Preparation and tensile properties of DD5 single crystal castings

Abstract

The preparation procedure of DD5 single crystal castings was optimized. The microstructure characteristics of DD5 single crystal superalloy were investigated by microstructure observation and segregation behavior examination. The results show that the grain orientation is optimized by constraining the spiral crystallizer in [001] orientation and spatial scale. Also, the γ’ phase of inter-dendrites is larger and more irregular than that in dendrite arms. High temperature tensile tests of DD5 single crystal castings exhibit that the peak stress increases with increasing temperature, while the area reduction shows an opposite trend, when the temperature is below 800°C; meanwhile, when the temperature is between 800°C and 1000°C, the fracture stress of the alloy is the same as the peak stress. The fracture mode changes from shear to ductile with increasing temperature from 600°C and 1000°C.

Keywords

superalloys / single crystals / segregation / tensile properties / alloy preparation / castings

References

[1] Wang F., Ma D., Zhang J., Bogner S., Bührig-Polaczek A. Solidification behavior of a Ni-based single crystal CMSX-4 superalloy solidified by downward directional solidification process. Mater. Charact., 2015, 101, 20.

[2] Wu B.P., Li L.H., Wu J.T., Wang Z., Wang Y.B., Chen X.F., Dong J.X., Li J.T. Microstructure and stress rupture properties of polycrystal and directionally solidified castings of nickel-based superalloys. Int. J. Miner. Metall. Mater., 2014, 21(1): 58.

[3] Liu D.S., Zhang D.X., Liang J.W., Wen Z.X., Yue Z.F. Prediction of creep rupture life of a V-notched bar in DD6 Ni-based single crystal superalloy. Mater. Sci. Eng. A, 2014, 615, 14.

[4] Wang L., Yao Y.J., Liu B., Zhong B.Y., Dong J.X. Effect of cooling rate on the phase transformation and stability of the mushy zone during the solidification of Waspaloy. Int. J. Miner. Metall. Mater., 2010, 17(4): 464.

[5] Martins P.M., Rocha F. Characterization of crystal growth using a spiral nucleation model. Surf. Sci., 2007, 601(16): 3400.

[6] Huang M., Zhuo L.C., Liu Z.L., Lu X.G., Shi Z.X., Li J.R., Zhu J. Misorientation related microstructure at the grain boundary in a nickel-based single crystal superalloy. Mater. Sci. Eng. A, 2015, 640, 394.

[7] Shi Z.X., Li J.R., Liu S.Z. Effects of Ru on the microstructure and phase stability of a single crystal superalloy. Int. J. Miner. Metall. Mater., 2012, 19(11): 1004.

[8] Koster M., Le K.C. Formation of grains and dislocation structure of geometrically necessary boundaries. Mater. Sci. Eng. A, 2015, 643, 12.

[9] Carter J.L.W., Kuper M.W., Uchic M.D., Mills M.J. Characterization of localized deformation near grain boundaries of superalloy René-104 at elevated temperature. Mater. Sci. Eng. A, 2014, 605, 127.

[10] Shade P.A., Uchic M.D., Dimiduk D.M., Viswanathan G.B., Wheeler R., Fraser H.L. Size-affected single-slip behavior of René N5 microcrystals. Mater. Sci. Eng. A, 2012, 535, 53.

[11] Wang F., Ma D.X., Zhang J., Liu L., Bogner S., Bührig-Polaczek A. Effect of local cooling rates on the microstructures of single crystal CMSX-6 superalloy: A comparative assessment of the Bridgman and the downward directional solidification processes. J. Alloys Compd., 2014, 616, 102.

[12] Jahangiri M.R., Arabi H., Boutorabi S.M.A. Investigation on the dissolution of η phase in a cast Ni-based superalloy. Int. J. Miner. Metall. Mater., 2013, 20(1): 42.

[13] Guo W., Gao T.F., Cui X.F., Zhu Y., Chu P.K. Interfacial reactions and zigzag groove strengthening of C/C composite and Rene N5 single crystal brazed joint. Ceram. Int., 2015, 41(9): 11605.

[14] Wang F., Ma D., Zhang J., Liu L., Hong J., Bogner S., Bührig-Polaczek A. Effect of solidification parameters on the microstructures of superalloy CMSX-6 formed during the downward directional solidification process. J. Cryst. Growth, 2014, 389, 47.

[15] Xiong X.H., Quan D.M., Dai P.D., Wang Z.P., Zhang Q.X., Yue Z.F. Tensile behavior of nickel-base single-crystal superalloy DD6. Mater. Sci. Eng. A, 2015, 636, 608.

[16] Zhuo L.C., Liang S.H., Wang F., Xu T., Wang Y.L., Yuan Z.X., Xiong J.C., Li J.R., Zhu J. Kinetics and microstructural evolution during recrystallization of a single crystal superalloy. Mater. Charact., 2015, 108, 16.

[17] Meng J., Jin T., Sun X.F., Hu Z.Q. Surface recrystallization of a single crystal nickel-base superalloy. Int. J. Miner. Metall. Mater., 2011, 18(2): 197.

[18] Tian S.G., Wu J., Shu D.L., Su Y., Yu H.C., Qian B.J. Influence of element Re on deformation mechanism within γ' phase of single crystal nickel-based superalloys during creep at elevated temperatures. Mater. Sci. Eng. A, 2014, 616, 260.

[19] Wang J.L., Chen M.H., Zhu S.L., Wang F.H. Ta effect on oxidation of a nickel-based single-crystal superalloy and its sputtered nanocrystalline coating at 900–1100°C. Appl. Surf. Sci., 2015, 345, 194.

[20] Zhao X.B., Liu L., Zhang W.G., Liu G., Zhang J., Fu H.Z. Segregation behavior of alloying elements in different oriented single crystal nickel based superalloys. Mater. Lett., 2009, 63(30): 2635.