Property enhancement of cast iron used for nuclear casks

Abstract

Ductile iron (DI) is a preferred material for use in various structural, automotive, and engineering fields because of its excellent combination of strength, toughness, and ductility. In the current investigation, we elucidate the relationship between the morphological and mechanical properties of DI intended for use in safety applications in the nuclear industry. DI specimens with various alloying elements were subjected to annealing and austempering heat treatment processes. A faster cooling rate appeared to increase the nodule count in austempered specimens, compensating for their nodularity value and subsequently decreasing their ductility and impact strength. The ductility and impact energy values of annealed specimens increased with increasing ferrite area fraction and nodularity, whereas an increase in the amounts of Ni and Cr resulted in an increase of hardness via solid solution strengthening. Austempered specimens were observed to be stronger than annealed specimens and failed in a somewhat brittle manner characterized by a river pattern, whereas the ductile failure mode was characterized by the presence of dimples.

Keywords

ductile iron / nodularity / mechanical properties / failure modes / nuclear industry

References

[1] Konečná R., Nicoletto G., Bubenko L., Fintová S. A comparative study of the fatigue behavior of two heat-treated nodular cast irons. Eng. Fract. Mech., 2013, 108, 251.

[2] Dommarco R.C., Sousa M.E., Sikora J.A. Abrasion resistance of high nodule count ductile iron with different matrix microstructures. Wear, 2004, 257(4): 1185.

[3] Rashidi A.M., Moshrefi-Torbati M. Effect of tempering conditions on the mechanical properties of ductile cast iron with dual matrix structure (DMS). Mater. Lett., 2000, 45(3-4): 203.

[4] Zhou R., Jiang Y.H., Lu D.H., Zhou R.F., Li Z.H. Development and characterization of a wear resistant bainite/ martensite ductile iron by combination of alloying and a controlled cooling heat-treatment. Wear, 2001, 250(1-12): 529.

[5] Martins R., Seabra J., Magalhães L. Austempered ductile iron (ADI) gears: Power loss. pitting and micropitting, Wear, 2008, 264(9-10): 838.

[6] Erić O., Jovanović M., Šidānin L., Rajnović D., Zec S. The austempering study of alloyed ductile iron. Mater. Des., 2006, 27(7): 617.

[7] Putatunda S.K., Kesani S., Tackett R., Lawes G. Development of austenite free ADI (austempered ductile cast iron). Mater. Sci. Eng. A, 2006, 435-436, 112.

[8] Murthy K.N., Sampathkumaran P., Seetharamu S. Abrasion and erosion behaviour of manganese alloyed permanent moulded austempered ductile iron. Wear, 2009, 267(9-10): 1393.

[9] El-Baradie Z.M., Ibrahim M.M., El-Sisy I.A., Abd El-Hakeem A.A. Austempering of spheroidal graphite cast iron. Mater. Sci., 2004, 40(4): 523.

[10] Murat B., Akray S.I. Successive boronizing and austempering for GGG-40 grade ductile iron. J. Iron Steel Res. Int., 2009, 16(2): 50.

[11] Ghaderi A.R., Nili Ahmadabadi M., Ghasemi H.M. Effect of graphite morphologies on the tribological behavior of austempered cast iron. Wear, 2003, 255(1-6): 410.

[12] Peng Y.C., Jin H.J., Liu J.H., Li G.L. Influence of cooling rate on the microstructure and properties of a new wear resistant carbidic austempered ductile iron (CADI). Mater. Charact., 2012, 72, 53.

[13] Putatunda S.K. Comparison of the mechanical properties of austempered ductile cast iron (ADI) processed by conventional and step-down austempering process. Mater. Manuf. Process., 2010, 25, 749.

[14] Peng Y.C., Jin H.J., Liu J.H., Li G.L. Effect of boron on the microstructure and mechanical properties of carbidic austempered ductile iron. Mater. Sci. Eng. A, 2011, 529, 321.

[15] Sidjanin L., Smallman R.E., Young J.M. Electron microstructure and mechanical properties of silicon and aluminium ductile irons. Acta Metall. Mater., 1994, 42(9): 3149.

[16] Elsayed A.H., Megahed M.M., Sadek A.A., Abouelela K.M. Fracture toughness characterization of austempered ductile iron produced using both conventional and two-step austempering processes. Mater. Des., 2009, 30(6): 1866.

[17] Teng T.L., Chu Y.A., Chang F.A., Chin H.S., Lee M.C. The dynamic analysis of nuclear waste cask under impact loading. Ann. Nucl. Energy, 2003, 30(14): 1473.

[18] Jakšić N., Nilsson K. Finite element modelling of the one meter drop test on a steel bar for the CASTOR cask. Nucl. Eng. Des., 2009, 239(2): 201.

[19] Brynda J., Hosnedl P., Jilek M., Picek M. Material issues in manufacturing and operation of transport and storage spent fuel casks. [in] Transactions of 15th International Conference on Structural Mechanics in Reactor Technology, Seoul, 1999 247.

[20] Kazemi M., Kiani-Rashid A.R., Nourian A., Babakhani A. Investigation of microstructural and mechanical properties of austempered steel bar-reinforced ductile cast iron composite. Mater. Des., 2014, 53, 1047.

[21] Delprete C., Sesana R. Experimental characterization of a Si–Mo–Cr ductile cast iron. Mater. Des., 2014, 57, 528.

[22] Alhussein A., Risbet M., Bastien A., Chobaut J.P., Balloy D., Favergeon J. Influence of silicon and addition elements on the mechanical behavior of ferritic ductile cast iron. Mater. Sci. Eng. A, 2014, 605, 222.

[23] Hsu C.H., Lin K.T. A study on microstructure and toughness of copper alloyed and austempered ductile irons. Mater. Sci. Eng. A, 2011, 528(18): 5706.

[24] Cullity B.D. Elements of X-ray Diffraction. Massachusetts, Addison-Wesley Publishing Company, 1956

[25] Sorenson K.B., Salzbrenner R.J. Quality assurance aspects in using ductile cast iron for transportation casks. [in] Waste Management’ 88, Phoenix, 1988 107.

[26] Sohi M. H., Ahmadabadi M. N., Vahdat A. B. The role of austempering parameters on the structure and mechanical properties of heavy section ADI. J. Mater. Process. Technol., 2004, 153-154, 203.

[27] Xu W., Ferry M., Wang Y. The effect of ausferrite formation on the mechanical properties of gray iron. Scripta Mater., 2004, 51(7): 705.

[28] Eric O., Sidjanin L., Miskovic Z., Zec S., Jovanovic M.T. Microstructure and toughness of CuNiMo austempered ductile iron. Mater. Lett., 2004, 58(22-23): 2707.

[29] Han J.M., Zou Q., Barber G.C., Nasir T., Northwood D.O., Sun X.C., Seaton P. Study of the effects of austempering temperature and time on scuffing behavior of austempered Ni–Mo–Cu ductile iron. Wear, 2012, 290-291, 99.

[30] Rebasa N., Dommarco R., Sikora J. Wear resistance of high nodule count ductile iron. Wear, 2002, 253(7-8): 855.

[31] Sun Y.F., Hu S.M., Xiao Z.Y., You S.S., Zhao J.Y., Lv Y.Z. Effects of nickel on low-temperature impact toughness and corrosion resistance of high-ductility ductile iron. Mater. Des., 2012, 41, 37.

[32] El-Banna E.M. A study of ferritic centrifugally cast ductile cast iron. Mater. Lett., 1994, 20(3-4): 99.

[33] Cho G.S., Choe K.H., Lee K.W., Ikenaga A. Effects of alloying elements on the microstructures and mechanical properties of heavy section ductile cast Iron. J. Mater. Sci. Technol., 2007, 23(1): 97.

[34] Gonzaga R.A. Influence of ferrite and pearlite content on mechanical properties of ductile cast irons. Mater. Sci. Eng. A, 2013, 567, 1.

[35] Shelton P.W., Bonner A.A. The effect of copper additions to the mechanical properties of austempered ductile iron (ADI). J. Mater. Process. Technol., 2006, 173(3): 269.

[36] Lin B.Y., Chen E.T., Lei T.S. The effect of alloy elements on the microstructure and properties of austempered ductile irons. Scripta Metall. Mater., 1995, 32(9): 1363.

[37] Kerlins V. Modes of Fracture. ASM Handbook, Kathleen Mills, Joseph R. Davis, James D. Destefani, Deborah A. Dieterich, Heather J. Frissell, George M. Crankovic, and Diane M. Jenkins, eds., ASM International, USA, 1987 12.

[38] Sen S., Mishra S.C., Sarkar S. Characterization of ADI through fractographic analysis. Technol. World, V, 2010, 1, 45.