Effect of Cerium-based Inoculant Addition on the Development of Microstructure and Mechanical Properties of Centrifugally Cast High-speed Steel

As is widely known, the refinement of microstructure positively affects a wide range of material properties. In foundry practices, grain refinement techniques are frequently used for these purposes. This contribution involves the testing of a cerium-based inoculant on a high-speed steel alloy, used for producing the working layers of centrifugally cast rolls for hot rolling sheet metal. As part of the study, two rolls were cast using the traditional centrifugal casting method: the working layer melt of one roll was not inoculated, while the working layer melt of the other roll was inoculated with a cerium-based inoculant. As a part of experimental work, simulations were performed using Thermo-Calc under equilibrium and Scheil-Gulliver solidification models. Samples in the cast state were analysed using optical and SEM microscopy. After heat treatment, specimens for mechanical property testing were prepared from the machined segments of the rolls. The analysis revealed that the addition of the inoculant had the most significant effect on the size, shape, and distribution of MC carbides, while it did not affect the refinement of the microstructure. There were no significant impacts on the mechanical properties, except for the value of the modulus of elasticity. The most notable effect was on the amount of worn material in the Pin-on-Disc test, where the inoculated roll demonstrated significantly better performance.