Influence of Deep Cryogenic Treatment on Microstructures and Mechanical Properties of an Ultrafine-Grained WC-12Co Cemented Carbide

doi:10.1007/s40195-014-0134-3

Abstract

Abstract:

Effect of deep cryogenic treatment (DCT) on the microstructures and mechanical behavior of ultrafine-grained WC-12Co cemented carbide was investigated by using XRD, SEM, and DSC. The phase transformations of pure Co and binder phase Co in cemented carbide were analyzed in detail to correlate the strengthening mechanism with its α → ε phase transition. The results show that DCT resulted in a slight increase in hardness and bending strength of ultrafine-grained WC-12Co cemented carbide. For the ultrafine-grained cemented carbide after DCT, there is no significant change in the microstructure and the elemental distribution of the cemented carbides, but the fractured morphology shows a feature of plastic deformation. In the cases of pure Co and the binder phase Co in WC-12Co cemented carbide, they exhibit different features of phase transformation. The improvement of mechanical property of cemented carbide can be attributed to the increased amount of ε-Co in WC-12Co composites after DCT.

Key words: WC-12Co composite, Cemented carbide, Deep cryogenic treatment, Mechanical properties, Microstructure

Zhang Hejia, Chen Liqing, Sun Jing, Wang Wenguang, Wang Quanzhao. Influence of Deep Cryogenic Treatment on Microstructures and Mechanical Properties of an Ultrafine-Grained WC-12Co Cemented Carbide[J]. Acta Metallurgica Sinica (English Letters), 2014, 27(5): 894-900.

Figures/Tables 9

Fig.1 The hardness change of the ultrafine-grained WC-12Co cemented carbide with time for deep cryogenic treatment

Fig.2 Relationship between bending strength and deep cryogenic treatment time for ultrafine-grained WC-12Co cemented carbides

Fig.3 SEM micrographs showing the fracture surfaces of WC-12Co cemented carbide: a as-sintered; b deep cryogenically treated in liquid nitrogen for 72 h

Fig.4 SEM micrograph and elemental distributions of cemented carbides before deep cryogenic treatment: a microstructure; b Co distribution; c C distribution; d W distribution

Fig.5 SEM micrograph and elemental distribution of cemented carbides after deep cryogenic treatment for 72 h: a microstructure; b Co distribution; c C distribution; d W distribution

Fig.6 Phase transition curve of Co in cooling process

Fig.7 Heat flow curves of cemented carbide and pure Co during cooling

Fig.8 Heat flow curve of cemented carbide in reheating process

Fig.9 XRD spectra of WC-12Co cemented carbides before and after cryogenic treatment for 72 h

References 19

[1]	R. Bao, J.H. Yi, Y.D. Peng, H.Z. Zhang, A.K. Li, Trans. Nonferrous Met. Soc. China 22, 853 (2012)
[2]	R. Bao, J.H. Yi, Y.D. Peng, H.Z. Zhang, Trans. Nonferrous Met. Soc. China 23, 372 (2013)
[3]	S.X. Zhao, X.Y. Song, J.X. Zhang, X.M. Liu,Acta Metall. Sin. 43, 107(2007). (in Chinese)
[4]	A.Y.L. Yong, K.H.W. Seah, M. Rahman, Int. J. Adv. Manuf. Technol. 32, 638(2007)
[5]	J. Gisip, R. Gazo, H.A. Stewart, J. Mater. Process. Technol. 209, 5117(2009)
[6]	A.Y.L. Yong, K.H.W. Seah, M. Rahman, Int. J. Mach. Tools Manuf 46, 2051 (2006)
[7]	S.S. Gill, R. Singh, H. Singh, J. Singh,Int. J. Mach. Tools Manuf. 49, 256(2009)
[8]	D.N. Collins,Heat Treat. Met. 23(2), 40(1995)
[9]	N.S. Kalsia, R. Sehgalb, V.S. Sharma,Mater. Manuf. Process. 25, 1077(2010)
[10]	H.A. Stewart,Forest Prod. J. 54, 53(2004)
[11]	S.S. Gill, H. Singh, R. Singh, J. Singh,Int. J. Adv. Manuf. Technol. 48, 175(2010)
[12]	T.V.S. Reddy, T. Sornakumar, M.V. Reddy, R. Venkatram, A. Senthilkumar, Mach. Sci. Technol. 13, 269(2009)
[13]	J.S. Liu, Y.X. Pu, M.F. Tan,Hot Working Technol. 41(6), 184(2012). (in Chinese)
[14]	D. Thakur, B. Ramamoorthy, L. Vijayaraghavan,Mater. Lett. 62, 4403(2008)
[15]	Y. Jiang, D. Chen, Mater. Sci. Eng. A 528, 1735 (2011)
[16]	Z.H. Chen, L. Fan, Y. Jiang, L.M. Wang, W. Peng, X.H. Zhou, Cem. Carbide 27(01), 1 (2010).(in Chinese)
[17]	J.W. Wei, L.L. Tang, S.H. Li, X.C. Wu, Trans. Nonferrous Met. Soc. China 22, 2421 (2012)
[18]	T.V.S. Reddy, T. Sornakumar, M.V. Reddy, R. Venkatram, Int. J. Refract. Met. Hard Mater. 27(1), 46(2009)
[19]	T.V.S. Reddy, T. Sornakumar, M.V. Reddy, R. Venkatram, Cryogenics 48(9-10), 458 (2008)