Isothermal Precipitation Behavior of Vanadium Carbonitride in V‐, N‐Added Low‐Carbon Steel

Herein, the isothermal precipitation behaviors of V(C,N) in ferrite are studied. At 700 °C, the dominant precipitation behavior of V(C,N) is interphase precipitation (IP), whereas at 660 and 620 °C, random precipitation (RP) is dominant. Both IP and RP show the Nishiyama–Wassermann orientation relationship (OR) with ferrite, unlike the common OR between precipitation and ferrite. The size of most precipitated particles varies in the ranges of 5–8 nm at 660 °C and 3–5 nm at 620 °C. The average values of hardness of ferrite grain formed at 700, 660, and 620 °C are 195.1, 237.6, and 278.6 HV, respectively. The dominant precipitation behavior of V(C,N) in V–N microalloyed steel is interphase precipitation at 700 °C and random precipitation at 660 and 620 °C, and the precipitated particles show Nishiyama–Wassermann orientation relationship with ferrite. The average hardness of ferrite grain formed at 700, 660, and 620 °C is 195.1, 237.6, and 278.6 HV, respectively.