Impact of rim zone modifications on the surface finishing of ferritic–pearlitic 42CrMo4 using electrochemical machining. Issue 6 (1st February 2021)

• Record Type: Journal Article
• Authors: Zander, Daniela; Schupp, Alexander; Mergenthaler, Stefanie; Pütz, René D.; Altenbach, Christoph
• Is Part Of: Materials and corrosion. Volume 72:Issue 6(2021)
• Page Start: 995
• Page End: 1009
• Publication Date: 2021-02-01
• Subjects: 42CrMo4 steel -- electrochemical machining -- electrochemical simulation -- rim zone modifications -- surface finishing; Materials -- Periodicals; Metals -- Periodicals; Corrosion and anti-corrosives -- Periodicals; 620.1122305
• DOI: 10.1002/maco.202012213
• Languages: English
• ISSNs: 0947-5117

Abstract

Abstract: The efficiency of material removal using electrochemical machining (ECM) is highly dependent on the initial rim zone modifications of the material to be processed. The influence of the rim zone modifications, such as topography and microstructure, on ECM, is investigated on ferritic–pearlitic 42CrMo4 steel by experiment and simulation. 42CrMo4 steel in two different premachining states—ground and electric discharge machined (EDM)—is subjected to a subsequent surface finishing by ECM in sodium nitrate solution. Before and after ECM, the topography and microstructure are examined using scanning electron microscopy, X‐ray diffractometer, and topography analysis methods. The electrochemical properties of the material are determined by potentiodynamic polarization. The efficiency of surface finishing by ECM is quantified by mass spectroscopic analysis (inductively coupled plasma mass spectrometry) of the process electrolyte and related to the rim zone modifications by simulation. The results reveal that the efficiency of material removal during ECM is higher for EDM than for ground 42CrMo4. This is attributed to an increased roughness of EDM 42CrMo4 and to the unfavorable electrochemical properties of the cementite phase in ground 42CrMo4. Abstract : The rim zone properties of ferritic‐pearlitic 42CrMo4 steel significantly influence the efficiency of surface finishing by electrochemical machining (ECM). Experimental investigations and FEM simulations have shown that the roughness of the surface as well as the microstructure have a substantial impact on the efficiency of ECM. Increased surface roughness favors metal dissolution, while an increasing proportion of cementite in the microstructure reduces efficiency by promoting the development of oxygen.