The strength of 9Cr steels, which is controlled by chemical composition and microstructure, evolves significantly under high temperature loading. This paper presents a temperature-independent, physically-based model for evolving yield strength, including the interdependent effects of dislocations, solutes, precipitates and grain boundaries. The key roles of solute and precipitate strengthening in 9Cr steels are successfully demonstrated. The measured significant beneficial effect of up to 3 wt% tungsten on solute strengthening, and hence, yield strength are successfully predicted. The new model demonstrates that the reported strength reduction in 9Cr-3W alloys under thermal aging can be primarily attributed to Laves phase formation and associated depletion of tungsten solutes, consistent with microstructural observations.

受化学成分和微观结构控制的9Cr钢的强度在高温载荷下会显着变化。本文提出了一种基于温度的，基于物理的屈服强度演化模型，其中包括位错，溶质，析出物和晶界的相互依赖效应。成功地证明了9Cr钢中溶质和沉淀强化的关键作用。测得高达3 wt％的钨对溶质强化的测量的显着有益效果，因此成功地预测了屈服强度。新模型表明，据报道，9Cr-3W合金在热时效下的强度降低主要归因于Laves相形成以及相关的钨溶质损耗，这与微观结构观察一致。