Acta Metallurgica Sinica (English Letters) ›› 2025, Vol. 38 ›› Issue (9): 1591-1603.DOI: 10.1007/s40195-025-01881-7

Previous Articles     Next Articles

A Novel Nano-Structured Die Steel with High Strength and High Thermal Stability

Xinhao Li1, Jieli Ma1, Yiren Wang1, Yong Jiang1,2()   

  1. 1 School of Materials Science and Engineering, Central South University, Changsha, 410083, China
    2 State Key Laboratory for Powder Metallurgy, Central South University, Changsha, 410083, China
  • Received:2025-01-23 Revised:2025-02-23 Accepted:2025-03-19 Online:2025-09-10 Published:2025-06-12
  • Contact: Yong Jiang, yjiang@csu.edu.cn

Abstract:

A novel oxide-dispersion-strengthened (ODS) die steel was fabricated by mechanical alloying and hot consolidation. Annealing and quench-tempering treatments both obtained an ultra-fine grain structure (mean size: 310-330 nm) with an ultra-high density of ultra-fine Y-Al-O nano-oxides (number density: ~ (1-1.5) × 1023 m−3, mean size: 5.1-7.2 nm). Prolonged thermal exposure further induced the new, highly dense precipitation of ultra-fine Y-Zr-O nano-oxides. Both nano-oxides tended to be wrapped up with a B2-NiAl nano-shells. Although the quench-tempered sample showed much higher room-temperature strength (yield strength = 1393 ± 40 MPa and ultimate tensile strength = 1774 ± 11 MPa) and slightly lower elongation (elongation = 13.6% ± 0.6%) than the annealed sample (YS = 988 ± 7 MPa, UTS = 1490 ± 12 MPa, and EL = 15.2% ± 1.1%), both samples exhibited better strength-ductility synergy at room temperature and much higher thermal stabilities at high temperatures (600-700 °C) than all those conventional hot-work die steels, which makes the new ODS steel highly promising for advanced hot-work mold and die applications at high temperatures above 600 °C.

Key words: Hot-work die steel, Oxide-dispersion-strengthened, Nano-structure, Core-shelled, Thermal stability