1. Steel Research Center, National Institute for Materials Science,1-2-1 Sengen, Tsukuba 305-0047, Japan
2. Materials Information Technology Station, National Institute for Materials Science,1-2-1 Sengen, Tsukuba 305-0047, Japan

Correspondence to: Fujio Abe¹ Email: ABE.Fujio@nims.go.jp

Abstract

Creep is a time-dependent mechanism of plastic deformation, which takes place in a range of materials under low stress—that is, under stresses lower than the yield stress¹. Metals and alloys can be designed to withstand creep at high temperatures, usually by a process called dispersion strengthening², in which fine particles are evenly distributed throughout the matrix. For example, high-temperature creep-resistant ferritic steels achieve optimal creep strength (at 923 K) through the dispersion of yttrium oxide nanoparticles³. However, the oxide particles are introduced by complicated mechanical alloying techniques and, as a result, the production of large-scale industrial components is economically unfeasible. Here we report the production of a 9 per cent Cr martensitic steel dispersed with nanometre-scale carbonitride particles using conventional processing techniques. At 923 K, our dispersion-strengthened material exhibits a time-to-rupture that is increased by two orders of magnitude relative to the current strongest creep-resistant steels⁴. This improvement in creep resistance is attributed to a mechanism of boundary pinning by the thermally stable carbonitride precipitates. The material also demonstrates enough fracture toughness. Our results should lead to improved grades of creep-resistant steels and to the economical manufacture of large-scale steel components for high-temperature applications.