The fatigue properties of thermo-mechanically treated and machined aluminum alloy 7475-T7351 have been studied. The applied advanced machining strategy induced intensive plastic deformation on the machined surface under defined cutting conditions. Therefore, a detailed study of 3D surface topography was performed. Advanced characterization of the material structure and electron back scattered diffraction mapping of selected chemical phases were performed, as well as energy dispersive X-ray analysis of the surface. Advanced mechanical properties of the material were investigated in situ with a scanning electron microscope that was equipped with a unique tensile fixture. The fatigue results confirmed an evident dispersion of the data, but the mechanism of crack nucleation was established. Fracture surface analysis showed that the cracks nucleated at the brittle secondary particles dispersed in the material matrix. The surface topography of samples that had been machined in wide range of cutting/deformation conditions by milling has not proved to be a decisive factor in terms of the fatigue behavior. The incoherent interface and decohesion between the alumina matrix and the brittle secondary phases proved to significantly affect the ultimate strength of the material. Tool engagement also affected the fatigue resistance of the material.

Central European Institute of Technology Brno University of Technology Brno 612 00 Czech Republic

Department of Manufacturing Technology Faculty of Mechanical Engineering Brno University of Technology 616 69 Brno Czech Republic

TESCAN ORSAY HOLDING a s 623 00 Brno Czech Republic

Zobrazit více v PubMed

Dietrich Altenpohl G. Aluminium: Technology, Application, and Environment, a Profile of a Modern Metal. 6th ed. Wiley-TMS; Washington, DC, USA: Weinheim, Germany: 1999. p. 319.

Verma B.B., Atkinson J.D. Study of fatigue behaviour of 7475 aluminium alloy. Bull. Mater. Sci. 2001;24:231–236. doi: 10.1007/BF02710107. DOI

Static and Dynamic Fracture Properties for Aluminum 7475 T7351: Final Report. Ohio. [(accessed on 1 October 2019)];1975 Available online: http://www.dtic.mil/dtic/tr/fulltext/u2/a014353.pdf.

Alloy 7475 Plate and Sheet. [(accessed on 1 October 2019)]; Available online: https://www.spacematdb.com/spacemat/manudatasheets/alloy7475techplatesheet.

Kunčická L., Terry C.L., Casey F.D., Kocich R., Pohludka M. Synthesis of an Al/Al2O3 composite by severe plastic deformation. Mater. Sci. Eng. A. 2015;646:234–241. doi: 10.1016/j.msea.2015.08.075. DOI

Naizabekov A.B., Andreyachshenko V.A., Kocich R. Study of deformation behavior, structure and mechanical properties of the AlSiMnFe alloy during ECAP-PBP. Micron. 2013;44:210–217. doi: 10.1016/j.micron.2012.06.011. PubMed DOI

Kunčická L., Kocich R., Ryukhtin V., Cullen J.C.T., Lavery N.P. Study of structure of naturally aged aluminium after twist channel angular pressing. Mater. Charact. 2019;152:94–100. doi: 10.1016/j.matchar.2019.03.045. DOI

Kocich R., Kunčická L., Král P., Macháčková A. Sub-structure and mechanical properties of twist channel angular pressed aluminium. Mater. Charact. 2016;119:75–83. doi: 10.1016/j.matchar.2016.07.020. DOI

Kunčická L., Kocich R. IOP Conference Series-Materials Science and Engineering. Volume 369 Curran Associates, Inc.; Red Hook, NY, USA: 2018. Deformation behaviour of Cu-Al clad composites produced by rotary swaging. In 5th global conference on polymer and composite materials (PCM 2018)

DeGarmo E., Black J., Kohser R. Materials and Processes in Manufacturing. 8th ed. Prentice Hall; Upper Saddle River, NJ, USA: 1997.

Humár A., Technologie I. Technologie Obrábění-1.Část-Studijní Opory pro Magisterskou Formu Studia. [(accessed on 1 October 2019)];2003 :138. Available online: http://ust.fme.vutbr.cz/obrabeni/opory-save/TI_TO-1cast.pdf.

Beńo J. Teória Rezania Kovov. Strojnická Fakulta TU Košice; Košice, Slovakia: 1999.

Driensky D., Fúrik P., Lehmanová T. Strojní Obrábění I. 1. SNTL; Prague, Czech Republic: 1986. p. 424.

Kunčická L., Kocich R., Dvořák K., Macháčková A. Rotary swaged laminated Cu-Al composites: Effect of structure on residual stress and mechanical and electric properties. Mater. Sci. Eng. A. 2019;742:743–750. doi: 10.1016/j.msea.2018.11.026. DOI

Kunčická L., Kocich R., Strunz P., Macháčková A. Texture and residual stress within rotary swaged Cu/Al clad composites. Mater. Lett. 2018;230:88–91. doi: 10.1016/j.matlet.2018.07.085. PubMed DOI

Broek D. Elementary Engineering Fracture Mechanics. Springer; Dordrecht, The Netherlands: 1986.

Ojolo S.J., Orisaleye I.J., Obiajulu N. Machining Variables Influence on the Fatigue Life of End-Milled Aluminium Alloy. Int. J. Mater. Sci. Appl. 2014;3:391–938.

Novovic D., Dewes D.K., Aspinwal W. The Effect of Machined Topography and Integrity on Fatigue Life. Int. J. Mach. Tools Manuf. 2004;44:125–134. doi: 10.1016/j.ijmachtools.2003.10.018. DOI

Koster W. Effect of Residual Stress on Fatigue of Structural Alloys; Proceedings of the Third International Conference, ASM International; Indianapolis, IN, USA. 15–17 May 1991.

Piska M., Ohnistova P., Hornikova J., Hervoches C. A study of progressive milling technology on surface topography and fatigue properties of the high strength aluminum alloy 7475-T7351; Proceedings of the 17th International Conference on New Trends in Fatigue and Fracture; Cancún, Mexico. 25–27 October 2017; New York City, NY, USA: Springer International Publishing AG; pp. 7–19.

Chemin A., Marques D., Bisanha L., Motheo A.J., Filho W.W.B., Ruchert C.O.F. Influence of Al7Cu2Fe intermetallic particles on the localized corrosion of high strength aluminum alloys. Mater. Des. 2014;53:118–123. doi: 10.1016/j.matdes.2013.07.003. DOI

Davis J.R. Aluminum and Aluminum Alloys. ASM International; Ohio, MI, USA: 1993. pp. 351–416. Illustrated Edition.

Priya P., Johnson D.R., Krane M.J.M. Precipitation during cooling of 7XXX aluminum alloys. Comput. Mater. Sci. 2017;139:273–284. doi: 10.1016/j.commatsci.2017.08.008. DOI

The Magazine about Alicona-Metrology [(accessed on 20 October 2019)];Alicona Focus Variation. (8th ed.). Available online: https://irp-cdn.multiscreensite.com/ebc29cc1/files/uploaded/Alicona_FOCUSvariation_magazine_2018_EN.pdf. (In English)

ISO 25178-606:2015, Geometrical product specification (GPS) - Surface texture: Areal Part 606: Nominal characteristics of non-contact (focus variation) instruments. ISO copyright office; Geneva, Switzerland: Jun 15, 2015.

ASTM E466–15, Standard Practice for Conducting Force Controlled Constant Amplitude Axial Fatigue Tests of Metallic Materials. ASTM International; West Conshohocken, PA, USA: May 1, 2015.

DIN EN 6072, Aerospace series - Metallic materials - Test methods - Constant amplitude fatigue testing. German Institute for Standardisation; Berlin, Germany: Jan 1, 2011.

3D Functional Parameters. [(accessed on 1 October 2019)]; Available online: https://www.michmet.com/3d_s_functional_parameters.htm.

Shankar M.R., Chandrasekar S., Compton W.D., King A.H. Characteristics of aluminum 6061-T6 deformed to large plastic strains by machining. Mater. Sci. Eng. 2005;410–411:364–368. doi: 10.1016/j.msea.2005.08.137. DOI

Special Issue: Mechanical Properties in Progressive Mechanically Processed Metallic Materials