The experimental steel is smelted in the 25kg vacuum induction melting furnace (Fig. 1) of the Institute of engineering and technology of Beijing University of science and technology. Firstly, the pure iron is melted and the steel is tapped at 1500-1550 ° C. before tapping, the alloy is added to the vacuum induction furnace for alloying. At the same time, desulfurization, deoxidation, detection and adjustment of chemical element content are carried out. Nb and Modification of Ti and Y; When the temperature drops to 1450-1470 ° C in the vacuum induction furnace, pour it into the cavity of the metal mold; After casting, it shall be cooled naturally for 1.5-2h. After cooling, it shall be unpacked and the castings shall be cleaned. The physical drawing of metal mold and ingot is shown in Figure 2.
In the, the microstructure compactness and uniformity of ingot surface and riser are very different from the matrix, so the above areas are avoided in all subsequent experiments. The metallographic structure of the ingot is shown in Figure 3. Obvious coarse dendrites can be seen in the figure. The dendrites are mainly composed of martensite. This is because the metal mold placed at room temperature provides a fast cooling speed. At this time, the experimental steel needs subsequent heat treatment to obtain the expected microstructure and properties.
(1) The composition (wt.%) of bainitic Martian multiphase wear-resistant cast steel is designed: 0.37-0.40c, 1.1-1.6si, 2.0-2.5mn, 0.003-0.006b, 1.2-1.5cr, 0.3-0.5mo, 0.04-0.06nb, 0.01-0.03ti ０．０１-０．０３Ｙ。
(2) Combined with the typical failure forms and working conditions of crusher liner, it is expected that the microstructure of bainite + martensite + a small amount of retained austenite can be obtained in the experimental steel.
(3) The laboratory smelting and casting process of Bei Ma multiphase wear-resistant cast steel is designed: melting of pure iron – adding alloy elements – adding modifier – tapping at 1500-1550 ° C – casting at 1450-1470 ° C – natural cooling.