Creep Void Formation and Rupture Lifetime in Multiaxial Stress States
Creep Void Formation and Rupture Lifetime in Multiaxial Stress States
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DOI：
10.4028/www.scientific.net/kem.795.159
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发表时间：
2019-03
期刊：
影响因子：
--
通讯作者：
M. Sakane;H. Kobayashi;R. Ohki;Takamoto Itoh
中科院分区：
文献类型：
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作者：
M. Sakane;H. Kobayashi;R. Ohki;Takamoto Itoh
本文讨论了SUS 304不锈钢在高温下多轴应力状态下蠕变空洞的形成和断裂寿命。双轴和三轴拉伸蠕变试验分别使用十字形和立方体试样。这两种类型的标本设计，以实现均匀的等双轴和等三轴应力分布的有限元分析，在计部件。通过间歇双轴蠕变试验和中断三轴蠕变试验观察到晶界处的空洞形成。蠕变断裂寿命也得到了双轴和三轴蠕变试验。双轴应力增加空洞的形成，但在与冯米塞斯等效应力的相关性蠕变断裂寿命的影响不大。三轴应力也增加了空隙的形成，并大大减少蠕变断裂寿命的相关性与冯米塞斯等效应力。在等三轴应力条件下明显的空洞形成表明，冯米塞斯等效应力是不是一个合适的措施，以评估蠕变损伤发展在多轴应力状态。提出了一种新的等效应力来估算双轴和三轴应力状态下的蠕变断裂寿命。
This paper discusses creep void formation and rupture lifetimes in multiaxial stress states for a SUS 304 stainless steel at elevated temperatures. Biaxial and triaxial tension creep tests were performed using a cruciform and a cubic specimen, respectively. These two types of the specimens were designed to achieve uniform equi-biaxial and equi-triaxial stress distributions by a finite element analysis in the gage parts. Void formation at grain boundaries was observed by intermitting biaxial creep tests and by interrupting triaxial creep tests. Creep rupture lifetimes were also obtained in biaxial and triaxial creep tests. Biaxial stresses increase the void formation but give a little influence on a creep rupture lifetime in the correlation with von Mises equivalent stress. Triaxial stresses also increase the void formation and drastically reduce a creep rupture lifetime in the correlation with von Mises equivalent stress. Evident void formation in an equi-triaxial stress condition demonstrates that von Mises equivalent stress is not a suitable measure to evaluate creep damage development in multiaxial stress states. A new equivalent stress is proposed to evaluate creep rupture lifetimes in biaxial and triaxial stress states.