Abstract
Machining the EN X160CrMoV12 tool steel by electro-discharge machining (EDM) process generates significant modifications of microgeometrical, microstructural and mechanical properties of the upper layers of the machined components. In this paper, the role of these modifications in controlling the stability, under cyclic loading, of the propagation of the crack networks generated by EDM is discussed. High cycle fatigue tests (2 × 106 cycles) show that the presence of these cracks in brittle layers, i.e. white layer, quenched the martensitic layer, and a field of tensile residual stresses (+750 MPa) results in a loss of 34% of endurance limit comparatively with the endurance evaluated for the milled state that generates crack-free surfaces. It is shown, in this work, that the detrimental effect of these crack networks can be controlled by putting in compression the upper layers of the EDM surfaces. Indeed the application of wire brushing to EDM surfaces generates compressive residual stresses (≈−100 MPa) that stabilise the crack networks propagation and therefore restores to the EDM surfaces their endurance limit value corresponding to the milled state. Moreover, removing the crack networks by polishing generates a stabilised residual stress value of ≈−130 MPa. This results in an improvement rate of about 70% of the endurance limit comparatively with the EDM state and of 26% in comparison to the milled state. These rates could be further increased by the application of the wire brushing process to the polished surfaces that reached 75% and 30% comparatively to the EDM and milling states respectively. In this case, a stabilised surface residual stress of about ≈−150 MPa was measured on the specimen surfaces.
Article PDF
Similar content being viewed by others
Avoid common mistakes on your manuscript.
References
Ho KH, Newman ST (2003) State of the art electrical discharge machining (EDM). Int J Mach Tools Manuf 43:1287–130
Yeo SH, Kurnia W, Tan PC (2008) Critical assessment and numerical comparison of electro-thermal models in EDM. J Mater Process Technol 203:241–251
Ghanem F, Atig KB, Salah NB, Braham C (2007) Prédiction par calcul de la rugosité totale d’une surface usinée par électroérosion. Matériaux et Techniques 94:419–428
Ghanem F, Braham C, Sidhom H (2003) Influence of steel type on electrical discharge machined surface integrity. J Mater Process Technol 142:163–173
Ghanem F, Fredj N B, Sidhom H, Braham C (2003) Influence du mode de fraisage sur l’intégrité de surface et la tenue en fatigue des pièces usinées, SF2M ,22èmes Journées de Printemps, Commission de Fatigue, CETIM Senlis, 21 and 22 May 2003
Hiong LS, Xiaoping L (2003) Study of the surface integrity of the machined workpiece in the EDM of tungsten carbide. J Mater Process Technol 139:315–321
Choi KK, Nam WJ, Lee YS (2008) Effects of heat treatment on the surface of a die steel STD11 machined by W-EDM. J Mater Process Technol 201:580–584
Ghanem F, Braham C, Fitzpatrick ME, Sidhom H (2002) Effect of near-surface residual stress and microstructure modification from machining on the fatigue endurance of tool steel. J Mater Eng Perform 11:631–639
Grosch J (1989) Einfluβ der funkenerosiven Bearbeitung auf das Randgefüge verschiedener Stähle. HTM 44:290–295
Tadao T, Takeo T (1987) Effect of the electro-discharge machined surface on the mechanical properties. Bull Japan Soc of Prec Engg 21(N°1):70–71
Kisuke I, Katsuji T (1988) Fatigue strength of shot penned specimen formed by laser cutting and wire EDM. Bull Japan Soc of Prec Engg 22(N°3):195–199
Walbank J (1980) Wear of spark-eroded (EDM) brass stamping dies. Metallurgia 47(1):4–6
Hocheng H, Lei W, Hsu HS (1997) Preliminary study of material removal in electrical-discharge machining of SiC/Al. J Mater Process Technol 63(1–3):813–818
Fordham JD, Pilkington R, Tangt CC (1997) The effect of different profiling techniques on the fatigue performance of metallic membranes of AISI 301 and Inconel 718. Int J Fatigue 19:487–501
AGIE (1987) Controlling EDM surface integrity. American Machinist and Automated Manufacturing 81–83
Guu YH, Hocheng H (2001) Improvement of fatigue life of electrical discharge machined AISI D2 tool steel by TiN coating. Mater Sci Eng, A 318:155–162
Yan BH, Lin YC, Huang FY (2002) Surface modification of Al–Zn–Mg alloy by combined electrical discharge machining with ball burnish machining. Int J Mach Tools Manuf 42:925–934
Wang ZL, Fang Y, Wu PN, Zhao WS, Cheng K (2002) Surface modification process by electrical discharge machining with a Ti powder green compact electrode. J Mater Process Technol 129:139–142
Cheng LY, Hwa BY, Song YC (2000) Machining characteristics of titanium alloy (Ti–6Al–4V) using a combination process of EDM with USM. J Mater Process Technol 104:171–177
Fredj NB, Nasr MB, Rhouma AB, Braham C, Sidhom H (2004) Fatigue life improvements of the AISI 304 stainless steel ground surfaces by wire brushing. J Mater Eng Perform 13:564–574
Novovie D, Dewes RC, Aspinwall DK, Voice W, Bowen P (2004) The effect of machined topography and integrity on fatigue life. Int J Mach Tools Manuf 44:125–134
Ataollah J, Ulfried R, Wilfried E (2008) The effect of machining on the surface integrity and fatigue life. Int J Fatigue 30:2050–2055
Sheng-Kuei L, Yung-Li L, Ming-Wei L (2001) Evaluation of the staircase and the accelerated test methods for fatigue limit distribution. Int J Fatigue 23:75–83
Peças P, Henriques E (2008) Electrical discharge machining using simple and powder-mixed dielectric: the effect of the electrode area in the surface roughness and topography. J Mater Process Technol 200:250–258
Lemaitre J, Chaboche J-L (1990) Mechanics of solid materials. Cambridge University Press, UK
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Ghanem, F., Fredj, N.B., Sidhom, H. et al. Effects of finishing processes on the fatigue life improvements of electro-machined surfaces of tool steel. Int J Adv Manuf Technol 52, 583–595 (2011). https://doi.org/10.1007/s00170-010-2751-y
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s00170-010-2751-y