Investigation on Improved Hot Processing Map of Cr₄Mo₄Ni₄V Aerospace Bearing Steel Based on Carbide Content

Cr₄Mo₄Ni₄V steel has excellent fracture toughness and fatigue life, which is one of the main materials for the new generation of aeroengine bearing rings. However, there is still lack of investigation on hot processing of Cr₄Mo₄Ni₄V steel up to now. Herein, the hot processing map is established based on systemic compression tests; then, according to the requirements of Cr₄Mo₄Ni₄V steel for carbide content, improved hot processing map is established based on the carbide content by superimposing the carbide content zoning map. Results reveal that the activation energy is 304.9 kJ mol⁻¹, and power dissipation value increases only within the strain range of 0.2–0.4, while the instability zone always moves toward the direction of high strain rate with the increase of strain. In 900–1150 °C, 0.01–5 s⁻¹, the content of carbide could be divided into three zones: little dissolved zone, mostly dissolved zone, and completely dissolved zone. Improved hot processing map indicates that the ideal processing domain is 950–1050 °C, 0.01–0.3 s⁻¹ etc.