starts to fail at 60% of strain. Material under investigation has a big amount of Si-rich inclusions (fig. 2, Table. 2). In the work of Dierke (2007) where addition up to 5vol.% of Al2O3 particles showed hardly any influence on the PLC process so we expect the same behavior.

Fig. 2. Si-Al inclusions.

Table 2. Chemical composition of the inclusion and a rest of the material measured by electron microscope. Element Inclusion Rest Al 52.26 92.84 Si 43.90 - Mg 3.83 6.62

All specimens were annealed at 450 о С for 3 hours. Preliminary experiment on the specimen in as-received condition does not reveal any signs of the PLC effect. Tests were performed at 3 compression speeds: 1, 2 and 4 µm/s up to 90% of strain for the first batch and up to 60% for the Si-rich second batch. Typical loading curve for the specimen from the first batch is presented on fig. 3.