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A Method of Calculating Fracture Toughness Using 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: 2019-11-08
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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  • A Method of Calculating Fracture Toughness Using Indentation Method

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[0061] The present invention is specifically described below in conjunction with accompanying drawing:

[0062] Such as Figure 1-2 Shown, a kind of indentation method calculates fracture toughness method, it is characterized in that: comprise the steps:

[0063] 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;

[0064] The indentation test 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.

[0065] 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 performed...

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Abstract

A method for calculating fracture toughness using an indentation method, belonging to the technical field of fracture toughness testing, and comprising the following steps: (1) obtaining the relationship between depth and load in material indentation and unloading phases; (2) obtaining plastic residual depth and contact depth state parameters according to a load displacement curve during material unloading; (3) using finite element software to predict that a material includes, under the action of an indenter, a radial displacement correction coefficient and a Berkovich indenter non-axisymmetric correction factor; (4) performing a uniaxial tensile test of a material, acquiring an elastic modulus of the material, and obtaining a critical porosity of the material by means of a GTN theory in combination with the finite element software; and (5) associating indentation work with fracture energy, and causing same to be in equivalence with strain energy density, so as to obtain a fracture toughness equation characterized by the critical plastic residual depth. The fracture toughness testing method can quickly acquire the elastic modulus and fracture toughness value of a material at low loss by means of a small-range indentation test 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...

Claims

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Application Information

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Patent Type & Authority Patents(China)
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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