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Application of cyclic hardening model based on weld dislocation entanglement in welded joint fatigue life prediction

A technology for fatigue life prediction and welded joints, which is applied in special data processing applications, instruments, geometric CAD, etc., can solve the problems of fatigue fracture in the center of the weld and the inability to explain the microscopic mechanism, etc., and achieve reliable results, convenient operation, and reasonable design Effect

Active Publication Date: 2021-08-10
SICHUAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003] In recent years, some cyclic hardening models have been established at home and abroad, but these cyclic hardening models are based on macroscopic mechanical parameters, which cannot explain the microscopic mechanism of fatigue failure. In the fatigue process, the morphology of dislocations determines its Important Mechanisms of Cyclic Plastic Deformation
Moreover, when the welded joints of steel work under fatigue failure conditions, fatigue fractures often occur at the center of the weld

Method used

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  • Application of cyclic hardening model based on weld dislocation entanglement in welded joint fatigue life prediction
  • Application of cyclic hardening model based on weld dislocation entanglement in welded joint fatigue life prediction
  • Application of cyclic hardening model based on weld dislocation entanglement in welded joint fatigue life prediction

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Experimental program
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Effect test

Embodiment 1

[0059]The new heat-resistant steel Sanicro 25 steel pipe is selected as the base material, and the Sanicro 25 steel pipe is butted by manual tungsten argon arc welding. A low cycle fatigue test with a total strain amplitude of 0.4% was performed on the welded joints at 700°C. For specific experimental procedures, please refer to the literature "Low cycle fatigue behavior and microstructure evolution of novel 9Cr–3W–3Co tempered martensitic steel at 650℃" (Jing H, Luo Z, Xu L, etal. Materials Science & Engineering A, 2018, 731.) record is carried out.

[0060] Then, according to the obtained experimental data, the plastic strain range Δε under different cycles N is obtained p value. Then use the above formula (14) to fit N and Δε p The value of , the fitting result is as follows figure 1 shown.

[0061] Therefore, formula (14) can be determined as:

[0062]

[0063] According to the experimental parameters, Δε t = 0.008 and E = 154.6 GPa. Put formula (S1), Δε t and ...

Embodiment 2

[0067] 316H austenitic stainless steel welded joints are selected as the verification object. For welded joints at 550°C and a strain rate of 1 x 10 -3 the s -1 Low cycle fatigue tests were performed with a total strain amplitude of 0.5%. For specific experimental procedures, refer to the literature "Low cyclefatigue behavior and microstructure evolution of a novel 9Cr–3W–3Co tempered martensitic steel at 650°C" (Jing H, Luo Z, Xu L, et al. Materials Science & Engineering A, 2018, 731.) Recording is carried out.

[0068] Then, according to the obtained experimental data, the plastic strain range Δε under different cycles N is obtained p value. Then use the above formula (14) to fit N and Δε p The value of , the fitting result is as follows image 3 shown.

[0069] Therefore, formula (14) can be determined as:

[0070]

[0071] According to the experimental parameters, Δε t = 0.01 and E = 163.33 GPa. The formula (S3), Δε t and E are brought into the above formula ...

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Abstract

The invention provides an application of a cyclic hardening model based on weld dislocation entanglement in welded joint fatigue life prediction, and the cyclic hardening model is shown in the figure. Based on weld dislocation entanglement, Meanwhile, the influence of flow stress caused by weld dislocation entanglement and back stress generated by the hindering effect of a weld grain boundary on dislocation on the cyclic yield strength is considered, a cyclic hardening model of a welded joint is established on the basis, and the model well explains the relationship among the maximum stress, the cycle index and the plastic strain. A microscopic mechanism during fatigue failure based on weld dislocation entanglement is explained, so that the cyclic deformation behavior of the welded joint can be evaluated more quickly and accurately, and a better theoretical basis is provided for prediction of the fatigue life of the welded joint.

Description

technical field [0001] The invention relates to the technical field of component fatigue life prediction, in particular to the application of a cyclic hardening model based on weld dislocation entanglement in the fatigue life prediction of welded joints. Background technique [0002] Fatigue failure widely exists in engineering components, so it is very necessary to effectively predict the fatigue life of components, and the weak link in engineering components (such as welded joints) is the most prone to fatigue failure. Therefore, in order to ensure the safe operation of engineering components, the cyclic plastic deformation mechanism of welded joints needs to be studied. The fatigue performance of welded joints depends on the chemical composition of the welding consumables and the welding process. In order to rationally design welding consumables, shorten the development time of welding consumables, and select the welding process correctly, the relationship between weld m...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F30/17G06F119/04G06F119/14
CPCG06F30/17G06F2119/04G06F2119/14Y02P90/30
Inventor 李海舟刘永杰王清远
Owner SICHUAN UNIV
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