Superhardenability behavior of vanadium in 40CrNiMoV steel

• Superhardenability behavior was obtained in the steel containing vanadium.
• Al was used to stabilize nitrogen to prevent the formation of VN.
• The segregation of vanadium in austenite grain boundaries was characterized.
• A novel characterization for alloys on influencing hardenability was put forward.
• Excellent mechanical properties were obtained in the steel containing vanadium.

The effects of vanadium on the hardenability, microstructures and mechanical properties of 40CrNiMoV steel were investigated after stabilizing nitrogen with aluminum by using an electron microprobe, a scanning electron microscope, a transmission electron microscope, and a hardness tester, etc. The existence state of vanadium in steel was also analyzed. Results showed that aluminum can effectively stabilize nitrogen by producing aluminum nitride. This phenomenon promoted the segregation of solid solution vanadium in grain boundaries, delayed the transformation of ferrite and improved the stability of austenite. Thus, vanadium can potentially improve the hardenability of steels. Excellent mechanical properties of 40CrNiMoV steel were obtained during slow cooling with the addition of vanadium, and this process can be used to produce heavy section steel components.

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