Document Type : Original Article


1 Department of Mechanical Engineering, Ferdowsi University of Mashhad, Iran

2 Department of Material Engineering, Birjand University of Technology, Birjand, Iran

3 Department of Civil Engineering, Shahrood University of Technology, Iran


In the present study Charpy impact tests on a 7075-T651 aluminium alloy with full size (55×10×10 mm) with different notch tip radius (range of 0.19 to 0.40 mm) were conducted and the fracture energy was measured. The experimental results showed that the relationship between the fracture energy (E) and the notch tip radius of the Charpy samples (r) for the tested Aluminium is E=18.052r+1.741. Using this relationship, the Charpy energy can be determined for this Aluminium for any notch tip radius. Fracture surfaces revealed an intergranular failure for base metal in longitudinal direction, that a predominately brittle failure (cleavage) with some insights of ductile characteristics was observed. Moreover, with increasing notch tip radius, cracked particles were observed and some microvoids were nucleated, i.e., ductile fracture. Changes in the primary crack notch cause a change in the stress intensity factor adjacent to the crack tip, where the fracture energy in the Charpy Impact Test is subjected to the primary crack notch.


[1]     Dieter, G. E., Mechanical Metallurgy, McGraw-Hill Book, New York, 1988.
[2]     Meyers, M. A., Chawla, K. K., Mechanical Behavior of Materials, Prentice Hall, New Jersey, 1999.
[3]     Druce, S. G., Gage, G., and Popkiss, E., Effects of Notch Geometry on the Impact Fracture Behaviour of a Cast Duplex Stainless Steel, Materials Physics and Metallurgy Division, Harwell Laboratory, UKAEA, Oxfordshire, OX11 0RA, UK, 1987.
[4]     Lukas, P., Kunz, L., Weiss, B., and Stickler, R., Notch Size Effect in Fatigue, Fatigue and Fracture of Engineering Materials and Structures, Vol. 12, No. 3, 1989, pp. 175-186.
[5]     Gomez, F. J., Elices, M., and Planas, J., The Cohesive Crack Concept: Application to PMMA at -60°, Departamento de Ciencia de Materiales, Universidad Polite´cnica de Madrid E.T.S. Ingenieros de Caminos, Spain, 2004.
[6]     Barati, E., Alizadeh, Y., and Aghazadeh, J., The Effect of Notch Depth and Notch Root Radius on the Averaged Strain Energy Density and on Fracture Load in U Notches under Bending, Aerospace Mechanics Journal, Vol. 5, No. 2, pp. 39-49, 2009. (in Persian)
[7]     Salavati, H., Alizadeh, Y., Effect of Notch Depth and Radius on the Critical Fracture Load of bainitic Functionally Graded Steels Under Mixed Mode I + II Loading, Physical Mesomechanics, Vol. 4, 2014.
[8]     Ramkumar, K. R., Bekele, H., and Sivasankaran, S., Experimental Investigation on Mechanical and Turning Behavior of Al 7075/x%wt. TiB2-1% Gr In Situ Hybrid Composite, Advances in Materials Science and Engineering, 2015,
[9]     Ambriz, R. R., Jaramillo, D., Garcia, C., and Curiel, F. F., Fracture Energy Evaluation on 7075-T651 Aaluminum Alloy Welds Determined by Instrumented Impact Pendulum, Transactions of Nonferrous Metals Society of China, Vol. 26, pp. 974, 983, 2016,
[10]  Cova, M., Nanni, M., and Tovo, R., Geometrical Size Effect in High Cycle Fatigue Strength of Heavywalled Ductile Cast Iron GJS400: Weakest Link vs Defect-Based Approach, Procedia Engineering, Vol. 74, pp. 101-104, 2014.
[11]  Hosseinzadeh, A., Hashemi, S .H., Experimental Investigation of Notch Depth Effect on Charpy Fracture Energy in API X65 Steel, ISME2018, 2018. (in persian)
[12]  Hosseinzadeh, A., Maraki, M. R., Emamverdi, A., and Sadidi, M., Experimental Investigation of Notch Depth Effect on Charpy Fracture Energy in Aluminum 7075, ISME2019, 2019. (in persian)
[13]  Emamverdi, A., Maraki, M. R., Sadidi, M., and Hosseinzadeh, A., Experimental Investigation of Notch Tip Radius Effect on Charpy Fracture Energy in Aluminum 7075, ISME2019, 2019. (in persian)
[14]  Maraki, M. R., Sadidi Emamverdi, A., and Hosseinzadeh A., Experimental Investigation of Notch Angle Effect on Charpy Fracture Energy in Aluminum 7075, ISME2019, 2019. (in persian)
[15]  Patil, Sh., Haneef, M., Microstructure Tensile Properties and Hardness Behavior of Al7075 Matrix Composites Reinforced with Graphene Nanoplatelets and Beryl Fabricated by Stir Casting Method, International Journal of Engineering and Advanced Technology (IJEAT), Vol. 9, No. 1, pp. 2249 – 8958, 2019.
[16]  Prema1, C. E., Suresh, S., Ramanan, G., and Sivaraj, M., Characterization Corrosion and Failure Strength an Analysis of Al7075 Influenced with B4C and Nano-Al2O3 Composite using Online Acoustic Emission, Materials Research Express, 2020.
[17]  Hosseinzadeh, A., Hashemi, S .H., Experimental and Numerical Investigation of Notch Depth Effect on Charpy Fracture Energy in API X65 Steel, Iranian Journal of Mechanical Engineering, 2020. (in persian)
[18]  He, C., Liu, Y., Dong, J., Wang, Q., Wagner, D., and Bathias, C., Fatigue Crack Initiation Behaviors Throughout Friction Stir Welded Joints in AA7075-T6 in Ultrasonic Fatigue, Int. Journal of Fatigue, Vol. 81, pp. 171–178, 2015.
[19]  ASTM E23, Standard Test Methods for Notched Bar Impact Testing of Metallic Materials, American Society for Testing and Materials, ASTM Standards, West Conshohocken, 2007.
[20]  Majidi, A., Hashemi, S. H., Study of Macroscopic Fracture Surface Characteristics of Spiral Welded API X65 Gas Transportation Pipeline Steel, Modares Mechanical Engineering, Vol. 17, No. 11, pp. 219-228, 2018.
[21]  Irwin, G., Krafft, J., Paris, P., and Wells, A., Basic Aspects of Crack Growth and Fracture, Naval Research Lab Washigton DC, 1967.
[22]  Alatorre, N., Ambriz, R. R, Nouressine, B., Amouche, A., Talha, A., and Jaramillo, D., Tensile Properties and Fusion Zone Hardening for GMAW and MIEA Welds of a 7075-T651 Aluminum alloy [J], Acta Metallurgica Sinica, Vol. 27, No. 4, pp. 697-704, 2014.