Effect of Yttrium-Based Rare Earth on Inclusions and Cryogenic Temperature Impact Properties of Offshore Engineering Steel

EH36 offshore engineering steels with varied yttrium-based rare earth content were prepared by trials in industrial production. The effects of yttrium-based rare earth on the inclusions and cryogenic temperature impact properties of EH36 offshore engineering steel were investigated by scanning electron microscopy, automatic statistics of inclusions, thermodynamic analysis and fracture morphology analysis. Yttrium-based rare earth could refine the inclusions and modify irregular Al2O3 and MnS inclusions into small, spherical, regular rare earth inclusions. The optimal impact properties were found in EH36 steel with 0.020 wt.% yttrium-based rare earth. Compared with 0RE steel, the RE-inclusions were within 3 μm (91.95% of total inclusions) in diameter and were spherical or quasi-spherical when dispersed in 200RE steel. Meanwhile, the cryogenic temperature impact properties significantly increased: 200RE steel impact properties were increased by 245.1% at −80 °C

Effect of Yttrium-Based Rare Earth on Inclusions and Cryogenic Temperature Impact Properties of Offshore Engineering Steel

EH36 offshore engineering steels with varied yttrium-based rare earth content were prepared by trials in industrial production. The effects of yttrium-based rare earth on the inclusions and cryogenic temperature impact properties of EH36 offshore engineering steel were investigated by scanning electron microscopy, automatic statistics of inclusions, thermodynamic analysis and fracture morphology analysis. Yttrium-based rare earth could refine the inclusions and modify irregular Al2O3 and MnS inclusions into small, spherical, regular rare earth inclusions. The optimal impact properties were found in EH36 steel with 0.020 wt.% yttrium-based rare earth. Compared with 0RE steel, the RE-inclusions were within 3 μm (91.95% of total inclusions) in diameter and were spherical or quasi-spherical when dispersed in 200RE steel. Meanwhile, the cryogenic temperature impact properties significantly increased: 200RE steel impact properties were increased by 245.1% at −80 °C

Effect of Rare Earth Y on Microstructure and Mechanical Properties of High-Carbon Chromium Bearing Steel

The effect of rare earth Y on the microstructure and properties of high-carbon chromium bearing steel in different heat treatment processes has been studied. The microstructure and mechanical properties of the bearing steel under hot rolled, annealed and quenched and tempered conditions were compared and analysed, focusing on the effect of inclusions on fatigue performance. The addition of rare earth Y improves the microstructure, Vickers hardness, tensile strength, impact toughness and fatigue properties of bearing steel. The results show that rare earth Y can refine and spheroidise cementite, make the distribution of cementite more uniform, enhance the strengthening effect of the second phase and reduce the stress concentration caused by the shape of cementite. At the same time, the formation of network cementite is inhibited and the harm to grain boundary is reduced. It also has a refining effect on the grain, and the refined grain can achieve better mechanical properties. In addition, by modifying the oxides and sulphides in the steel, the properties of the steel are also improved, particularly in the quenched and tempered state