Microstructural degradation of Gr.91 steel during creep under low stress
Microstructural degradation of Gr.91 steel during creep under low stress
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DOI：
10.1016/j.msea.2011.03.073
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发表时间：
2011-06-25
期刊：
影响因子：
6.4
通讯作者：
Kimura, K.
中科院分区：
文献类型：
--
作者：
Sawada, K.;Kushima, H.;Kimura, K.
在600 ℃下70 MPa蠕变过程中的显微组织变化进行了研究的情况下中断的Gr.91钢样品考虑到位错结构和Z相的形成。在研究中考虑的每个温度下，蠕变寿命随着施加应力的降低而单调增加。然而，长期蠕变寿命短于600 ℃和650 ℃下的短期蠕变数据，这意味着过早失效。亚晶尺寸逐渐增加，在蠕变到70,000小时，然后发生快速的亚晶粗化。在50，000 h和70，000 h后，在原奥氏体晶界（PAGB）附近发生了亚晶组织的优先回复。蠕变断裂后，在每个样品的整个区域上观察到亚晶回复。在蠕变后30，000小时内，Z相形成清晰可见。由于Z相的形成，MX颗粒的数密度在30，000 h后逐渐降低。蠕变断裂后，MX颗粒的数量密度几乎与Z相颗粒的数量密度相同。在蠕变过程中，Z相的V含量逐渐增加，但Nb含量下降。在Z相的化学组成的变化发生在一个较长的时间后，在Gr.91钢比在12 Cr钢。(C)2011 Elsevier B. V.保留所有权利。
Microstructural changes during creep at 600 degrees C under 70 MPa were investigated in the case of interrupted Gr.91 steel samples by taking into account the dislocation structure and Z-phase formation. The creep life monotonically increased with a decrease in the applied stress at each temperature considered in the study. However, the long-term creep life was shorter than that determined from the short-term creep data at 600 degrees C and 650 degrees C, meaning premature failure. The subgrain size gradually increased during creep up to 70,000 h, after which rapid subgrain coarsening occurred. Preferential recovery of the subgrain structure occurred around the prior-austenite grain boundary (PAGB) after 50,000 h and 70,000 h. After creep rupture, subgrain recovery was observed over the entire area of each sample. Z-phase formation was clearly visible for 30,000 h after creep. The number density of the MX particles gradually decreased after 30,000 h because of Z-phase formation. After creep rupture, the number density of the MX particles was almost the same as that of the Z-phase particles. During creep, the V content of the Z-phase gradually increased but the Nb content decreased. Changes in the chemical composition of the Z-phase occurred after a longer time in Gr.91 steel than in 12Cr steel. (C) 2011 Elsevier B.V. All rights reserved.