Abstract
Transformation and coarsening of carbides in 2.25Cr-1Mo steel weld metal during tempering at 700 °C for different time intervals ranging from 1 to 150 h were examined by transmission electron microscopy and scanning electron microscopy. M3C carbides were observed in the as-welded specimens and when tempered, the precipitates were mainly composed of M3C, M7C3, and M23C6 carbides. A sequence for corresponding carbide transformation during tempering with initial precipitation of M3C and the subsequent precipitation of M7C3 and M23C6 was proposed. The precipitation of M7C3 with higher chromium content was the main factor contributing to the decrease in coarsening rate of precipitates after prolonged tempering. The decrease in hardness of the tempered specimens agreed well with the prediction of the weakening of precipitation strengthening owing to the coarsening of carbides.
Similar content being viewed by others
References
Bhadeshia H K D H. Bainite in Steels [M]. London: The Institute of Materials, 2001.
Klueh R L, Swindeman R W. The Microstructure and Mechanical Properties of a Modified 2.25Cr-1Mo Steel [J]. Metall Trans, 1986, 17A(6): 1027.
Cheruvu N S. Degradation of Mechanical Properties of Cr-Mo-V and 2.25Cr-1Mo Steel Components After Long-Term Service at Elevated Temperatures [J]. Metall Trans, 1989, 20A(1): 87.
Thomson R C, Bhadeshia H K D H. Changes in Chemical Composition of Carbides in 2.25Cr-1Mo Power Plant Steel: Part 1 Bainitic Microstructure [J]. Mater Sci Technol, 1994, 10(3): 193.
Baker R G, Nutting J. Tempering of 2.25Cr-1Mo Steel After Quenching and Normalization [J]. Journal of the Iron and Steel Institute, 1959, 192(7): 257.
Tsai M C, Yang J R. Microstructural Degeneration of Simulated Heat-Affected Zone in 2.25Cr-1Mo Steel During High-Temperature Exposure [J]. Mater Sci Eng, 2003, 340A(1): 15.
Tsai M C, Chiou C S, Yang J R. Microstructural Evolution of Simulated Heat-Affected Zone in Modified 2.25Cr-1Mo Steel During High Temperature Exposure [J]. J Mater Sci, 2003, 38(11): 2373.
Janovec J, Svoboda M, Kroupa A, et al. Thermal-Induced Evolution of Secondary Phases in Cr-Mo-V Low Alloy Steels [J]. J Mater Sci, 2006, 41(1): 3425.
Janovec J, Svoboda M, Vyrostkova A, et al. Time-Temperature-Precipitation Diagrams of Carbide Evolution in Low Alloy Steels [J]. Mater Sci Eng, 2006, 402A(1/2): 288.
Lifshitz I M, Slyozov V V. The Kinetic of Precipitation From Supersaturated Solid Solutions [J]. J Phys Chem Solids, 1961, 19(1/2): 35.
YONG Qi-long. Second Phase in Steels [M]. Beijing: Metallurgical Industry Press, 2006 (in Chinese).
Lee H L, Allen S M, Grujicic M. Coarsening Resistance of M2C Carbides in Secondary Hardening Steels: Part I. Theoretical Model for Multicomponent Coarsening Kinetics [J]. Metall Trans, 1991, 22(12): 2863.
Miyamoto G, Oh J C, Hono K, et al. Effect of Partitioning of Mn and Si on the Growth Kinetics of Cementite in Tempered Fe-0.6 Mass % C Martensite [J]. Acta Mater, 2007, 55 (15): 5027.
Abe F. Coarsening Behavior of Lath and Its Effect on Creep Rates in Tempered Martensitic 9Cr-W Steels [J]. Mater Sci Eng, 2004, 387–389: 565.
Beatty J H, Shiflet G J. Orowan Strengthening by Mo2C Fibers and Needle Interphase Precipitates in Fe-C-Mo Dual-Phase Steels [J]. Metall Trans, 1988, 19A(6): 1617.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Tao, P., Zhang, C., Yang, Zg. et al. Evolution and coarsening of carbides in 2.25Cr-lMo steel weld metal during high temperature tempering. J. Iron Steel Res. Int. 17, 74–78 (2010). https://doi.org/10.1016/S1006-706X(10)60103-3
Received:
Published:
Issue Date:
DOI: https://doi.org/10.1016/S1006-706X(10)60103-3