Hot-work die steel with superior mechanical properties at room and high temperatures prepared via a combined approach of composition design and nanoparticle modification

Abstract

Hot-work die steel with excellent strength and toughness can improve the precision of the die and prolong its service life. However, this is very difficult to achieve because of the opposing relationship between strength and plasticity. In this paper, we propose a combined approach of composition design and nanoparticle modification to overcome this difficulty. A novel hot-work die steel with reinforced trace nano-(TiC–TiB2) was fabricated using a traditional method. It had an improved microstructure, which consists of fine martensitic laths with high dislocation density, abundant small precipitates, and small and dispersed residual austenite. This expected microstructure improved the work hardening and uniform deformation ability of the steel, resulting in superior comprehensive mechanical properties. The yield strength and impact toughness of the novel hot-work die steel at room temperature were 1464 MPa and 597 J/cm2, respectively, increases of 121 MPa and 265 J/cm2, respectively, compared to the values for advanced and widely used traditional H13 steel. In particular, the impact toughness of the novel hot-work die steel at room temperature was approximately 42.5% and 33.0% higher than the impact toughness of H13 containing 0.01 and 0.02 wt% nanoparticles, respectively. Furthermore, the yield strength, ultimate tensile strength, and elongation of novel hot-work die steel at 500 °C were 1078 MPa,1103 MPa, and 40.4%, respectively, increases of 85 MPa, 86 MPa, and 4.2%, respectively, compared to values of the blank that was used in this work. This work shows new prospects for the development of hot-work die steel with excellent strength and toughness.

Keywords

• Novel hot-work die steel
• Composition design
• Nanoparticle modification
• Superior mechanical properties