Solidification behaviors and casting microstructures of 2.25Cr-1Mo-0.25V steel
1.School of Mechanical Engineering, Shanghai Dianji University, Shanghai 200245, China; 2.School of Materials Science and Enginee-ring, North University of China, Taiyuan, Shanxi 030051, China; 3.Shanghai Heavy Machinery Ltd. Co., Shanghai 200245, China
Abstract：To investigate the microstructural evolution of 2.25Cr-1Mo-0.25V steel during the preparation in the new generation hydro-desulfurization reactor, the solidification behaviors and the as-cast microstructures of steel were discussed by laser scanning confocal microscope, scanning electronic microscope, transmission electronic microscope and X-ray diffractometer. The results show that during the cooling process from liquid, the δ-ferrite precipitates from liquid phase, and then the δ-ferrite and the retained liquid phase transform into austenite by peritectic reaction. The retained δ-ferrite undergoes allotropic transformtion into austenite accompanied with black crack. The granular bainite microstructures of the as-cast specimen are composed of bainitic ferrite matrix and M-A islands, and contain a small amount of fine carbides with ε-carbide, M7C3, M3C and MC. The segregation of alloying elements is appeared in casting microstructures, while it is not related to the regions of bainitic ferrite and M-A islands.
2013, Vol. 34 
