SEDL / STP / STP1047-EB / STP24954S

Optimization of Reduced Activation Ferritic Steels

Abe, F
Senior researcher, Tsukuba Laboratories, National Research Institute for Metals, Tsukuba,

Noda, T
Head of the second laboratory, Tsukuba Laboratories, National Research Institute for Metals, Tsukuba,

Araki, H
Research assistant, Tsukuba Laboratories, National Research Institute for Metals, Tsukuba,

Okada, M
Director, Tsukuba Laboratories, National Research Institute for Metals, Tsukuba,

Pages: 10    Published: Jan 1990

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Abstract

In order to develop potential reduced-activation ferritic steels for fusion reactor structures, phase stability, toughness and creep rupture strength were investigated for Cr-W and Cr-V steels. Primary concern focused on 9% chromium steels because of their superior high temperature strength compared to low chromium steels. The Cr-W steels exhibited a similar precipitation behavior to carbides and intermetallic compound with conventional Cr-Mo steels while the Cr-V steels exhibited a quite different behavior. Creep rupture strength of 9Cr-2 steels increased but their toughness decreased with increasing the tungsten concentration. A martensitic 9Cr-lW steel showed an excellent toughness. On the other hand, both toughness and creep rupture strength of 9Cr-V steels were poor. The minor additions of vanadium, tantalum, and boron to the 9Cr-lW steel significantly increase creep rupture strength without the degradation of its excellent toughness.