Surface Analysis after Shot Peening Processing of ENAW 7075 Aluminium

Abstract:

Shot peening has been a very important and well-known surface cold-hardening process applicable to various machine parts and tool surfaces for quite a long time since it improves fatigue strength and corrosion resistance of stressed surfaces. Hardening by shot peening provides, because of plastic deformation, an increase in hardness and induces compressive residual stresses in the thin surface layer, which reduces material fatigue and prevents the generation and propagation of cracks. The present paper reports of results of shot peening hardening of specimens made of 7075-T651 aluminium. They were surface-hardened by steel shots M170 with Almen hardening intensity of 8A and 12A respectively and by glass beads GP165 with Almen hardening intensity of 12A. The steel shots and glass beads had the same diameter but differed considerably in hardness and density. The surface condition after shot peening processing was assessed in terms of surface integrity, which establishes a relation between processing conditions and roughness state and hardened-layer depth supported by an analysis of residual-stress variations.

• Periodical: Materials Science Forum (Volume 589)
• Pages: 385-390
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.589.385
• Online since: June 2008
• Authors: Janez Grum, Uros Zupanc
• Keywords: AA7075, Residual Stress, Shot Peening, Surface Roughness (SR)

References

[1] Volker Schulze; Modern Mechanical Surface Treatment. WILEY-VCH Verlag, Weinheim. (2006).

[2] Liu, Hu, Barter, Sharp. The effectiveness of repairing fatigue damaged 7050 aluminium alloy using shot peening. Structural Integrity and Fracture International Conference (SIF`04), 2004, pp.241-247, Brisbane, Australia.

[3] Sharp, Clark. The effect of peening on the fatigue life of 7050 aluminium alloy. TSP, Vol. 16, Issue 4. (2003).

[4] Koehler. (1986). Influence of Shot Peening with Different Peening Materials on the Stress Corrosion and Corrosion Fatigue Behavior of a Welded AlZnMg-Alloy., Adv. in Surf. Treat. Tech. Vol. 3, pp.221-227 (Pergamon).

DOI: 10.1002/3527606580.ch35

[5] Shen, Han, Herrera, Atluri. Assessment, development, and validation of computational fracture mechanics methodologies and tools for shot-peened materials. Final Report. DOT/FAA/AR-03/76. (2004).

[6] Shot Peening Applications, 8th Edition, Metal Improvement Company, (2005).

[7] George, Pillai, Shah. Optimization of shot peening parameters using Taguchi technique. J. of Mat. Proc. Techn. 153-154, 2004, pp.925-930.

DOI: 10.1016/j.jmatprotec.2004.04.159

[8] Benedetti, Bortolamedi, Fontanari, Frendo. Bending fatigue behaviour of differently shot peened Al 6082 T5 alloy. Int. J. Fatigue Vol. 26, 2004, pp.889-897.

DOI: 10.1016/j.ijfatigue.2003.12.003

[9] Guagliano. Relating Almen intensity to residual stresses induced by shot peening: a numerical approach. Mat. Proc. Tech. Vol. 110, 2001, pp.277-286.

DOI: 10.1016/s0924-0136(00)00893-1

[10] Wagner. (1999). »Mechanical surface treatments on titanium, aluminum and magnesium alloys. « Materials Science and Engineering Vol. A263 pp.210-216.

DOI: 10.1016/s0921-5093(98)01168-x

[11] ASTM Metals Handbook. (1972). »Atlas of microstructures of industrial alloys. « Vol 7. 8th edition. pp.242-272.

[12] ASTM E837-01 (E1) - Standard Test Method for Determining Residual Stresses by the Hole-Drilling Strain-Gage Method.

DOI: 10.1520/e0837-01e01