Effect of rare earth Ce on cleanliness, mechanical properties and wear resistance of low alloy wear-resistant steel

To develop a wear-resistant steel with excellent mechanical properties and superior wear resistance, low alloy wear-resistant steels with different contents of rare earth were prepared through induction smelting, rolling, quenching, and tempering. The effects of Ce on the inclusion characteristics, mechanical properties, and wear resistance of the test steels were investigated through scanning electron microscopy and energy dispersive X-ray spectroscopy, mechanical property testing, and impact abrasive wear testing. The results indicated that adding Ce to the low alloy wear-resistant steel significantly reduced the number and size of inclusions. When the Ce content reached 0.0037 wt.%, irregular Al₂O₃ and MnS inclusions were significantly reduced and were replaced by nearly spherical Ce₂O₂S, CeS, and CeP inclusions. The comprehensive mechanical properties including the strength, post-fracture elongation, Brinell hardness, and impact toughness of the test steels were enhanced in various degrees. In particular, the low-temperature impact toughness of the test steels increased from 18 to 39 J as the Ce content rose from 0 to 0.0037 wt.%. The wear mass loss of the test steel gradually decreased with increasing the Ce content, indicating that the addition of Ce significantly enhances the wear resistance of low alloy wear-resistant steel. Under impact loading, a plastic deformation zone called sub-surface layer with a thickness of 10–30 μm formed on the worn surface. Work hardening from the plastic deformation strengthened the microhardness of the sub-surface layer, thus improving the wear resistance of the test steel. With increasing the Ce content, the wear resistance of the test steel further improved due to thickening the sub-surface layer.