Acceleration condition rationality evaluation method for material creep life test

A technology of creep life and evaluation method, which is applied in the direction of analyzing materials, using stable tension/pressure to test the strength of materials, measuring devices, etc., which can solve the lack of theoretical basis, the inability to meet the requirements of creep evaluation, and the test without temperature setting Issues such as the impact of the rationality of the scheme, to achieve the effect of flexible verification and meeting the evaluation requirements

Pending Publication Date: 2022-02-25
RES INST OF PHYSICAL & CHEM ENG OF NUCLEAR IND
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  • Application Information

AI Technical Summary

Problems solved by technology

Although the Creep Rupture Data Evaluation Method (CRDA) promulgated by the European Creep Collaboration Committee (ECCC) uses methods such as isotherm change, data fit, and deleted data re-evaluation to consider the extrapolation of the stress region, most of the evaluation indicators The determination is based on the experience of the test personnel and lacks a theoretical basis. At the same time, the influence of the temperature setting on the rationality of the test plan is not considered.
Excessively increasing the accelerated test conditions may lead to changes in the creep deformation and failure mechanism of the material, and the obtained extrapolation results cannot meet the creep evaluation requirements of structural materials under high confidence

Method used

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  • Acceleration condition rationality evaluation method for material creep life test
  • Acceleration condition rationality evaluation method for material creep life test
  • Acceleration condition rationality evaluation method for material creep life test

Examples

Experimental program
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Embodiment 1

[0042] An evaluation method for accelerated conditions of material creep life test, such as figure 1 shown, including the following steps:

[0043] Step 1: Carry out a creep experiment on the sample according to the standard method. After the experiment is completed, record the experimental conditions and steady-state creep rate of the sample. The experimental conditions include temperature conditions and stress conditions; the temperature conditions include at least three Different temperatures, the stress conditions in step 1 include at least four different stresses;

[0044] Step 2: Select the creep data under the same temperature conditions, divide the creep data subgroups according to the order of the experimental stress from small to large according to the set minimum stress levels, and gradually increase the number of experimental stresses in each creep data subgroup. Stress level, obtain a creep data set for stress evaluation at a predetermined temperature, substitute...

Embodiment 2

[0058] According to the method in Example 1, this example selects a 7-series high-strength aluminum alloy pre-forged billet (T6 state) as the research object, and the sampling direction of the creep sample is the inner radial direction of the billet (perpendicular to the forging direction of the pre-forged billet). The sample size refers to GB / T2039-1997 "Metal Tensile Creep and Durability Test Method". There are 3 experimental temperature levels (temperature conditions), 40°C, 60°C, and 80°C, and 6 experimental stress levels (stress conditions), 450MPa, 500MPa, 550MPa, 580MPa, 600MPa, and 620MPa.

[0059] Step 1. After the creep life acceleration test is completed, record the experimental conditions (temperature, stress) and steady-state creep rate of the sample. The data distribution is as follows: figure 2 As shown, under each temperature and stress condition, do three sets of parallel tests;

[0060] Step 2, set the minimum number of stress levels to 3, select the creep ...

Embodiment 3

[0069] According to the method of Example 1, this example selects 316H stainless steel plate as the research object, and the sampling direction of the creep sample is the in-plane rolling direction. The sample size refers to GB / T 2039-1997 "Metal Tensile Creep and Endurance Test Method". There are three experimental temperature levels (temperature conditions), namely 500°C, 550°C, and 600°C, and five experimental stress levels (stress conditions), which are 200MPa, 250MPa, 300MPa, 350MPa, and 400MPa.

[0070] Step 1. After the creep life acceleration test is completed, record the experimental conditions (temperature, stress) and steady-state creep rate of the sample. The data distribution is as follows: Figure 5 As shown, under each temperature and stress condition, do three sets of parallel tests;

[0071] Step 2, the minimum number of stress levels is set to 2, and the creep data under the temperature conditions of 500°C, 550°C, and 600°C are respectively selected, and the...

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Abstract

The invention discloses an acceleration condition rationality evaluation method for a material creep life test. The method comprises the following steps: recording experimental conditions and data of a sample, sampling and calculating creep activation volumes in different stress ranges at specified temperature and creep activation energy in different temperature ranges under specified stress conditions, summarizing the data, checking whether normal distribution is met or not, checking whether an outlier exists or not, and judging whether the experimental conditions are reasonable or not. Based on the method, the upper limit of the creep life test condition of the material can be accurately determined. In addition, according to the method, the consistency of the creep mechanism of the material under the accelerated experiment condition is evaluated from the perspective of the creep mechanism of the material. And meanwhile, the rationality of an acceleration test scheme can be more flexibly verified, and the evaluation requirements of materials under different design indexes are met.

Description

technical field [0001] The invention relates to the technical field of material accelerated life tests, in particular to a method for evaluating the rationality of accelerated conditions for material creep life tests. Background technique [0002] Accelerated life test usually means that on the basis of reasonable engineering and statistical assumptions, the statistical model related to the physical failure law is used to convert the reliability information obtained under the accelerated environment beyond the normal stress level, and the test piece is obtained at the rated stress. A test method for reproducible numerical estimation of reliability characteristics at different levels. In order to complete the creep life evaluation of the material in the shortest possible test time, the basic idea of ​​the accelerated creep life test is to use the creep behavior characteristics of the material under high temperature and high stress to extrapolate the creep performance under th...

Claims

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Application Information

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IPC IPC(8): G01N3/08G01N3/02
CPCG01N3/08G01N3/02G01N2203/0003G01N2203/0016G01N2203/0071Y02P90/30
Inventor 李昂张毅陈开媛吴福高蔚
Owner RES INST OF PHYSICAL & CHEM ENG OF NUCLEAR IND
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