Modification of microstructure and mechanical properties in H13 steel by introducing oxide particles using vacuum casting

Abstract

Oxide particles with suitable size can refine the microstructure and improve the strength and toughness of steel. In this study, the particles containing Al2O3 were successfully introduced into H13 steel by vacuum casting. The micro-sized Al2O3-containg particles were randomly distributed in the dendritic structure and their number was increased by almost a factor of one. The secondary dendritic arm spacing of the ingot was decreased, which might be attributed to the heterogeneous nucleation of these oxides during solidification. Meanwhile, the alloying element segregation of the ingot was also alleviated. The micro-sized primary carbides were refined as the oxide particles were introduced to H13 steel, especially for V-rich carbides. After hot rolling and heat treatment, the size of austenitic grain was reduced by up to 75% (7.2 ± 1.8 μm), which was due to the particle stimulated nucleation and Zener pinning of micro- and nanoscale oxides in the oxide-added steel. The mechanical properties were obviously modified with the ultimate tensile strength of 1835 MPa, yield strength of 1479 MPa, tensile elongation of 13.4% and impact toughness of 24 J/cm2 after the introduction of oxide particles. It is expected that the introduction of oxide particles by vacuum casting can be applied widely in other die steel for superior performance.

Keywords

• H13 steel
• Microsegregation
• Primary carbide
• Oxide particles
• Properties