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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.

对两种耐热钢：2 1/4Cr-1Mo钢(600゜c)和SUS304不锈钢(650゜c)在多轴应力状态下的高温蠕变棘轮行为进行了实验研究。在稳态轴向应力和循环剪切应变联合作用下的力学回弹试验中，两种钢都有显著的轴向应变积累。循环剪切应变率越小，轴向应变累积越大。在2 1/4Cr-1Mo钢环向应力路径蠕变试验中，观察到的蠕变应变大于单轴静态蠕变试验。在SUS304的应力控制蠕变-棘轮试验中，无论是在单轴还是在多轴应力状态下，蠕变-棘轮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，用该方程对上述蠕变-棘轮试验进行了数值模拟。模拟采用了叠加模型和两个统一的模型：Chaboche模型和Miller模型。由于统一模型考虑了裂纹-塑性相互作用，所以对某些试验，如沿圆形应力路径的蠕变，给出了较好的结果。然而，在统一模型中确定材料常数比在叠加模型中要困难得多。这些模型都不能准确地定量描述蠕变棘轮行为，需要进一步改进。本文还研究了SUS304和碳钢在单轴和多轴应力状态下的室温蠕变行为。建立了蠕变棘轮的唯象本构模型，并基于Chaboche提出的统一本构方程编制了有限元程序。通过S单轴拉伸和缺口板拉伸的数值试验对程序进行了校核。对自适应时间步长进行了讨论。