Effect of thermal aging on the microstructure and mechanical properties of7-11 CrW steels

The aim of this paper is to present the evolution of the microstructure, te nsile and impact properties of Fe-7.5/ 11CrWVTa reduced activation martensi tic CRAM) steels after thermal aging performed at relevant temperatures for fusion applications (250-550 degreesC). The materials investigated are exp erimental alloys with different contents of Cr (7.5-11%), Ta (0-0.1%), W (0 .8-3%) and interstitial elements, such as carbon (0.09-0.17%) and nitrogen (0.004-0.045%). Thermal aging was performed for up to 13 500 h on steels wi th different metallurgical conditions: normalized and tempered (N&T) and no rmalized and tempered + 10% cold worked (N&T-CW). The characterization of t he microstructure was performed by transmission electron microscopy (TEM) a nd by small angle neutron scattering (SANS). The evolution of tensile prope rties depends essentially on the initial metallurgical conditions, whereas the modification of impact properties is mainly defined by the chemical com position that governs the occurrence of alpha prime and Laves phase precipi tation. (C) 2000 Elsevier Science B.V. All rights reserved.