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Material high-temperature creep life-span accelerated test method

A technology of high temperature creep and creep rate, applied in the field of accelerated creep life test based on short-term stress relaxation, high temperature creep life accelerated test of materials, can solve the problem of difficult to obtain strain rate results, scientific and feasibility Problems such as questioning and extrapolation of creep data are far-fetched to achieve the effects of stepless expansion, reduction of high-temperature tests, and high conversion accuracy and reliability

Inactive Publication Date: 2008-11-19
EAST CHINA UNIV OF SCI & TECH
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Problems solved by technology

These methods inevitably lead to large errors, mainly because the relaxation stress-strain rate relationship is strongly dependent on the initial stress, and it is difficult to obtain stable strain rate results if the relaxation test time is too short, especially if the stress relaxation test is less than 24 hours On the other hand, the plastic deformation caused by the excessively increased relaxation initial strain to achieve acceleration becomes the main controlling factor, the extrapolated creep data obtained from this is very far-fetched and arbitrary, and the conversion accuracy is inevitably low, which is scientific and feasible. questioned

Method used

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  • Material high-temperature creep life-span accelerated test method
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  • Material high-temperature creep life-span accelerated test method

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Embodiment 1

[0055] Example 1 , High temperature creep life accelerated test

[0056] 1.1. Short-term stress relaxation test

[0057]The test is a uniaxial tensile stress relaxation test at 600°C. The test piece is a forged bar with a standard structure and size of 100mm in length and 10mm in diameter. The test time is set according to the design terminal stress of 160MPa and is determined naturally after the test. The test parameters are shown in Table 1 below.

[0058] Table 1. Stress relaxation test parameters of Cr10NiMoW2VNbN alloy

[0059] Initial stress MPa

300

325

350

375

400

450

Test time h

27

45

71

106

152

211

[0060] Obtain the time-stress curve according to the result of table 1, the result is as follows figure 1 shown.

[0061] 1.2. Construction of relaxation rate-stress curve

[0062] right figure 1 Numerically differentiating the relaxation curve shown, we get figure...

Embodiment 2

[0079] Example 2 , Creep test verification

[0080] In order to verify the reliability of the above method, the actual creep data and the conversion results of the short-term relaxation test were plotted together in the Figure 4 , for a comparison. Creep test data are taken from literature Yao H T, Shen S F, Xuan F Z, et al. Experimental Investigations on Mechanical Properties of a High Cr Ferritic Steel for USC Steam turbineRotor[A], Challenges of Power Engineering and Environment[C].Proceedings of the international conference on power engineering 2007. October 23-27, 2007, Hangzhou China, p: 1066-1070.

[0081] From Figure 4 It can be seen that the conversion results are in good agreement with the actual creep data; in addition, the converted material constant K=6.34×10 -33 , n=11.238 and the corresponding material constant 6.67×10 obtained according to the creep test data -33 , 11.18 are very close, so the accelerated creep test method is reliable and can be used fo...

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Abstract

The invention relates to a high temperature creep life accelerated test method of a material, which comprises: a plurality of groups of short time stress relaxation tests of the material at the same temperature, acquiring a relaxation rate-stress curve based on the numerical differentiation principle, forming a relaxation creep rate-stress curve by utilizing a relaxation equation, calculating creep data to build a creep curve, and building a steady state creep rate curve and a Norton creep equation. The method starts from the physical relation between relaxation and creep, covers rather broad properties of creep strain rate by utilizing the short time relaxation process, and educes broader creep data than that educed from general creep tests by above ten times, thereby effectively reducing the amount of high temperature creep tests and time of tests and providing basic data for development of new material and engineering application.

Description

technical field [0001] The invention belongs to the technical field of material testing, and in particular relates to a high-temperature creep life accelerated test method for materials, in particular to a creep life accelerated test technology based on short-term stress relaxation. Background technique [0002] The traditional high-temperature creep life test needs to last for a long time, and the obtained life data can only be extrapolated by 3 times. On the one hand, it limits the popularization and application of new materials (a long-term basic experiment is required to provide basic data for life design), on the other hand, a long-term high-temperature test wastes a lot of manpower and material resources. It is contrary to the important national policy of reducing consumption. [0003] At present, there are two methods of relaxation-creep transition for high-temperature material properties, one is a pure drawing method, and the other is a method combining calculation ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
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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