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Creep-ratchetting of Heat Resisting Steels at Elevated Temperature in Multiaxial Stress State

高温多轴应力状态下耐热钢的蠕变棘轮

基本信息

批准号：
62550077
负责人：
YOSHIDA Fusahito
金额：
$ 1.02万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1988
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-62550077/
关键词：
2 1 4Cr-1Mo steel SUS304 Creep-ratchetting Elevated temperature Multiaxal stress Constitutive equation FEM SUS304 応力制御クリープラチェット Cr-Mo鋼実験構成式

项目摘要

Creep-ratchetting behavior at elevated tempareture on two types of heat resisting steels: 2 1/4Cr-1Mo steel at 600゜c and SUS304 stainless steel at 650゜c, has been experimentally examined in multiaxial stress state. In the mechanical retchetting tests under combined steady axial stress and cyclic shear straining, remarkable axial strain accumulation is found on both steels. The axial strain accumulation becomes larger with decreasing cyclic shear strain rate. In the creep test along circular stress path on 2 1/4Cr-1Mo steel, larger creep strain is observed than in uniaxial static creep tests. in the stress-controlled creep-ratchetting tests on SUS304, both in uniaxial and multiaxial stress states, the behavior is strongly affected by the stress ratio.To evalate the accuracy of the existing inelastic constitutive equations, the numerical simulations to the above-mentioned creep-ratchetting tests have been coducted by the equations. The superposition model and two of the unified models: the Chaboche model and the Miller model, were used for the simulation. The unified model gives better results for some of the tests, e. g., the creep along circular stress path, since they account the cree-plasticity interaction. However, the determination of material constants in the unified models are more difficult than that in the superposition model. All of these models can hardly express accurately the creep-ratchetting behavior guantitatively, and the further improvement is required.Creep-ratechetting behavior at room temperature has also been investigated on SUS304 and a carbon steel both in uniaxial and multiaxial stress state. The phenomenological constitutive models for the creep-ratchetting have been presented.The FEM program has been developed based on the unified constitutive equation presented by Chaboche. The program was checked through the numerical tests of s uniaxial tension and a tension of notched plate. The adaptive time-step has been discussed.

在多轴应力状态下，对两种耐热钢：2 1/4Cr-1Mo 钢在 600°c 和 SUS304 不锈钢在 650°c 的高温下的蠕变棘轮行为进行了实验研究。在稳定轴向应力和循环剪切应变组合下的机械回缩试验中，两种钢都发现了显着的轴向应变积累。随着循环剪切应变率的降低，轴向应变累积变得更大。在2 1/4Cr-1Mo钢的环形应力路径蠕变试验中，观察到比单轴静态蠕变试验更大的蠕变应变。在SUS304材料的应力控制蠕变棘轮试验中，无论是单轴还是多轴应力状态，其行为都受到应力比的强烈影响。为了评价现有非弹性本构方程的准确性，利用该方程对上述蠕变棘轮试验进行了数值模拟。使用叠加模型和两个统一模型：Chaboche 模型和 Miller 模型进行模拟。统一模型为某些测试提供了更好的结果，例如。例如，沿着圆形应力路径的蠕变，因为它们考虑了蠕变-塑性相互作用。然而，统一模型中材料常数的确定比叠加模型中的困难更大。所有这些模型都很难准确地定量地表达蠕变棘轮行为，需要进一步改进。还研究了SUS304和碳钢在单轴和多轴应力状态下的室温蠕变棘轮行为。提出了蠕变棘轮现象的唯象本构模型。有限元程序是根据Chaboche提出的统一本构方程开发的。通过单轴拉力和缺口板拉力的数值试验对程序进行了检验。已经讨论了自适应时间步长。