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On the Applicability of the Schwalbe's Model to the Fracture Toughness Calculation in 7075 Aluminum Alloys

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Advanced Performance Materials

Abstract

Four 7075-T651 aluminum alloys have been tested in tension in order to assess the applicability of the Schwalbe's model to the fracture toughness calculation. Standard K IC tests were performed on compact tension samples at room temperature, and the results compared with those from the Schwalbe's model which takes into account several mechanical properties derived from a conventional tensile test applied on round unnotched tensile samples, and the average dimple size of the corresponding fracture surfaces. The values of K IC calculated through the Schwalbe's model, correlate qualitatively well with those from the standard technique.

Fracture toughness deterioration is accompanied by a loss of the true fracture strain, strain hardening capacity and average dimple size. On the other hand, the higher the Zn/Mg ratio, the volume fraction of precipitates and the yield strength, the lower the fracture toughness. All these effects are originated in the presence of matrix precipitates. Therefore, the reduction in K IC can be explained in terms of the matrix response to the applied stress field as a function of the differences in volume fraction of the strengthening precipitates.

The round tension samples corresponding to the four materials, failed in a predominantly ductile transgranular fashion, which facilitates the application of the Schwalbe's model based in the characteristic dimples, developed in this mode of fracture, as a microstructural element size.

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  1. School of Metallurgical Engineering and Materials Science, Central University of Venezuela (UCV), Apartado 47514, Caracas, 1041-A, Venezuela

    O.A. Hilders & N.D. Peña

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  1. O.A. Hilders
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Hilders, O., Peña, N. On the Applicability of the Schwalbe's Model to the Fracture Toughness Calculation in 7075 Aluminum Alloys. Advanced Performance Materials 4, 49–61 (1997). https://doi.org/10.1023/A:1008620232065

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