Method for evaluating tearing toughness of ductile metal materials

Abstract

The invention relates to the field of mechanical property evaluation and characterization of materials, and in particular relates to a method for evaluating the tearing toughness of ductile metal materials. The method is characterized in that through carrying out a tearing test on ductile metal materials by using three-leg trouser-shaped samples, a characteristic that applied loadings in the process of tearing are unchanged is obtained, thereby providing a powerful test basis for the proposition of a tearing toughness concept, thereby obtaining a defined tearing toughness which is shown in a formula as follows: Gamma = FS / 2 t, and used for evaluating the toughness or crack propagation resistance of ductile materials. The tearing test method and the tearing toughness concept provide an effective thought for knowing an inversion relation between the strength and plasticity (toughness) of a material, therefore, a new reference criterion is provided for selecting materials (the strength and plasticity are fitted better) for actual engineering. As for ductile sheet metals, a crack propagation process and a fracture process can be described more accurately by using the tearing toughness, which has a vital significance to the evaluation and characterization of engineering applications and mechanical properties of materials.

Description

technical field

[0001] The invention relates to the field of evaluation and characterization of mechanical properties of materials, and specifically relates to a method for evaluating the tear toughness of ductile metal materials. The tear toughness is defined by using the three-legged trousers tearing method to characterize the resistance of the material to crack propagation resistance. Background technique

[0002] The mechanical properties of ductile metal materials are mostly measured by unidirectional loading tensile tests. However, the material has high strength and is accompanied by a lack of plasticity. This inverted relationship between strength and plasticity has caused huge problems in engineering material selection. How to better achieve strong and tough cooperation has become the key to the problem, which puts forward more comprehensive requirements for the evaluation of the mechanical properties of materials. On the other hand, fracture toughness (K IC ) to ch...

Examples

Embodiment 1

[0040] Material preparation: Cut the 3mm thick cold-rolled 20 steel plate into thin slices of 40mm×20mm×0.5mm along the rolling direction, cut two parallel notches in the length direction of the thin slices, the widths of the notches are 8mm and 12mm respectively, and the lengths of the notches are respectively 20mm( Figure 1-2 ); Cut the 3mm thick cold-rolled 20 steel plate along the rolling direction into a tensile test piece whose gauge length is 16mm×3mm×3mm.

[0041] Heat treatment: Some samples are quenched at 920°C, then tempered at 200°C, 400°C, 600°C, and 700°C for 2 hours, and the samples are polished and polished;

[0042] Performance Testing:

[0043] The tensile samples after heat treatment at different temperatures were subjected to tensile tests, and the test results were as follows: Figure 5 shown.

[0044] The prepared tear sample (notch width 8mm) is clamped to the testing machine, and the tear test is carried out to obtain the applied load-displacement ...

Embodiment 2

[0056] Material preparation: Cut a 0.5mm thick cold-rolled aluminum sheet into 40mm×20mm slices along the rolling direction, and cut two parallel notches (that is, three-leg trousers-shaped tear samples) in the length direction of the slices. The widths of the notches are respectively 8mm, 10mm, 12mm, the gap length is 20mm ( Figure 1-2 ), grinding the tear sample and performing mechanical polishing;

[0057] The prepared tear sample (notch width 8mm) was clamped to the testing machine, and the tear test was carried out to obtain the applied load-displacement curve during the tearing process. According to the obtained load-displacement curve, using the definition of tear toughness γ=F S / 2t to calculate the tear toughness of the material.

[0058] In this embodiment, the specific calculation process of tear toughness γ is as follows:

[0059] Intercept the part of the tear load-displacement curve where the load is stable, and use formula (2) in the calculation process of t...

Embodiment 3

[0061] Material preparation: Cut the 0.5mm thick cold-rolled copper sheet into 40mm×20mm slices along the rolling direction, cut two parallel notches in the length direction of the slices, the width of the notch is 8mm, 10mm, 12mm, and the length of the notch is 20mm ( Figure 1-2 ), grinding the tear sample and performing mechanical polishing;

[0062] The prepared tear sample is clamped to the testing machine, and the tear test is carried out to obtain the applied load-displacement curve during the tearing process. According to the obtained load-displacement curve, using the definition of tear toughness γ=F S / 2t to calculate the tear toughness of the material.

[0063] In this embodiment, the calculation process of the tear toughness γ with a notch width of 8 mm is as follows:

[0064] Intercept the part of the tear load-displacement curve where the load is stable, and use the formula (2) in the calculation of the tear toughness to obtain the tear toughness of the 0.5mm ...

technical field

[0001] The invention relates to the field of evaluation and characterization of mechanical properties of materials, and specifically relates to a method for evaluating the tear toughness of ductile metal materials. The tear toughness is defined by using the three-legged trousers tearing method to characterize the resistance of the material to crack propagation resistance. Background technique

[0002] The mechanical properties of ductile metal materials are mostly measured by unidirectional loading tensile tests. However, the material has high strength and is accompanied by a lack of plasticity. This inverted relationship between strength and plasticity has caused huge problems in engineering material selection. How to better achieve strong and tough cooperation has become the key to the problem, which puts forward more comprehensive requirements for the evaluation of the mechanical properties of materials. On the other hand, fracture toughness (K IC ) to ch...

Examples

Embodiment 1

[0040] Material preparation: Cut the 3mm thick cold-rolled 20 steel plate into thin slices of 40mm×20mm×0.5mm along the rolling direction, cut two parallel notches in the length direction of the thin slices, the widths of the notches are 8mm and 12mm respectively, and the lengths of the notches are respectively 20mm( Figure 1-2 ); Cut the 3mm thick cold-rolled 20 steel plate along the rolling direction into a tensile test piece whose gauge length is 16mm×3mm×3mm.

[0041] Heat treatment: Some samples are quenched at 920°C, then tempered at 200°C, 400°C, 600°C, and 700°C for 2 hours, and the samples are polished and polished;

[0042] Performance Testing:

[0043] The tensile samples after heat treatment at different temperatures were subjected to tensile tests, and the test results were as follows: Figure 5 shown.

[0044] The prepared tear sample (notch width 8mm) is clamped to the testing machine, and the tear test is carried out to obtain the applied load-displacement ...

Embodiment 2

[0056] Material preparation: Cut a 0.5mm thick cold-rolled aluminum sheet into 40mm×20mm slices along the rolling direction, and cut two parallel notches (that is, three-leg trousers-shaped tear samples) in the length direction of the slices. The widths of the notches are respectively 8mm, 10mm, 12mm, the gap length is 20mm ( Figure 1-2 ), grinding the tear sample and performing mechanical polishing;

[0057] The prepared tear sample (notch width 8mm) was clamped to the testing machine, and the tear test was carried out to obtain the applied load-displacement curve during the tearing process. According to the obtained load-displacement curve, using the definition of tear toughness γ=F S / 2t to calculate the tear toughness of the material.

[0058] In this embodiment, the specific calculation process of tear toughness γ is as follows:

[0059] Intercept the part of the tear load-displacement curve where the load is stable, and use formula (2) in the calculation process of t...

Embodiment 3

[0061] Material preparation: Cut the 0.5mm thick cold-rolled copper sheet into 40mm×20mm slices along the rolling direction, cut two parallel notches in the length direction of the slices, the width of the notch is 8mm, 10mm, 12mm, and the length of the notch is 20mm ( Figure 1-2 ), grinding the tear sample and performing mechanical polishing;

[0062] The prepared tear sample is clamped to the testing machine, and the tear test is carried out to obtain the applied load-displacement curve during the tearing process. According to the obtained load-displacement curve, using the definition of tear toughness γ=F S / 2t to calculate the tear toughness of the material.

[0063] In this embodiment, the calculation process of the tear toughness γ with a notch width of 8 mm is as follows:

[0064] Intercept the part of the tear load-displacement curve where the load is stable, and use the formula (2) in the calculation of the tear toughness to obtain the tear toughness of the 0.5mm ...

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