Script MC carbides are easily formed in the welding of Ni-base superalloys. In this study, the effect of script MC carbides on the tensile behavior of laser-welded DZ125L/IN718 joints in the fusion zone was investigated. The phase size, phase distribution and element distribution of script MC carbides, and the orientation relationship between script MC carbides and γ matrix were carefully analyzed using SEM, EDS, TEM and HRTEM. The breaking behavior of script MC carbides was investigated through interrupted tensile testing at 650 °C. The results demonstrate that the script MC carbides are distributed in the interdendrites with an average size of 3.5 \(\pm\) 1.6 μm. They are (Ta, Nb, W, Ti and Mo)C and incoherent with the γ matrix. The fine script MC carbides are beneficial for improving both the strength and ductility of the fusion zone by improving coordinated deformation with γ matrix. However, the script MC carbides are found broken very early. About 9% script MC carbides have been broken after welding. The number of broken carbides increases with the increasing plastic strain. The majority of the cracks are found at the necks of the script MC carbides. The breaking mechanism of script MC carbides reveals that the high breaking tendency of the neck is attributed to the relatively long arm length and, more importantly, to the minimum section width size. Modifying the carbide morphology into a sphere is suggested for lowering the breaking tendency of MC carbides.
This is a preview of subscription content, log in to check access.
Buy single article
Instant access to the full article PDF.
Price includes VAT for USA
Subscribe to journal
Immediate online access to all issues from 2019. Subscription will auto renew annually.
This is the net price. Taxes to be calculated in checkout.
Long H, Mao S, Liu Y, Zhang Z, Han X (2018) Microstructural and compositional design of Ni-based single crystalline superalloys—a review. J Alloys Compd 743:203–220. https://doi.org/10.1016/j.jallcom.2018.01.224
Kotval PS, Venables JD, Calder RW (1972) The role of hafnium in modifying the microstructure of cast nickel-base superalloys. Metall Mater Trans B 3(2):457–462. https://doi.org/10.1007/BF02642049
Starink MJ, Cama H, Thomson RC (1997) MC carbides in the Hf containing Ni based superalloy MarM002. Scr Mater 38(1):73–80. https://doi.org/10.1016/S1359-6462(97)00409-0
Chen J, Lee JH, Jo CY, Choe SJ, Lee YT (1998) MC carbide formation in directionally solidified MAR-M247 LC superalloy. Mater Sci Eng A 247(1):113–125. https://doi.org/10.1016/S0921-5093(97)00761-2
Sun WR, Lee JH, Seo SM, Choe SJ, Hu ZQ (1999) The eutectic characteristic of MC-type carbide precipitation in a DS nickel-base superalloy. Mater Sci Eng A 271(1–2):143–149. https://doi.org/10.1016/S0921-5093(99)00189-6
Chen QZ, Jones CN, Knowles DM (2002) Effect of alloying chemistry on MC carbide morphology in modified RR2072 and RR2086 SX superalloys. Scr Mater 47(10):669–675. https://doi.org/10.1016/S1359-6462(02)00266-X
Chen QZ, Jones N, Knowles DM (2002) The microstructures of base/modified RR2072 SX superalloys and their effects on creep properties at elevated temperatures. Acta Mater 50(5):1095–1112. https://doi.org/10.1016/S1359-6454(01)00410-4
Wang F, Xu W, Ma D, Bührig-Polaczek A (2019) Co-growing mechanism of γ/γ′ eutectic on MC-type carbide in Ni-based single crystal superalloys. J Alloys Compd 792:505–509. https://doi.org/10.1016/j.jallcom.2019.04.067
Yang J, Zheng Q, Sun X, Guan H, Hu Z (2006) Morphological evolution of MC carbide in K465 superalloy. J Mater Sci 41(19):6476–6478. https://doi.org/10.1007/s10853-006-0684-5
Yang J, Zheng Q, Sun X, Guan H, Hu Z (2006) Relative stability of carbides and their effects on the properties of K465 superalloy. Mater Sci Eng A 429(1–2):341–347. https://doi.org/10.1016/j.msea.2006.05.091
Liu LR, Jin T, Zhao NR, Wang ZH, Sun XF, Guan HR, Hu ZQ (2004) Effect of carbon addition on the creep properties in a Ni-based single crystal superalloy. Mater Sci Eng A 385(1–2):105–112. https://doi.org/10.1016/j.msea.2004.06.003
He LZ, Zheng Q, Sun XF, Guan HR, Hu ZQ, Tieu AK, Lu C, Zhu HT (2005) Effect of carbides on the creep properties of a Ni-base superalloy M963. Mater Sci Eng A 397(1–2):297–304. https://doi.org/10.1016/j.msea.2005.02.038
Liang T, Wang L, Liu Y, Song X (2018) Effects of strain rate on tensile deformation and fracture behavior of directionally solidified superalloy DZ125L. J Mater Eng Perform 27(2):721–727. https://doi.org/10.1007/s11665-017-3084-x
Kurz W, Fisher DJ (1998) Fundamentals of solidification, 4th edn. Trans Tech Pub, Switzerland
Zhang W, Liu L (2012) Solidification microstructure of directionally solidified superalloy under high temperature gradient. Rare Met 31(6):541–546. https://doi.org/10.1007/s12598-012-0554-z
Li XW, Wang L, Dong JS, Lou LH (2014) Effect of solidification condition and carbon content on the morphology of MC carbide in directionally solidified nickel-base superalloys. J Mater Sci Technol 30(12):1296–1300. https://doi.org/10.1016/j.jmst.2014.06.010
David SA, Vitek JM, Babu SS, Boatner LA, Reed RW (1997) Welding of nickel base superalloy single crystals. Sci Technol Weld Joi 2(2):79–88. https://doi.org/10.1179/stw.19184.108.40.206
Pang M, Yu G, Wang HH, Zheng CY (2008) Microstructure study of laser welding cast nickel-based superalloy K418. J Mater Process Tech 207(1–3):271–275. https://doi.org/10.1016/j.jmatprotec.2007.12.091
Liang T, Wang L, Liu Y, Song X (2018) Microstructure and mechanical properties of laser welded joints of DZ125L and IN718 nickel base superalloys. Met Mater Int 24(3):604–615. https://doi.org/10.1007/s12540-018-0073-z
Osoba LO, Ding RG, Ojo OA (2012) Microstructural analysis of laser weld fusion zone in Haynes 282 superalloy. Mater Charact 65:93–99. https://doi.org/10.1016/j.matchar.2011.12.009
Yang F, Liu E, Zhi Z, Tong J, Ning L (2014) Influence of Ti content on microstructure, mechanical properties and castability of directionally solidified superalloy DZ125L. Mater Des 61:41–49. https://doi.org/10.1016/j.matdes.2014.04.059
Reed RC (2006) The superalloys: fundamentals and applications. Cambridge University Press, Cambridge
Zheng L, Zhang G, Lee TL, Gorley MJ, Wang Y, Xiao C, Li Z (2014) The effects of Ta on the stress rupture properties and microstructural stability of a novel Ni-base superalloy for land-based high temperature applications. Mater Des 61:61–69. https://doi.org/10.1016/j.matdes.2014.04.055
Hollox GE (1968) Microstructure and mechanical behavior of carbides. Mater Sci Eng 3(3):121–137. https://doi.org/10.1016/0025-5416(68)90001-3
Chen JH, Cao R (2015) Chapter 1—introduction. In: Chen JH, Cao R (eds) Micromechanism of cleavage fracture of metals. Butterworth-Heinemann, Boston, pp 1–54. https://doi.org/10.1016/B978-0-12-800765-5.00001-0
Yu Y (2013) Principles of metallography, 2nd edn. Metallurgical Industry Press, Beijing
Juvinall RC, Marshek KM (2006) Fundamentals of machine component design, 4th edn. Wiley, Hoboken
Zhou P, Yu J, Sun X, Guan H, Hu Z (2012) Roles of Zr and Y in cast microstructure of M951 nickel-based superalloy. T Nonferr Metal Soc 22(7):1594–1598. https://doi.org/10.1016/S1003-6326(11)61361-7
Huang HE, Koo CH (2004) Effect of zirconium on microstructure and mechanical properties of cast fine-grain CM 247 LC superalloy. Mater Trans 45(2):554–561. https://doi.org/10.2320/matertrans.45.554
Bor HY, Chao CG, Ma CY (1999) The effects of Mg microaddition on the mechanical behavior and fracture mechanism of MAR-M247 superalloy at elevated temperatures. Metall Mater Trans A 30(3):551–561. https://doi.org/10.1007/s11661-999-0047-3
Bor HY, Ma CY, Chao CG (2000) The influence of Mg on creep properties and fracture behaviors of Mar-M247 superalloy under 1255 K/200 MPa. Metall Mater Trans A 31(5):1365–1373. https://doi.org/10.1007/s11661-000-0255-3
Zhang HW, Wu YS, Qin XZ, Zhou LZ, Li XW (2018) Microstructures and high-temperature mechanical properties of a directionally solidified Ni-based superalloy: Influence of boron content. J Alloys Compd 767:915–923. https://doi.org/10.1016/j.jallcom.2018.07.162
This study was financial supported by the National Natural Science Foundation of China (Grant Nos. U1708253 and 51571052), and the Science and Technology Major Project (Grant No. 2017-VI-0002).
Conflict of interest
The authors declare that they have no conflict of interest.
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Liang, T., Wang, L., Liu, Y. et al. Role of script MC carbides on the tensile behavior of laser-welded fusion zone in DZ125L/IN718 joints at 650 °C. J Mater Sci 55, 13389–13397 (2020). https://doi.org/10.1007/s10853-020-04931-w