Creep of CMSX-4 superalloy single crystals: Effects of rafting at high temperature
Creep of CMSX-4 superalloy single crystals: Effects of rafting at high temperature
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DOI：
10.1016/s1359-6454(99)00217-7
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发表时间：
1999-09-29
期刊：
影响因子：
9.4
通讯作者：
Rae, CMF
中科院分区：
文献类型：
--
作者：
Reed, RC;Matan, N;Rae, CMF
分析了(001)取向CMSX-4高温合金单晶在1000℃以上温度下的蠕变性能。伽玛结构的漂流发生得很快，例如对于 1150 摄氏度/100 兆帕的测试，漂流在前 10 小时内完成。在此阶段以及此后相当长的一段时间内，蠕变应变率随着应变的增加而降低，这意味着蠕变硬化效应不存在。当漂流动力学较慢时，温度较低。一旦达到 (0.7 +/- 0.3)% 的临界应变 epsilon*，蠕变应变就会急剧增加，并在几十小时内发生故障。事实证明，假设蠕变应变率和蠕变应变之间成比例的解释方法无法解释由于漂流而发生的蠕变硬化。提出了一种修改，该修改解释了当垂直伽马通道数量减少且细胞位错网络变得稳定时发生的 {111}{} 蠕变位错的滑动/爬升的阻碍。因此，必须将失效视为与蠕变空化有关，蠕变空化主要发生在铸件孔隙周围。需要强调的是，需要做更多的工作来量化各种蠕变损伤机制之间的相互作用。 (C) 1999 Acta Metallurgica Inc. 由 Elsevier Science Ltd 出版。保留所有权利。
The creep performance of (001)-orientated CMSX-4 superalloy single crystals at temperatures beyond 1000 degrees C is analysed. Rafting of the gamma structure occurs rapidly, e.g. for the 1150 degrees C/100 MPa tests rafting is completed within the first 10 h. At this stage and for a considerable time thereafter the creep strain rate decreases with increasing strain, implying a creep hardening effect which is absent at. lower temperatures when the kinetics of rafting is less rapid. Once a critical strain epsilon* of (0.7 +/- 0.3)% is reached, the creep strain increases dramatically and failure occurs within a few tens of hours. It is demonstrated that methods of interpretation which, assume a proportionality between the creep strain rate and creep strain, are unable to account for creep hardening which occurs as a consequence of rafting. A modification is proposed which accounts for the blocking of the glide/climb of {111}{} creep dislocations which occurs as the number of vertical gamma channels is reduced and cellular dislocation networks become stabilized. Consequently, failure must be taken to be associated with creep cavitation, which occurs predominantly around casting porosity. It is emphasized that more work is required to quantify the interaction between the various creep damage mechanisms. (C) 1999 Acta Metallurgica Inc. Published by Elsevier Science Ltd. All rights reserved.