The specimens were subjected to quasi-static and load-controlled fatigue tests in an Instron 1272 tensile machine with a dynamic hydraulic load cell and hydraulic grips. For the quasi-static tests, a cross-head stroke rate of 0.4 mm/min was used. The longitudinal and transverse strains were registered on a computer with a Sandner A10-2.5 extensometer with a gage length of 10 mm and precision strain gages of type CEA-06-125UN-350 from Measurements Group, respectively. The closed loop fatigue tests consisted of a triangular wave form with a constant absolute strain rate of 10−2 s−1. The stress ratio was continually R=0.1 for various strain levels. By the strain level is here meant the initial (first cycle) peak strain which was calculated from the applied peak load. The chosen fatigue load rates did not result in any significant autogeneous heating. A thermocouple was occasionally applied on the specimen surface during testing, and never showed any temperature increase in excess of 2∘C for all specimens. Global isothermal testing conditions can therefore be assumed. All tests were performed at room temperature.