Evaluation of fracture toughness and Charpy V-notch test correlations for selected Al alloys

Abstract

This research experimentally compared the correlations on the fracture toughness using Charpy V-notch tests. The fracture toughness tests are expensive, complex, and unreliable. Therefore, researchers developed correlations using Charpy V-notch tests to estimate fracture toughness, thereby structural integrity assessment. For the current work, nine different fracture toughness correlations were selected using the existing literature and most common Al alloys, including 2024-T4, 6061-T6, and 7075-T6, were chosen as testing materials.. Tensile tests were utilized to determine the deformation behavior of the tested alloys. Also, Charpy V-notch tests were carried out to obtain absorbed energy during the low impact conditions. Rupture strain, yield, and ultimate tensile strengths of the alloys were determined by tensile testing. Charpy V-notch test results revealed that the energy absorption ability of the 6061-T6 Al alloy is roughly two times higher than the 2024-T4 and roughly four times higher than the 7075-T6 Al alloy. The fracture toughness estimations resulted in a broad range of values in which the highest and lowest values were obtained when the equations of Li et al. and Roberts and Newton were employed, respectively. The experimentally obtained fracture toughness values attained from the literature were used to define the error of each correlation. The correlation developed by Lucan et al. yielded the lowest average error with an error percentage of 15.6%. Lastly, the ductile fracture of the 6061-T6 Al alloy tensile test specimens executed at the quasi-static conditions was attributed to having a higher fracture toughness.

Keywords

• Fracture Toughness
• Charpy V-notch test
• Deformation Behavior
• 2024-T4 Al Alloy
• 6061-T6 Al Alloy
• 7075-T6 Al alloy

References

1. [1] Smith, R.J., Horn, A.J., Sherry, A.H., (2018). Relating Charpy energy to fracture toughness in the lower transition region using a Weibull stress dependent energy scaling model. International Journal of Pressure Vessels and Piping. 166: 72–83. doi: 10.1016/j.ijpvp.2018.06.001.
2. [2] Anderson, T.L., (2005). Fracture Mechanics. Boca Raton: CRC Press Taylor & Francis Group.
3. [3] (2020). Standard Test Method for Linear-Elastic Plane-Strain Fracture Toughness of Metallic Materials. West Conshohocken, PA.
4. [4] Ritchie, R.O., Knott, J.F., Rice, J.R., (1973). On the relationship between critical tensile stress and fracture toughness in mild steel. Journal of the Mechanics and Physics of Solids. 21(6): 395–410. doi: 10.1016/0022-5096(73)90008-2.
5. [5] Rossoll, A., Berdin, C., Prioul, C., (2002). Determination of the fracture toughness of a low alloy steel by the instrumented charpy impact test. International Journal of Fracture. 115(3): 205–26. doi: 10.1023/A:1016323522441.
6. [6] Schindler, H.J., Morf, U., (1993). A closer look at estimation of fracture toughness from Charpy V-notch tests. International Journal of Pressure Vessels and Piping. 55(2): 203–12. doi: 10.1016/0308-0161(93)90028-R.
7. [7] A Salemi Golezani., (2013). The Effect of Microstructure on Estimation of the Fracture Toughness (KIC) Rotor Steel Using Charpy Absorbed Energy (CVN). Journal of Advanced Materials and Processing. 1(3): 11–7.
8. [8] Terán, G., Capula-Colindres, S., Angeles-Herrera, D., Velázquez, J.C., Fernández-Cueto, M.J., (2016). Estimation of fracture toughness KIC from Charpy impact test data in T-welded connections repaired by grinding and wet welding. Engineering Fracture Mechanics. 153(January 2018): 351–9. doi: 10.1016/j.engfracmech.2015.12.010.

9. [9] Takashima, Y., Ito, Y., Lu, F., Minami, F., (2019). Fracture toughness evaluation for dissimilar steel joints by Charpy impact test. Welding in the World. 63(5): 1243–54. doi: 10.1007/s40194-019-00752-x.
10. [10] Bianchi, K.E., Barbosa, V.S., Savioli, R., Fernandes, P.E.A., Ruggieri, C., (2017). Correlation of Fracture Toughness With Charpy Impact Energy for Low Alloy, Structural Steel Welds. Volume 6B: Materials and Fabrication, American Society of Mechanical Engineers p. 1–11.
11. [11] Zhou, Z., Huang, S., Hui, H., Zhang, Y., (2020). Estimation of Minimum Design Metal Temperature by MDMT Curve and Correlations of Charpy Impact and Fracture Toughness. Journal of Pressure Vessel Technology. 142(6). doi: 10.1115/1.4046888.
12. [12] Puppala, G., Moitra, A., Sathyanarayanan, S., Kaul, R., Sasikala, G., Prasad, R.C., et al., (2014). Evaluation of fracture toughness and impact toughness of laser rapid manufactured Inconel-625 structures and their co-relation. Materials and Design. 59: 509–15. doi: 10.1016/j.matdes.2014.03.013.
13. [13] Uğurlu, M., Çakan, A., (2019). The Effect of Tool Rotation Speed on Mechanical Properties of Friction Stir Spot Welded (FSSW) AA7075-T6 Aluminium Alloy Sheets. European Mechanical Science. 3(3): 97–101. doi: 10.26701/ems.520139.
14. [14] Şener, B., Akşen, T.A., Fırat, M., (2021). On the Effect of Through-Thickness Integration for the Blank Thickness and Ear Formation in Cup Drawing FE Analysis 5: 51–5.
15. [15] BOLAT, Ç., AKGÜN, İ.C., GÖKSENLİ, A., (2020). On the Way to Real Applications: Aluminum Matrix Syntactic Foams. European Mechanical Science. 4(3): 131–41. doi: 10.26701/ems.703619.
16. [16] Yildiz, R.A., Yilmaz, S., (2020). Stress–Strain Properties of Artificially Aged 6061 Al Alloy: Experiments and Modeling. Journal of Materials Engineering and Performance. 29(9): 5764–75. doi: 10.1007/s11665-020-05080-6.
17. [17] Hoffman, C.R., (1980). INTERPRETIVE REPORT ON SMALL-SCALE TEST CORRELATIONS WITH FRACTURE TOUGHNESS DATA. Lehigh University, (1980).
18. [18] Kleinberg, A., Grugan, B., Greene, K., Benzing, B., Schroeder, J., Bruce Vieth, M., et al., (1986). Fracture Mechanics Evaluation of Irradiation Embrittlement in Reactor Vessel Steels Based on the Rate Process Concept. Journal of Testing and Evaluation. 14(1): 40. doi: 10.1520/JTE10319J.
19. [19] Rao, B.N., Acharya, A.R., (1989). Charpy V-notch impact test: A partial alternate to ASTM E 399 fracture testing for routine quality control applications. Engineering Fracture Mechanics. 32(1): 39–42. doi: 10.1016/0013-7944(89)90204-X.
20. [20] Sailors, R., Corten, H., (1972). Relations between material fracture toughness using fractures mechanics and transition temperature test. National Symposium on Fracture Mechanics, p. 164–91.
21. [21] Marandet, B., Sanz, G., n.d. Evaluation of the Toughness of Thick Medium-Strength Steels by Using Linear-Elastic Fracture Mechanics and Correlations Between. Flaw Growth and Fracture, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959: ASTM International p. 72-72–24.
22. [22] Roberts, R., Newton, C., (1984). Report on small-scale test correlations with KIC data. New York, NY: Welding Research Council.
23. [23] Kussmaul, K., Roos, E., (1985). Statistical evaluation of post-yield fracture mechanics properties on the basis of the notched bar impact test. Nuclear Engineering and Design. 87: 123–37. doi: 10.1016/0029-5493(85)90101-3.
24. [24] Lucon, E., Langenberg, P., Wallln, K., Pisarski, H., (2005). The use of Charpy/fracture toughness correlations in the FITNET procedure. Proceedings of the International Conference on Offshore Mechanics and Arctic Engineering - OMAE. 3(Omae): 365–8. doi: 10.1115/OMAE2005-67569.
25. [25] Li, X., Song, Y., Ding, Z., Bao, S., Gao, Z., (2018). A modified correlation between KJIC and Charpy V-notch impact energy of Chinese SA508-III steel at the upper shelf. Journal of Nuclear Materials. 505: 22–9. doi: 10.1016/j.jnucmat.2018.03.056.
26. [26] ASTM., (2009). Standard Test Methods for Tension Testing of Metallic Materials.
27. [27] ASTM International., (2018). ASTM E23 − 18, Standard Test Methods for Notched Bar Impact Testing of Metallic Materials. ASTM International.: 1–26. doi: 10.1520/E0023-18.
28. [28] Materials, T., Company, I., n.d. ASM Handbook Volume 04: Heat Treating.
29. [29] Xing, M. zhi., Wang, Y. gang., Jiang, Z. xiu., (2013). Dynamic Fracture Behaviors of Selected Aluminum Alloys Under Three-point Bending. Defence Technology. 9(4): 193–200. doi: 10.1016/j.dt.2013.11.002.
30. [30] MacMaster, F.J., Chan, K.S., Bergsma, S.C., Kassner, M.E., (2000). Aluminum alloy 6069 part II: Fracture toughness of 6061-T6 and 6069-T6. Materials Science and Engineering A. 289(1–2): 54–9. doi: 10.1016/S0921-5093(00)00918-7.
31. [31] Wang, Y.G., Jiang, Z.X., Wang, L.L., (2013). Dynamic tensile fracture behaviours of selected aluminum alloys under various loading conditions. Strain. 49(4): 335–47. doi: 10.1111/str.12040.