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Cyclic Constitutive Relation and Estimation of Biaxial Low Cycle Fatigue Life at Elevated Temperature

高温下双轴低周疲劳寿命的循环本构关系及估算

基本信息

批准号：
60460084
负责人：
OHNAMI Masateru
金额：
$ 4.16万
依托单位：
Ritsumeikan University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1985
资助国家：
日本
起止时间：
1985 至 1986
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-60460084/
关键词：
High Temperature Low Cycle Fatigue Biaxial Stress Constitutive Relation Dislocation X-ray Diffraction 非比例負荷

项目摘要

Cyclic biaxial constitute relation was determined for an austenitic stainless steel SUS 304 and 1Cr-1Mo-1/4V aged and non-aged steels in the three test methods under combined push-pull and reversed torsion load at 823 K. The three test methods were the companion method, incremental/decremental method (I/D method) and step-up method. For 1Cr-1Mo-1/4V steel only the companion test was carried out. Proportional and non-proportional tests were carried out for SUS 304 steel in the I/D method. The major conclusions obtained are as follows.1. The biaxial cyclic constitutive relation in the three test methods is well correlated by the Mises equivalent stress and stress except 1Cr-1Mo-1/jV aged steel. The scatter of the data in the companion test is comparatively large. 2. The cyclic constitutive relation in the companion test differs from that in the I/D test. The cyclic hardening exponent in the companion test is larger than that in the I/D test.3. Larger cyclic stress amplitude is observed in the non-proportional test in comparison with the proportional test. The cause of the increase in the stress amplitude due to the non-proportional loading is discussed by TEM observations and X-ray diffraction. A simple equation to estimate the stress amplitude in the non-proportinal test is proposed. The estimated results based on the equation agree well with the experimental results.4. FEM analysis is made for plate notched specimens using the cyclic constitutive relations obtained in the companion and the I/D tests in order to know how the difference in the constitutive relation affects the low cycle fatigue design life. The calculated results using both the constitutive relations do not differ each other, so that the difference in the constitutive relation due to the test method does not have an large effect on the design fatigue life.

在823 K温度下，测定了奥氏体不锈钢SUS 304和1Cr-1 Mo-1/4V时效钢及未时效钢在3种试验方法下的推拉-扭转复合载荷下的循环双轴本构关系。三种测试方法分别为伴随法、递增/递减法（I/D法）和递增法。对1Cr-1 Mo-1/4V钢只进行了伴随试验。采用I/D法对SUS 304钢进行了比例和非比例试验。主要结论如下：1.除1Cr-1 Mo-1/jV时效钢外，三种试验方法的双轴循环本构关系均与Mises等效应力和应力有较好的相关性。伴随试验数据的离散性较大。2.伴随试验中的循环本构关系不同于I/D试验中的循环本构关系。伴随试验的循环硬化指数大于I/D试验的循环硬化指数.与比例试验相比，非比例试验的循环应力幅更大。通过透射电镜观察和X射线衍射分析，讨论了非比例加载引起应力幅增大的原因。本文提出了一个简单的非比例试验应力幅估算公式。基于该方程的估算结果与实验结果吻合较好.为了了解本构关系的差异对低周疲劳设计寿命的影响，利用同伴试验和I/D试验得到的循环本构关系对平板缺口试件进行了有限元分析。使用这两种本构关系的计算结果彼此没有差异，因此，由于试验方法导致的本构关系的差异对设计疲劳寿命没有很大影响。