The Effect of Interlamellar Distance in Pearlite on CGI Machining

Authors: Anders Berglund, Cornel Mihai Nicolescu, Henrik Svensson

Abstract:

Swedish truck industry is investigating the possibility for implementing the use of Compacted Graphite Iron (CGI) in their heavy duty diesel engines. Compared to the alloyed gray iron used today, CGI has superior mechanical properties but not as good machinability. Another issue that needs to be addressed when implementing CGI is the inhomogeneous microstructure when the cast component has different section thicknesses, as in cylinder blocks. Thinner sections results in finer pearlite, in the material, with higher strength. Therefore an investigation on its influence on machinability was needed. This paper focuses on the effect that interlamellar distance in pearlite has on CGI machinability and material physical properties. The effect of pearlite content and nodularity is also examined. The results showed that interlamellar distance in pearlite did not have as large effect on the material physical properties or machinability as pearlite content. The paper also shows the difficulties of obtaining a homogeneous microstructure in inhomogeneous workpieces.

Keywords: Compacted graphite iron (CGI), machinability, microstructure, milling, interlamellar distance in pearlite.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1080828

References:

[1] S. Dawson and T. Schroeder, "Practical Applications for Compacted Graphite Iron," in Transactions of the American Foundry Society and the One Hundred Eigth Annual Metalcasting Congress, Rosemont, USA, 2004, pp. 813-821.
[2] W. Guesser, T. Schroeder, and S. Dawson, "Production Experience With Compacted Graphite Iron Automotive Components," in AFS Transactions 01-071, 2001, Reprinted from 2001 AFS Transactions.
[3] L. Collini, G. Nicoletto, and R. Konecná, "Microstructure and mechanical properties of pearlitic gray cast iron," Materials science and engineering A, vol. 488, pp. 529-539, 2008.
[4] G. M. Goodrich, Iron Castings Engineering Handbook. Schaumburg, USA: American Foundery Society, 2006.
[5] C. Heisser and J. C. Strum, "Casting Process Simulation of Compacted Graphite Iron (03-025)," in Transaction of hte American Foundry Society and the One Hundred Seventh Annual Casting Congress, Milwaukee, 2003, pp. 685-692.
[6] A. Berglund and C. M. Nicolescu, "Investigation of the effect of microstructure on CGI machining," in Swedish Production Symposium, Gothenburg, Sweden, 2007.
[7] A. Sahm, E. Abele, and H. Schultz, "Machining of Compacted Graphite Iron (CGI)," Materialwissenschaft und Werkstofftechnik, vol. 33, no. 9, pp. 501-506, Sep 2002.
[8] U. Reuter, Verschleissmechanismen bei der bearbeitung con gusseisen mit PCBN-schneidstoffen. Darmstadt, Germany: Darmstadt Techn. Univ., 2001, PhD Thesis.
[9] E. Abele, A. Sahm, and H. Schultz, "Wear Mechanism when Machining Compacted Graphite Iron," CIRP Annals - Manufaturing Technology, vol. 51, no. 1, pp. 53-56, 2002.
[10] I. Sadik, "The Interaction between Cutting Data and Tool Performance for different Cutting Tool Material in Milling of Compacted Graphite Iron," in Sixth International Conference on High Speed Machining 2007, 2007.
[11] A. Berglund, Characterization of factors interacting in CGI machining. Stockholm, Sweden: Royal Institute of Technology, Production Engineering, 2008, Licentiate Thesis.
[12] S. Dawson et al., "The Effect of Metallurgical Variables on the Machinability of Compacted Graphite Iron," in SAE 2001 World congress, Detroit, 2001, pp. 4-16.
[13] R. E. Showman and R. C. Aufderheide, "Controlling Nodularity in Thin- Wall Compacted Graphite Iron Castings," in Transactions of the American Foundry Society and the One Hundred Eigth Annual Metalcasting Congress, Rosemont, Il, USA, 2004, pp. 823-829.
[14] S. Kim, S.L. Cockcroft, and A.M. Omran, "Optimization of the process parameters affecting the microstructures and properties if compacted graphite iron (article in press)," Journal of Alloys and compounds, 2008.
[15] A. Berglund and M. Näslund, Skärbarheten hos Kompaktgrafitjärn. Stockholm, Sweden: Royal Institute of Technology, Production Engineering, 2006, Master Thesis.
[16] F. Mampaey, "Prediction of gray iron tensile strength by the separation of variables," AFS Transaction, vol. 97, pp. 879-897, 2004.