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Method for converting creep data into material high-temperature stress relaxation data

A technology of stress relaxation and material constants, which is applied in special data processing applications, analytical materials, electrical digital data processing, etc., can solve the problems of low accuracy of results, unsatisfactory data accuracy, restrictions on promotion and application, etc.

Inactive Publication Date: 2010-01-13
EAST CHINA UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

There are many deficiencies in these methods, which limit the promotion and application of this technical method. The main manifestations are: the existing methods use time as the independent variable, and the scientific method should be a time-strain function with strain as the independent variable; data processing ignores The influence of the third stage of creep is eliminated, resulting in the accuracy of the converted data cannot meet the requirements; the initial strain rate of the time unit is used in the creep-relaxation data conversion process, and the change of the strain rate in the time unit is ignored, resulting in nonlinear parameters Fitting and the results are not accurate

Method used

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  • Method for converting creep data into material high-temperature stress relaxation data
  • Method for converting creep data into material high-temperature stress relaxation data
  • Method for converting creep data into material high-temperature stress relaxation data

Examples

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Embodiment 1

[0056] Example 1 , conversion calculation

[0057] The domestic 1Cr10NiMoW2VNbN alloy is used for steam turbine rotors, blades and bolts below 600 °C. The following materials will be used as an example for further details. It should be understood that the following examples are for the purpose of illustration only, and are not intended to limit the scope of the present invention.

[0058] 1. Obtain creep data

[0059] see figure 1 As shown, the creep test is a unidirectional creep tensile test at 600°C, and the creep stresses are 360, 315, 300, 285, 270 MPa. The test data are taken from relevant literature (Yao H T, Shen S F, Xuan F Z, et al .Experimental Investigations on Mechanical Properties of a High Cr Ferritic Steel for USCSteam turbine Rotor[A],Challenges of Power Engineering and Environment[C].Proceedings of the international conference on power engineering 2007.October 23-27,2007,HangzhouChina,p 1066-1070).

[0060] 2. Parameter fitting

[0061] Using a combina...

Embodiment 2

[0084] Example 2 , experimental verification

[0085] In order to verify the conversion results, stress relaxation tests at three initial stress levels of 350MPa, 300MPa, and 266MPa at 600°C were carried out. The conversion results and experimental results based on the K-R equation conversion model are plotted in image 3 , the conversion results based on the O-H equation conversion model and the experimental results are plotted in Figure 4 middle. In order to compare the present invention with other methods, the above three initial stress conversion calculations have been carried out by other methods, and the conversion results and experimental results are drawn in figure 1 middle.

[0086] Depend on figure 1 , 3 , 4 result calculations can get, two kinds of average rate model conversion result error rates of the present invention are respectively 4.1% and 4.5%, all very low, far lower than 37% and 26% of K-R and O-H conversion model; From image 3 with Figure 4 It ...

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Abstract

The invention relates to a method for converting creep data into material high-temperature stress relaxation data, which comprises the following steps: a method and a step for acquiring the material creep property data of a high-temperature component material at certain temperature and performing normalization processing on the material creep property data, a method for dividing the process of relaxation, and a process of creep-relaxation conversion. The method comprehensively considers the influences at different creep stages, improves the precision of data conversion from creep to relaxation, can acquire the relaxation property data satisfying the design requirements on engineering structures, and can be expected to replace relaxation tests having high requirements on experimental installations.

Description

technical field [0001] The invention belongs to the technical field of material testing and engineering structure design, and in particular relates to a method for converting high-temperature creep test data of materials into high-temperature stress relaxation data. Background technique [0002] High-temperature and high-pressure components in petrochemical, electric power and other fields are increasingly threatened by failure mechanisms such as creep and relaxation, which need to be fully considered and predicted in design and maintenance. From a mechanistic point of view, creep represents the process of irreversible deformation increasing with time under the condition of constant stress, while stress relaxation reflects the phenomenon that the stress in the component decreases with time under the condition of constant total strain. In essence, both mechanisms reflect the process of stress (or strain) changing with time, and there must be some correspondence or correlation...

Claims

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Application Information

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IPC IPC(8): G01N33/00G01N3/00G06F19/00
Inventor 轩福贞郭进全王正东涂善东
Owner EAST CHINA UNIV OF SCI & TECH
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