It is highly expectable that a coupling of strain rate and temperature also occurs under dynamic conditions, although its determination requires further tests not available for this work. However, the overall predominance of the temperature effects on the dynamic ones in affecting the necking inception is ascertained here independently of the possible further coupling above.

Failure strains under combined strain rate and temperature effects

Failure is a typically local phenomenon, so the local diameter-based true strains at fracture should be much more appropriate than the elongation-based engineering strains frequently adopted in the literature, which only reflect a global volume-averaged strain indicator.

Both types of fracture strains are reported in Table 4 for each test family (average of two or three test repetitions), together with the corresponding values of nominal strain rates and of estimated specimen temperatures at fracture. In the same table are reported also the effective / engineering strains ratio and the max postnecking true strain (Fail – Neck).

Table 4 Strain-related variables at fracture