The role of tungsten in the coarsening behaviour of M23C6 carbide in 9Cr-W steels at 600 A degrees C

Abstract

Tungsten is sometimes used as a solute in the so called 9Cr creep-resistant steels for use in the power generation industry, in part because of its ability to reduce the coarsening rate of M23C6 carbides. The mechanism by which it does so is not fully understood and indeed has been shown to be inconsistent with multicomponent coarsening theory, which predicts an opposite effect. This makes the role of tungsten to the coarsening behaviour of the carbide remain unsolved over decades. The work presented here is an attempt to show that the influence of tungsten can be reconciled with experiments, if kinetic study ignores the presence of Laves phase (Fe2W) in the system.