Significantly improved oxidation and thermal shock resistances of 414N hard-faced layer by microalloying and its mechanism

In this paper, the Ti/Nb/V and Ce microalloyed MA414N welding wire was used to weld the hard-faced layer of continuous casting roller, the oxidation and thermal shock resistances of the MA414N hard-faced layer were compared with 414N without microalloying, and TEM, SEM/EDX, XPS techniques were used to investigate the effect of microalloying on oxidation and thermal shock resistances and its mechanism. It was found that the oxidation and thermal shock resistances of MA414N were significantly improved, in compare with 414N. For the MA414N sample after oxidation for 360 h at 650 °C, the oxidation weight gain and oxidation rate constant of were respectively reduced by 16% and 31%, in compare with 414N; Compared to 414N, the surface damage factor of the MA414N sample after 300 thermal fatigue cycles was significantly reduced by 53%. Thermal fatigue crack initiation and propagation were affected by thermal stress, microstructure stress and oxidation, the greatly improvement of thermal shock resistance of MA414N is mainly due to the following factors: during the thermal shock, (i) the in-situ precipitation of the second phase induce high temperature self-reinforced, (ii) less \mathrmM \rightleftharpoons \mathrmA transformation leads to relatively small microstructure stress, and the more stable oxide film is formed on its surface.