Effect of titanium and rare earth microalloying on microsegregation, eutectic carbides of M2 high speed steel during ESR process

The effects of RE and Ti microalloying during electroslag remelting (ESR) process on the micro -segregation and morphology of eutectic M2C carbides in M2 high speed steel were investigated. The results show that the addition of 0.2 wt% RE can alleviate the segregation of C, W, Mo, V and Cr, while the morphology of eutectic M2C carbides hardly changes. The microalloying with the addition of 0.5 wt% Ti has the lowest degree of microsegregation due to the improvement of primary dendrites by the effective heterogeneous nucleating agent of (Ti,V) (C,N) particles. The addition of Ti makes the morphology of M2C carbides change from rod-like or maze-like shape into a coarse feathery shape, exhibiting anisotropic facet growth characteristics. For the microalloying of 0.2 wt% RE and 0.5 wt% Ti, the segregation of the main metal alloying elements is slightly more severe than that of the addition of only RE or Ti. Under the combined action of RE and Ti, the feathery eutectic M2C becomes thinner and shorter and tends to be isolated or distributed in a discontinuous network. (C) 2020 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.