A Preliminary Geometrical Characterization of Surface Scratches on Aluminium Alloys Used in the Aerospace Industry

Abstract:

Surface marks, such as scratches or cosmetic marks, commonly appear during the manufacturing phase of metallic components, because of the contact between tools and sharp edges with the surface of the parts. Scratches, depending on their width, depth, and root radius, cause a decrease in the fatigue life of metallic alloys. In particular, the presence of scratches with a size comparable to the grain size favors the generation of fatigue cracks in these features. In the aerospace industry, the presence of surface marks is a common cause of rejection. The low hardness of aluminium, a material widely employed in the manufacture of aerospace structures, contributes to the generation of surface marks. In this paper, a preliminary geometrical characterisation of scratches is established. It aims to define a set of parameters to characterise exhaustively the different scratches and to generate different behavior models for each type of scratch. Parameters such as scratch length, path radius, and burr height are considered in addition to the well-known parameters such as scratch depth, root radius, and open angle.

• Periodical: Key Engineering Materials (Volume 955)
• Pages: 73-80
• DOI: https://doi.org/10.4028/p-JxYsS4
• Online since: September 2023
• Authors: Guzman Domínguez-Domínguez, Fernando Mas*, Carpoforo Vallellano
• Keywords: Aerospace, Aluminium, Manufacturing, Model, Scratches

References

[1] Zerbst, U.; Madia, M.; Klinger, C.; Bettge, D.; Murakami, Y. Defects as a Root Cause of Fatigue Failure of Metallic Components. III: Cavities, Dents, Corrosion Pits, Scratches, Engineering Failure Analysis. 97 (2019) 759–776.

DOI: 10.1016/j.engfailanal.2019.01.034

[2] Zhan, Z.; Hu, W.; Zhang, M.; Meng, Q. The Fatigue Life Prediction for Structure with Surface Scratch Considering Cutting Residual Stress, Initial Plasticity Damage and Fatigue Damage, International Journal of Fatigue 74 (2015) 173–182.

DOI: 10.1016/j.ijfatigue.2015.01.011

[3] Zhan, Z.; Hu, W.; Meng, Q.; Guan, Z. Fatigue Life and Defect Tolerance Calculation for Specimens with Foreign Object Impact and Scratch Damage, Arch Appl Mech. 88 (2018) 373–390.

DOI: 10.1007/s00419-017-1313-2

[4] Lazzeri, L.; Mariani, U. Application of Damage Tolerance Principles to the Design of Helicopters. International Journal of Fatigue. 31 (2009) 1039–1045.

DOI: 10.1016/j.ijfatigue.2008.05.010

[5] Varga, M.; Leroch, S.; Gross, T.; Rojacz, H.; Eder, S.J.; Grillenberger, M.; Rodríguez Ripoll, M. Scratching Aluminium Alloys – Modelling and Experimental Assessment of Damage as Function of the Strain Rate. Wear 476 (2021) 203670.

DOI: 10.1016/j.wear.2021.203670

[6] Heinrichs, J.; Jacobson, S. The Influence from Shape and Size of Tool Surface Defects on the Occurrence of Galling in Cold Forming of Aluminium, Wear. 271 (2011) 2517–2524.

DOI: 10.1016/j.wear.2011.01.077

[7] Cini, A.; Irving, P.E. Development of Fatigue Cracks from Mechanically Machined Scratches on 2024-T351 Aluminium Alloy-Part I: Experimentation and Fractographic Analysis: Development of Fatigue Cracks from Mechanically Machined Scratches-Part I. Fatigue Fract Engng Mater Struct. 40 (2017) 776–789.

DOI: 10.1111/ffe.12544

[8] Ding, M.C.; Zhang, Y.L.; Lu, H.T. Fatigue Life Prediction of TC17 Titanium Alloy Based on Micro Scratch. International Journal of Fatigue. 139 (2020) 105793.

DOI: 10.1016/j.ijfatigue.2020.105793

[9] Khan, M.K.; Fitzpatrick, M.E.; Hainsworth, S.V.; Edwards, L. Effect of Tool Profile and Fatigue Loading on the Local Hardness around Scratches in Clad and Unclad Aluminium Alloy 2024. Materials Science and Engineering: 527 (2009) 297–304.

DOI: 10.1016/j.msea.2009.07.035

[10] Zhuang, W.Z.; Halford, G.R. Investigation of Residual Stress Relaxation under Cyclic Load, International Journal of Fatigue. 23 (2001) 31–37.

DOI: 10.1016/s0142-1123(01)00132-3

[11] Webster, G.A.; Ezeilo, A.N. Residual Stress Distributions and Their Influence on Fatigue Lifetimes. International Journal of Fatigue. 23 (2001) 375–383.

DOI: 10.1016/s0142-1123(01)00133-5

[12] Nowell, D.; Dini, D.; Duó, P. Stress Analysis of V-Notches with and without Cracks, with Application to Foreign Object Damage. The Journal of Strain Analysis for Engineering Design. 38 (2003) 429–441.

DOI: 10.1243/03093240360713487

[13] Zhao, Y.X.; Irving, P.E.; Cini, A. Hardness Environments around Fatigued Scratches in Clad and Unclad 2024 T351 Aluminium Alloy. Materials Science and Engineering: A 2009, 500, 16–24.

DOI: 10.1016/j.msea.2008.09.039

[14] Inchekel, A.; Talia, J.E. Effect of Scratches on the Fatigue Behaviour of an Al-Li alloy, Fatigue & Fracture of Engineering Materials & Structures. 17 (1994) 501–507.

DOI: 10.1111/j.1460-2695.1994.tb00250.x

[15] Abroug, F.; Pessard, E.; Germain, G.; Morel, F. HCF of AA7050 Alloy Containing Surface Defects: Study of the Statistical Size Effect, International Journal of Fatigue. 110 (2018) 81–94.

DOI: 10.1016/j.ijfatigue.2018.01.012

[16] Lorenzino, P.; Navarro, A. Grain Size Effects on Notch Sensitivity. International Journal of Fatigue. 70 (2015) 205–215.

DOI: 10.1016/j.ijfatigue.2014.09.012

[17] Vincent, M.; Nadot, Y.; Nadot-Martin, C.; Dragon, A. Interaction between a Surface Defect and Grain Size under High Cycle Fatigue Loading: Experimental Approach for Armco Iron, International Journal of Fatigue. 87 (2016) 81–90.

DOI: 10.1016/j.ijfatigue.2016.01.013

[18] Vallellano, C.; Mariscal, M.R.; Navarro, A.; Dominguez, J. A Micromechanical Approach to Fatigue in Small Notches. Fat Frac Eng Mat Struct 2005, 28, 1035–1045.

DOI: 10.1111/j.1460-2695.2005.00942.x

[19] Cini, A.; Irving, P.E. Transformation of Defects into Fatigue Cracks; the Role of Kt and Defect Scale on Fatigue Life of Non-Pristine Components, Procedia Engineering. 2 (2010) 667–677.

DOI: 10.1016/j.proeng.2010.03.072

[20] Murakami, Y. Stress Concentration, in: Murakami, Y (Eds.), Metal Fatigue, Academic Press, 2019 p.13–27.

[21] Murakami, Y. Notch Effect and Size Effect, in: Murakami, Y (Eds.), Metal Fatigue, Academic Press, 2019 p.29–37.

DOI: 10.1016/b978-0-12-813876-2.00003-0

[22] Murakami, Y. Effect of Size and Geometry of Small Defects on the Fatigue Limit, in: Murakami, Y (Eds.), Metal Fatigue, Academic Press, 2019 p.39–59.

DOI: 10.1016/b978-0-12-813876-2.00004-2

[23] Paz Martínez-Viademonte, M.; Abrahami, S.T.; Hack, T.; Burchardt, M.; Terryn, H. A Review on Anodizing of Aerospace Aluminum Alloys for Corrosion Protection, Coatings. 10 (2020) 1106.

DOI: 10.3390/coatings10111106

[24] Nguyen, A.N.; Pébère, N. A Local Electrochemical Impedance Study of the Self-Healing Properties of Waterborne Coatings on 2024 Aluminium Alloy, Electrochimica Acta. 222 (2016) 1806-1817.

DOI: 10.1016/j.electacta.2016.11.152

[25] He, X.; Shi, X. Self-Repairing Coating for Corrosion Protection of Aluminum Alloys, Progress in Organic Coatings. 65 (2009) 37–43.

DOI: 10.1016/j.porgcoat.2008.09.003

[26] Jia, X.; Song, J.; Qu, X.; Cao, F.; Jiang, B.; Atrens, A.; Pan, F. Effect of Scratch on Corrosion Resistance of Calcium phosphate Conversion coated AZ80 Magnesium, Transactions of Nonferrous Metals Society of China. 32 (2022) 147-161.

DOI: 10.1016/s1003-6326(21)65784-9