Prediction method for residual stress and damage caused by stress relaxation of high-temperature material
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A technique of stress relaxation and residual stress, used in analyzing materials, measuring devices, instruments, etc.
Inactive Publication Date: 2014-07-23
ANYANG INST OF TECH
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[0004] The purpose of the present invention is to overcome the existing problems and defects in the existing conversion prediction technology, introduce the principle of continuous damage into stress relaxation,
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Embodiment 1
[0054] Domestic 1Crl0NiMoW2VNbN steel, used for 600. Below C, steam turbine rotors, blades and bolts, take this material as an example for further explanation. It should be understood that the following examples are only for illustrative purposes, and not for limiting the scope of the present invention.
[0055] 1. Get creep data
[0056] The creep test is a unidirectional creep tensile test at 600℃, the creep stress is 315, 300, 285, 270 MPa, the test data is as attached figure 1 Shown.
[0057] 2. Parameter fitting
[0058] The test data is combined with multi-level linear and nonlinear regression to obtain the material constants. 600. The material elastic modulus E under C is 1.68×10 5 MPa, J-H creep model material constants K, A, n, m, p, q are: 6.7×10 -33 , 1.28×10 -24 , 11.19, 11.12, 8.1l, 6.83, O-H creep model material constants G, B, d, β, δ, φ, In order: 3.6×10 -17 , 4.14×10 -11 , 5.157, 10.02, -0.60, 3.29, 4.75.
[0059] 3. Establish the concrete expression of the stress...
Embodiment 2
[0073] In order to verify the conversion results, stress relaxation tests with three initial stress levels of 350, 300, and 266 MPa at 600°C were carried out; the conversion results of the present invention and the experimental results are shown in the attached file. figure 2 , 3 To compare. Attached figure 2 , 3 It can be seen that the conversion result of the stress relaxation continuous damage model based on the JH creep damage model of the present invention is slightly higher than the experimental results, while the conversion result of the stress relaxation continuous damage model based on the OH creep model is in good agreement with the experimental results. This may be related to the latter (the former does not) characterize the first stage of creep corresponding to stress relaxation, so the latter is recommended. In addition, the long-term conversion results of the three initial stress levels of the two relaxation damage models are basically gathered into a curve, whic...
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Abstract
The invention discloses a prediction method for residual stress and damage caused by stress relaxation of a high-temperature material. The predication method mainly comprises the following steps: based on two creep deformation damage models and a stress relaxation strain model, establishing a corresponding stress relaxation continuous damage model; acquiring the material creep deformation performance data of a high-temperature component material at a temperature; based on the creep deformation performance data, fitting out corresponding material constants corresponding to the two creep deformation damage models; and by employing a data analysis technology and through program calculation, solving the stress relaxation continuous damage model, and finally converting the creep deformation data into stress relaxation data, so as to obtain a stress relaxation curve and a stress relaxation damage cure, and further to predict the residual stress and the damage degree caused by the stress relaxation of the high-temperature material. According to the method, the precise association of obtaining the relaxation behavior from the creep deformation data is established, and the complete prediction method for residual stress and damage caused by stress relaxation of the high-temperature is established, and a new approach is provided for stress relaxation strength design and management maintenance of high-temperature components.
Description
Technical field [0001] The invention belongs to the technical field of material testing and engineering structure strength design, and specifically relates to a method for converting high-temperature creep test data of materials into high-temperature stress relaxation data, especially the high-temperature stress relaxation residual stress and damage based on the principle of continuous damage method of prediction. Background technique [0002] High-temperature fasteners are characterized by performance degradation (damage) during service. When the damage accumulates to a certain extent, it will cause the joint system to leak or even break and other serious catastrophic accidents. In order to evaluate and predict the relaxation performance of high-temperature bolts, a common practice is to perform a long-term stress relaxation test, which leads to a large consumption of energy, manpower, and materials. Creep is an important part of the design of high-temperature components. Relax...
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