PSI - Issue 13

Jürgen Bär / Procedia Structural Integrity 13 (2018) 947–952 Author name / Structural Integrity Procedia 00 (2018) 000 – 000

949

3

10 15 20 25 30 35 40 45 50 55

oxygen-free copper AA 6082-T651

D T max [K]

0 5

1

3

10

30

100

300

1000

crosshead speed [mm/min]

Fig. 2. Temperature increase measured in tensile tests on copper and AA6082 specimens.

To investigate the influence of the plasticity induced heating on the mechanical properties beside the tests in air tensile tests in water have been performed. In these tests, a higher heat dissipation is achieved, leading to a significantly reduced maximum temperature on the specimen surface as already shown by Lin and Wagoner (1987). For Copper and AA 6082 no differences in the tensile strength and the yield strength between the tests performed in air and water have been found. For the aluminum alloy 6082 the strain to failure was found to be independent of the crosshead speed and the environmental conditions (figure 3 left). In case of copper (figure 3 right) no differences in the strain to failure was found for crosshead speeds of 3 and 10 mm/min. For higher crosshead speeds a significant higher strain to failure was determined in the tests performed in water. The differences increase up to a crosshead speed of 100 mm/min, for higher crosshead speeds the differences between the values obtained in water and air are decreasing.

40

48

AA6082 air

Copper air

39

water

47

water

38

46

37

45

36

35

44

34

strain to failure A [%]

strain to failure A [%]

43

33

42

32

1

3

10

30

100

300

1000

10

30

100

300

crosshead speed [mm/min]

crosshead speed [mm/min]

Fig. 3. Change of the strain to failure measured in tensile tests in air and water for copper and AA6082.

Although the temperature increase in the tensile tests was nearly the same, copper shows a significant increase of the strain to failure in the tensile tests performed in water, whereas in the case of AA6082 no change in the strain to failure was found. Beside the temperature increase obviously the deformation behavior of the material is essential.