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Application of cyclic hardening model based on weld dislocation winding precipitation phase in welded joint fatigue life prediction

A fatigue life prediction, welding joint technology, applied in special data processing applications, design optimization/simulation, instruments, etc., can solve the problems of fatigue fracture in the center of the weld, inability to explain the microscopic mechanism, etc., to achieve reliable results, convenient calculation, Well-designed effects

Active Publication Date: 2021-08-10
SICHUAN UNIV
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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, and for steels strengthened by precipitation phase, in the process of cyclic plastic deformation , the precipitated phase will precipitate and generate a large number of dislocations, so the interaction of dislocations and precipitated phases is the mechanism of cyclic plastic deformation of this steel
At the same time, when the welded joints of steel work under the condition of fatigue failure, fatigue fracture often occurs at the center of the weld

Method used

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

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Experimental program
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Effect test

Embodiment 1

[0045] The new heat-resistant steel Sanicro 25 steel pipe is selected as the base material. Butt joints of Sanicro 25 steel pipes are performed by manual argon tungsten arc welding. Low cycle fatigue tests with a total strain amplitude of 0.5% were 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.

[0046] 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 (5) to fit N and Δε p The value of , the fitting result is as follows figure 1 shown.

[0047] Therefore, formula (5) can be determined as:

[0048]

[0049] According to the experimental parameters, Δε t = 0.01 and E = 126.8 GPa. Put formula (S1),...

Embodiment 2

[0053] 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 document "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.) conduct.

[0054] 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 (5) to fit N and Δε p The value of , the fitting result is as follows image 3 shown.

[0055] Therefore, formula (5) can be determined as:

[0056]

[0057] 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 (4), the maximum stre...

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Abstract

The invention provides an application of a cyclic hardening model based on a weld dislocation winding precipitation phase in welded joint fatigue life prediction, and the cyclic hardening model is as follows: in the formula, the method takes the weld dislocation winding precipitation phase as a basis, and takes flow stress caused by a non-uniform dislocation structure of the weld dislocation winding precipitation phase into consideration at the same time; the influence of back stress caused by dislocation winding precipitation phases in a welding seam and back stress generated by the blocking effect of a welding seam grain boundary on dislocation on the cyclic yield strength is achieved, a cyclic hardening model of a welding joint is established on the basis, and the model well explains the relation among the maximum stress, the cycle index and the plastic strain; and a microscopic mechanism during fatigue failure based on a weld dislocation winding precipitation phase is explained, and the cyclic deformation behavior of the welded joint can be evaluated more quickly and accurately, so that 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 fatigue life prediction of components, in particular to the application of a cyclic hardening model based on weld dislocation winding precipitation phase in the prediction of fatigue life 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 relat...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F30/17G06F30/28G06F119/04G06F119/14
CPCG06F30/17G06F30/28G06F2119/04G06F2119/14Y02P90/30
Inventor 李海舟刘永杰王清远
Owner SICHUAN UNIV
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