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Simple method for measuring fatigue crack propagation threshold value of metal material

A fatigue crack growth and metal material technology, which is applied in the field of measuring the fatigue crack growth threshold of metal materials, and can solve the problems of the fatigue crack growth threshold difference and so on.

Inactive Publication Date: 2013-12-18
INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] But since ΔK th There is no unified regulation on the measurement method, which leads to differences in the fatigue crack growth threshold measured by different methods even for materials in the same state.

Method used

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  • Simple method for measuring fatigue crack propagation threshold value of metal material
  • Simple method for measuring fatigue crack propagation threshold value of metal material
  • Simple method for measuring fatigue crack propagation threshold value of metal material

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0083] The hot-rolled Ti-24Nb-4Zr-8Sn alloy is processed into a standard three-point bending sample with a size of 47.25mm×11.25mm×5.50mm, and then the Ti-24Nb-4Zr-8Sn sample is used on a pre-grinding machine with 150# , 400#, 800#, 1200#, 2000# SiC sandpaper for grinding step by step. Rinse with absolute ethanol and water, dry it and put it in the sample box for later use.

[0084] In this example, the Ti-24Nb-4Zr-8Sn alloy is referred to Chinese patent application number: 200410092858.1, a superelastic low modulus titanium alloy and its preparation and processing method.

[0085] The process of the simple method for measuring the fatigue crack growth threshold of metal materials is as follows:

[0086] In this example, measure the fatigue crack growth threshold value ΔK of Ti-24Nb-4Zr-8Sn alloy at room temperature and atmospheric environment, stress ratio R=0.3 th , the sample to be tested is the above-mentioned standard three-point bending sample, the test instrument is a...

Embodiment 2

[0112] The difference from Example 1 is:

[0113] Process the 7075 aluminum alloy with a diameter of 15mm into a standard three-point bending sample with a size of 47.25mm×11.25mm×5.50mm, and then use 150#, 400#, 800#, 1200# , 2000# SiC sandpaper is polished step by step. Rinse with absolute ethanol and water, dry it and put it in the sample box for later use.

[0114] The process of the simple method for measuring the fatigue crack growth threshold of metal materials is as follows:

[0115] In this example, measure the fatigue crack growth threshold ΔK of 7075 aluminum alloy at room temperature and atmospheric environment, the stress ratio R=0.1, and the test frequency is 10HZ th , the sample to be tested is the above-mentioned standard three-point bending sample, and the test instrument is an Instron8872 fatigue testing machine.

[0116] ΔK 1 with ΔK t Selection and related experimental data preparation:

[0117] 7075 aluminum alloy σ obtained by experiment 0.2 =490MP...

Embodiment 3

[0136] The difference from Example 1 is:

[0137] The A533 steel of 60mm×20mm×10mm is processed into a standard three-point bending sample with a size of 47.25mm×11.25mm×5.50mm, and then the sample is used on the pre-grinding machine with 150#, 400#, 800#, 1200#, The 2000# SiC sandpaper is polished step by step. Rinse with absolute ethanol and water, dry it and put it in the sample box for later use.

[0138] The process of the simple method for measuring the fatigue crack growth threshold of metal materials is as follows:

[0139] In this example, the fatigue crack growth threshold ΔK of A533 steel is measured at room temperature and atmospheric environment, the stress ratio R=0.1, and the test frequency is 10HZ th , the sample to be tested is the above-mentioned standard three-point bending sample, and the test instrument is an Instron8872 fatigue testing machine.

[0140] ΔK 1 with ΔK t Selection and related experimental data preparation:

[0141] A533 steel σ obtaine...

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Abstract

The invention relates to the technical field of fatigue crack propagation, in particular to a simple method for measuring fatigue crack propagation threshold value of a metal material. The simple method comprises the steps of estimating the initial stress intensity factor range delta K1 and the fatigue crack propagation threshold value delta Kth by referring to related documents or experimental data firstly; selecting whether to use a single-stage experiment or a multi-stage experiment according to the suggestion of the invention; substituting the delta K1 into the formula provided by the invention and calculating the c value and the delta a value; finally calculating the fatigue crack propagation threshold value delta Kt according to the experimental data. The method is suitable for the metal material, and the measured fatigue crack propagation threshold value is in accordance with the national standard GB / T 6398-2000; furthermore, the measurement method disclosed by the invention is simple and easy to use, and can quickly obtain the fatigue crack propagation threshold value of the metal material.

Description

technical field [0001] The invention relates to the technical field of fatigue crack growth, in particular to a simple method for measuring the fatigue crack growth threshold of metal materials. Background technique [0002] Over the past few decades, damage tolerant design has been introduced to characterize the fatigue behavior of materials. Fatigue crack growth curves were used for fatigue performance design. Especially for porous and inclusion materials, the crack growth stage accounts for a large part of the fatigue life, and the crack growth is very important at this time. And the fatigue crack growth threshold ΔK th As an important performance index of materials, it has very important practical significance. [0003] Fatigue crack growth threshold ΔK th It refers to the range of stress intensity factor at the crack tip corresponding to when the fatigue crack growth rate is close to zero or the crack stops growing in the drop force (K) test. Usually, the fatigue cr...

Claims

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Application Information

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IPC IPC(8): G01N3/00
Inventor 张强李述军王皓亮侯文韬郝玉琳杨锐
Owner INST OF METAL RESEARCH - CHINESE ACAD OF SCI
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