Strength Prediction of Lamellar Graphite Iron: From Griffith’s to Hall-Petch Modified Equation

Abstract:

Traditionally, ultimate tensile strength (UTS) is used as the main property for the characterization of lamellar graphite iron (LGI) alloys under static loads. The main models found in the literature for predicting UTS of pearlitic lamellar graphite iron are based on either regression analysis on experimental data or on modified Griffith or Hall-Petch equation.In pearlitic lamellar graphite iron the primary austenite dendritic network, transformed to pearlite, reinforces the bulk material while the distance between those pearlite grains, defines the maximum continuous defect size in the bulk material. Recently the novel parameter of the Diameter of Interdendritic Space has been used to express the flow length in a modified Griffith equation for the prediction of the UTS in LGI. Nevertheless this model neglects the strengthening effect of the pearlite lamellar spacing within the perlite grains. A model based on modified Hall-Petch equation was developed in this work. The model considers the effect of both microstructure parameters and covers a broad spectrum of microstructure sizes typical for complex shape castings with various wall thicknesses.

• Periodical: Materials Science Forum (Volume 925)
• Pages: 272-279
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.925.272
• Online since: June 2018
• Authors: Vasilios Fourlakidis*, Lucian Vasile Diaconu, Attila Diószegi
• Keywords: Lamellar Graphite Iron, Pearlite Spacing, Primary Austenite, Tensile Strength

References

[1] L. Collini, G. Nicoletto, R. Konecná, Microstructure and mechanical properties of pearlitic lamellar cast iron, Mat Sci Eng A - Struct 488 (2008) 529-539.

DOI: 10.1016/j.msea.2007.11.070

[2] G.F. Ruff, J.F. Wallace, Effects of solidification structure on the tensile properties of lamellar iron, AFS Transactions 56 (1977) 179-202.

[3] C. Bates, Alloy element effect on lamellar iron properties: part II, AFS Trans. 94 (1986) 889-905.

[4] H. Nakae, H. Shin, Effect of graphite morphology on tensile properties of flake graphite cast iron, Mater Trans 42 (2001) 1428-1434.

DOI: 10.2320/matertrans.42.1428

[5] T.J. Baker, The fracture resistance of the flake graphite cast iron, Materials in Engineering Applications 1 (1978) 13-18.

DOI: 10.1016/0141-5530(78)90003-1

[6] D.D. Goettsch and J.A. Dantzig, Modeling microstructure development in gray cast irons, Metall Mater Trans A, 25 (1994), 1063–1079.

DOI: 10.1007/bf02652281

[7] V. Fourlakidis and A. Diószegi, A generic model to predict the ultimate tensile strength in pearlitic lamellar graphite iron, Mat Sci Eng A – Struct 618 (2014) 161–167.

DOI: 10.1016/j.msea.2014.08.061

[8] D.A. Porter and K.E. Easterling, Dynamic studies of the tensile deformation and fracture of pearlite, Acta Metall 26 (1978), 1405-1422.

DOI: 10.1016/0001-6160(78)90156-6

[9] A. Catalina, X. Guo, D.M. Stefanescu, L. Chuzhoy, M.A. Pershing, Prediction of room temperature microstructure and mechanical properties in lamellar iron castings, AFS Trans. 94 (2000) 889-912.

[10] A. Diószegi, V. Fourlakidis, I.L. Svensson, Fracture mechanics of lamellar cast iron, Solidification and Gravity V, Trans Tech Publications, Switzerland, Materials Science Forum 649 (2010), 517-522.

DOI: 10.4028/www.scientific.net/msf.649.517

[11] A. Diószegi, V. Fourlakidis, R. Lora, Austenite Dendrite Morphology in Lamellar Cast Iron, Int J Cast Metal Res, 28(Issue 5) (2015), 310-317.

DOI: 10.1179/1743133615y.0000000018