Experimental and numerical investigations of the warm-prestressing (WPS) effect considering different load paths

The effect of warm prestressing has been investigated representative for th e core weld metal of the RPV Stade. Model experiments on CT specimens show a significant rise of effective fracture toughness K-eff after warm prestre ssing and the conservative WPS hypothesis,'no failure, if partial derivativ e k(l)/partial derivative t less than or equal to 0', is verified. Partial unloading and reheating show no influence on the effective fracture toughne ss K-eff. The magnitude of the WPS effect as a function of warm prestress l evel and temperature, path of unloading and cooling can be predicted using a modified Beremin model with temperature dependent parameters. It is shown that the Weibull stress is an appropriate crack tip loading parameter for decreasing load paths, (C) 2000 Elsevier Science S.A. All rights reserved.