Investigation on creep behavior of welded joint of advanced 9%Cr steels
Investigation on creep behavior of welded joint of advanced 9%Cr steels
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DOI：
10.1557/jmr.2014.366
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发表时间：
2015-01
影响因子：
2.7
通讯作者：
Donghai Meng;F. Lu;H. Cui;Yuming Ding;Xinhua Tang;X. Huo
中科院分区：
文献类型：
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作者：
Donghai Meng;F. Lu;H. Cui;Yuming Ding;Xinhua Tang;X. Huo
研究了先进9%Cr-1（BM 1）和先进9%Cr-2（BM 2）异种钢焊接接头的蠕变行为，并对其微观组织进行了表征。基于MATLAB的拟合，得到了描述初始蠕变阶段和稳态蠕变阶段的三维曲面。蠕变前后焊接接头显微组织的对比表明，BM 2侧热影响区（HAZ）中δ铁素体的分布对蠕变断裂强度起着重要作用。在538 °C不同应力载荷下进行蠕变试验后，在与BM 2相邻的过回火热影响区（OT-HAZ）发生断裂。显微硬度测试结果表明，与整个焊接接头相比，与BM 2相邻的OT-HAZ的硬度值最低。蠕变试验后，在试样的δ铁素体、碳化物和晶界处观察到大量的蠕变空洞。它们在热影响区集中长大，形成微裂纹，并在热影响区诱发断裂。蠕变后，晶界上出现了大量的第二相，随着蠕变时间的延长，热影响区的回火马氏体晶界逐渐模糊。
The creep behavior of advanced 9%Cr-1 (BM1) and advanced 9%Cr-2 (BM2) dissimilar welded joints was investigated in this paper, and also the microstructures were elaborately characterized. Based on the fitting with MATLAB, a 3-D curved surface describing the primary and steady-state creep stage was achieved. The comparison of the microstructures of the precreep and aftercreep welded joints shows that δ-ferrite distribution in the heat affected zone (HAZ) of BM2 side plays an important role in determining creep rupture strength. Fracture occurred at the overtempered heat affected zone (OT-HAZ) adjacent to BM2 after creep tests at 538 °C under different stress loads. Microhardness tests revealed that the OT-HAZ adjacent to BM2 has the lowest hardness value compared with the whole welded joint. Numerous creep voids occurring around δ-ferrite, carbides, and grain boundaries were observed on the specimen after creep test. They concentrated and grew up to microcracks, and then induced the fracture at OT-HAZ. Many second phases were also observed in the grain boundary after creep, and the tempered martensite boundaries in the HAZ gradually become obscure as the creep time increases.