对P92钢进行650 ℃, 0~5000 h时效实验, 采用萃取复型和电化学萃取2种方法分离时效样品中的沉淀相, 采用电感耦合等离子体发射光谱仪和EDS测定萃取物中合金元素的含量, 揭示Laves相析出引起的合金元素再分布规律. 利用Brinell硬度计测试P92钢时效过程中的硬度变化. 根据合金元素再分布特性, 建立基体溶质原子贫化损伤演化方程, 采用基于物理本质的CDM模型评价其析出对P92钢蠕变寿命的影响. 结果表明, 时效前P92钢中约86%的W和Mo固溶于基体, 剩余的14%分配在M₂₃C₆中. P92钢时效过程中由于Laves相析出发生合金元素的迁移, 其析出主要夺取基体中的W和Mo原子, 对时效前已析出的M₂₃C₆和MX相的成分影响很小. Laves相完全析出后, 基体中W和Mo的分配量均降至50%左右. Laves相的析出还消耗基体的一部分Cr, 使其分配量减少约3.6%. Laves相析出明显削弱溶质原子的固溶硬化作用, CDM计算表明, 其析出使P92钢在650 ℃, 100 MPa下的蠕变寿命缩短24%左右.

The P92 steel specimens were aged at 650 ℃ for 0~5000 h, and precipitates of the aged specimens were extracted from the matrix using carbon extraction replicas and potentiostatic electrolysis. The amount of alloy elements in extracted precipitates was determinded by inductively coupled plasma-atomic emission spectrometry (ICP-AES) and EDS, then the redistribution of alloying elements owing to Laves phase formation was analyzed. The hardness of aged specimens was taken using a Brinell hardness tester. The damage evolution equation owing to solute depletion was obtained from the redistribution characteristic of alloying elements and its influence on the creep life of P92 steel was evaluated based on the physical CDM model. The results are as follows. Before aging, about 86% contents of W and Mo in P92 steel are supersaturated in matrix and the remains are in M₂₃C₆ carbides. The removing of alloy elements take place due to the precipitation of Laves phase during aging. The formation of Laves phase consumes mainly W and Mo in matrix, and has little effect on the compositions of M₂₃C₆ cabides and MX carbonitrides precipitated before aging. The partition coefficients of these two elements supersaturated in matrix reduce up to 50% on the completion of Laves phase precipitation, and the Cr content in the matrix decreases about 3.6% because the formation of the Laves phase consumes Cr. The precipitation of Laves-phase contributes to the significant decreasing of solution hardening, causes the creep life of P92 steel reduction of about 24% at 650 ℃, 100 MPa.