Effects of specimen size, initial crack acuity and test temperature on the master curve reference temperature

This paper reports the investigation of different variables viz. specimen size, specimen geometry, crack to length ratio a/W and the sharpness of the initial crack on the Master Curve reference temperature T0. The investigations were performed on 1T-C(T) and SE(B) specimens with different thicknesses. The specimens were machined from a sections of a RPV forged ring of steel 22 NiMoCr 3 7 of the not commissioned German pressurized water reactor Biblis C.
It was found that SE(B) specimens with different sizes (specimen thickness B=0.4T, 0.8T, 1.6T, 3.2T, fatigue pre-cracked to a/W=0.5 and 20% side-grooved) have comparable T0, but with a trend to lower T0 as the size decreases. T0 is dependent on specimen type. T0 of 0.4T-SE(B) specimens is 86.1°C, 15 K below the T0 = 70.1°C of 1T-C(T) specimens. Specimens with a/W=0.3 and a/W=0.5 crack length ratios yield comparable T0. The T0 of EDM notched specimens lies 41 to 54 K below the T0 of fatigue pre-cracked specimens. This effect is observed for different specimen sizes (0.4T and 0.8T), in both SE(B) and C(T) specimen types and with different crack length ratios (a/W=0.5 and 0.3). The paper presents a first evaluation of data obtained within a larger research project. A more detailed scientific analysis of the data will follow.