The Influence of Hydrogen on Hardening of Rapidly Quenched Ferritic/Martensitic Steel under High Temperature Exposure in Lithium

Abstract

This article presents experimental results on significant increase in the strength properties of the rapidly quenched ferritic/martensitic stainless steel obtained by consolidation of the rapidly quenched powder which was revealed during tension tests of the ring specimens of the nuclear fuel cladding tubes after exposure at 600°C in lithium with 0.05% hydrogen in comparison with exposure in pure lithium. The tension tests of the ring specimens of the nuclear fuel cladding tubes were carried out at room temperature. The microstructure and distribution of carbon, boron, carbide, and boride forming substitution alloying elements were investigated in detail after testing of rapidly quenched ferritic/martensitic stainless steel in pure lithium, lithium with 0.05% hydrogen and in argon environment. Significantly finer grains and formation of finely dispersed precipitates and pores in the ferritic/martensitic stainless steel after exposure in lithium with hydrogen addition are, obviously, the main reasons for the detected increase in the strength properties and decrease in plasticity.