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Method for calculating fracture toughness through indentation method

A technology of fracture toughness and indentation method, applied in the direction of applying stable tension/pressure to test material strength, test material hardness, etc., can solve problems such as unreasonable, large errors, and testing, and achieve the effect of low-loss acquisition

Active Publication Date: 2019-06-18
江苏嘉易安科技有限公司
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Problems solved by technology

When the continuous ball indentation test of IEF is used to test the fracture toughness, because of the geometric shape of the ball, it needs to be indented to a greater depth, and it cannot be tested on some gradient materials and bends; while the Berkovich indenter calculates the error of the reduced elastic modulus Larger, the existing indentation method is unreasonable, so it is urgent to improve

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  • Method for calculating fracture toughness through indentation method
  • Method for calculating fracture toughness through indentation method
  • Method for calculating fracture toughness through indentation method

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Embodiment Construction

[0060] The present invention is specifically described below in conjunction with accompanying drawing:

[0061] Such as Figure 1-2 Shown, a kind of indentation method calculates fracture toughness method, it is characterized in that: comprise the steps:

[0062] Step (1), based on the indentation experiment, at a constant rate, obtain the full load-displacement curve under the unloading condition of no less than 6 times;

[0063] The indentation experiment adopts the method of continuous loading and unloading of the constant Berkovich indenter. The indenter is loaded at least 6 times at a loading rate of 50mN / s, and unloaded after each loading to obtain the full load-displacement curve.

[0064] In step (2), a power function parameter fitting is performed on each unloading curve to obtain the state parameters of the plastic residual depth and contact depth, and the unloading stiffness at the unloading point of each curve is calculated, and then a straight line fitting is per...

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Abstract

The invention belongs to the technical field of fracture toughness test and provides a method for calculating fracture toughness through an indentation method. The method comprises the following steps: 1) obtaining relationship between depth and load during material pressing-in and unloading stages; 2) obtaining plastic residual depth and contact depth state parameters according to a load-displacement curve during material unloading; 3) predicting a radial displacement correction factor and a Berkovich pressing head non-axisymmetric correction factor of the material under the function of a pressing head by utilizing finite element software; 4) carrying out material uniaxial tension experiment to obtain material elasticity modulus, and obtaining critical hole rate of the material based on the GTN theory with the help of the finite element software; and 5) associating indentation work with fracture energy and carrying out equivalence with strain energy density to obtain a fracture toughness equation characterized by the critical plastic residual depth. The fracture toughness test method can quickly obtain the elastic modulus and the fracture toughness value of the material at low loss through a small-range indentation experiment of the material.

Description

technical field [0001] The invention relates to the technical field of fracture toughness testing, in particular to a method for calculating fracture toughness by using an indentation method. Background technique [0002] With the continuous development of aerospace engineering, reactor engineering, welding technology and petroleum engineering, the demand for testing the mechanical properties of metal materials is increasing. There are a large number of in-service equipment in thermal power, nuclear power, metallurgy, petrochemical and other industries. Traditional sampling tests can obtain more comprehensive performance parameters of in-service equipment materials, but sampling tests are generally destructive and are not suitable for in-service equipment. The indentation method does not require sampling, has non-destructive characteristics, and can accurately and reliably obtain the mechanical properties of in-service equipment materials. The volume of the indentation test...

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Application Information

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IPC IPC(8): G01N3/08G01N3/42
CPCG01N3/08G01N3/42
Inventor 张玉财陆敏捷蒋文春涂善东张显程
Owner 江苏嘉易安科技有限公司
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