Determination of J-Q Locus for Material of Reactor Pressure Vessel WWER 440 at Cleavage Fracture

Recently, series of 18 specimens of SEN(B) type and 18specimens of SEN(T) type were tested in Nuclear Research Institute .e.with the goal to quantify the effect of shallow crack (in-plane constraint) onfracture toughness for steel 15CH2MFA of WWER 440 reactor pressurevessel, for two types of loading: bending and tension. The tests wereperformed at temperature near reference temperature T0 determinedaccording to Master Curve concept, in the brittle-ductile transition region.Specimens contained deep or shallow cracks. Values of two fractureparameters J and Q were determined. Due to different characters of stressfields found for the two types of loading, the Q-stress parameter wasexamined in dependence on values of normalized distance r J 0 ƒÐ . Differentvalues of the normalized distance were examined, 2, 4, 6, 8 and 10. Basedon a reasonable criterion, the J-Q locus for WWER 440 RPV steel wassuggested, open for further discussion.