The Effect of Magnesium on the Microstructure and Stress Rupture Properties of Hastelloy X Supealloy

Subject Areas : Casting

Masumeh seifollahi ¹ , Afagh panahi moghaddam ² , seysd Mahdi Abbasi ³ , seyed Mahdi ghazi mir saeed ⁴

1 - Malek Ashter University of Technology, Metallic Materials Research Center (MMRC_MA), Tehran, Iran.
2 - Malek Ashter University of Technology, Metallic Materials Research Center (MMRC_MA), Tehran, Iran.
3 - Malek Ashter University of Technology, Metallic Materials Research Center (MMRC_MA), Tehran, Iran.
4 - Malek Ashter University of Technology, Metallic Materials Research Center (MMRC_MA), Tehran, Iran.

Received: 2019-04-23 Accepted : 2019-07-04 Published : 2019-08-01

Keywords: Microstructure, Magnesium, Hastelloy X Superalloy, Stress Rupture Life,

Abstract :

In the present study, the effects of magnesium on the microstructural characteristics and stress-rupture properties of the Hastelloy X superalloy were investigated. In this regard, four alloys with different amounts of magnesium (0, 17, 33, 47 ppm) were cast via the vacuum induction melting and then purified via the electro slag remelting. Microstructural observations were carried out through optical and scanning electron microscopes, and phase analysis was performed by X-ray diffraction. The stress rupture test was carried out at 815 °C/130 MPa. The results showed an almost significant effect of magnesium on decreasing grain size and sulfur content and increasing M6C carbides volume fraction. Magnesium changed the morphology of carbides from the course and continue to finely divide one. Mg segregated at the grain and carbide boundary decreases the lattice parameters of the matrix and changes the composition of M6C. Magnesium increased the rupture life by 46%. The most important causes for improving the rupture life of the Hastelloy X in the presence of magnesium are the increasing carbides volume fraction, improving its morphology, and decreasing sulfur content.

References:

[1] L. M. Pike, "100+ years of wrought alloy development at haynes international", in 8th International Symposiumon Superalloy 718 and Derivatives, TMS, 2014, 15-30.

[2] Y. ming, N. yujing, "study on nonequilibrium grain-boundary segregation of sulfur among Hastelloy X", Adv. Mat. Rese., Vol. 181-182, 2011, pp. 861-865.

[3] H. Tsuji, T. Shimizu, S. Isobe, H. Nakajima, "Effect of minor alloying elements on hotworkability of Ni-Cr-W superalloys", j. Nucl. Sci. Tech., Vol. 31, 1994, 32-39. 

[4] S.Yamaguchi, H. Kobayashi, T. Matsumiya, S. Hayami, "Effect of Minor Elements on Hot Workability of Nickel-Base Superalloys", Met. Tech., Vol. 6, 1979, pp. 170-175.

[5] H. Bor, C. Chao, C. Ma, "The Influence of Magnesium on Carbide Characteristics and Creep Behavior of The Mar-M247 Superalloy", Scripta Mater., Vol. 38, 1997, pp. 329-335.

[6] K. Banerjee, "The Role of Magnesium in Superalloys—A Review", Mat. Sci. Appl., Vol. 2, 2011, pp. 1243-1248.

[7] Z. X. xie, G. Chen, "The Role of Mg on Structure and Mechanics Properties in Alloy 718" , Metall. Society, 1988, pp. 635-642. [8] Y. Azakli, M.  Tarakci M., "Towards understanding the effects of magnesium addition on microstructural and thermal properties of NiAlCr alloys in as-cast and heat treated states", j. alloys comp., Vol. 699, 2017, pp.151-159. [9] H. Bor, C. Chao, C. and Ma, "The Effects of Mg Microaddition on the Mechanical Behavior and Fracture Mechanism of Mar-M247 Superalloy at Elevated Temperatures", Metall. Mat. Trans. A, Vol. 30, 1999, pp. 551-561.

[8] X. L. M. Lv, Y. Min, C. Liu, M. Jiang, B. Wang, X. Wang, "Effect of Trace Magnesium Addition on the Characteristics of Mechanical Properties in High Strength Low Alloy Steel", Advances In Engineering Research, 2015, pp.1-8.

[9] K. Kimura, S. Fukumoto, G. I. Shigesato, A. Takahashi, "Effect of Mg Addition on Equiaxed Grain Formation In Ferritic Stainless Steel", Isij Int., Vol. 53, 2013, pp. 2167-2175.

[10] H. Tawancy, "Long-Term             Ageing Characteristics of Hastelloy Alloy X", J. Mat. Sci., Vol. 18, 1983, pp. 2976-2986.

[11] M. Aghaie-khafri, N. Golarzi, "Dynamic and Metadynamic Recrystallization of Hastelloy X Superalloy", J. Mat. Sci., Vol. 43, 2008, pp. 3717-3724.

[12] S.S. Batsanov, "Van der waals radii of elements", Inorganic Mat., 2001, vol. 37, pp.871–885.

[13] G. chen, D. wang, Z.  Xu, J. Fu, K. Ni, X. Xie, "The role of small amounts of Magnesium in Nickle-base and Iron-Nickle-base superalloys after high temperature long time exposures", in superalloys , TMS, 1984, pp.611-620. [16] J. X. Dong, X. S.  Xie, R. Thompson, "The influence of sulfur on stress-rupture fracture in inconel 718 superalloys", Metall. Mate. Trans. A, Vol. 31, 2000, pp 2135–2144.

[14] S. Jonas, M. Lundberg, H. Brodin, J.  Moverare, "Dwell-fatigue crack propagation in additive manufactured Hastelloy X", Mat. Sci. Eng. A, Vol. 722, 2018, pp. 30-36.

[15] M. Kirka, R. Dehoff,  "Mechanical Properties of Hastelloy X Fabricated by Electron Beam Melting", in Materials Science & Technology conf., Salt Lake City, UT, October 23-27, 2016.