Effect of Ti Addition on the Microstructure and Properties of a High Speed Steel Roll

Abstract

In the present work, the effect of Ti addition on microstructure and properties of high speed steel (HSS) used for rolls was investigated utilizing optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy spectrum analysis. The results indicated that as-cast microstructure of the HSS roll is mainly composed of MC, M2C and M7C3 eutectic carbides and metallic matrix consishing of a mixture of martensite, austenite, and pearlite. The carbides are connected or placed next to each other to form a network along grain boundaries. The addition of 0.5 wt.-% Ti leads to a great change in the morphology, size and distribution of carbides. The carbide network tends to break, and all carbides are refined and distributed homogeneously in the matrix. After normalizing treatment at 1050 °C, the carbides in the Ti containing HSS roll transform into granular or nodular distribution. The mechanical properties, thermal fatigue, and wear resistance of Ti containing HSS roll are more excellent than that of the HSS roll without titanium.