Kinetics of ferrite to Widmanstätten austenite transformation in a high-strength low-alloy steel revisited

Abstract

Abstract Growth kinetics of Widmanstätten austenite in ferrite in a Fe–C–Mn–Nb high strength low-alloy steel is studied. It is based on the model developed by Ivantsov, Horvay and Cahn, and Trivedi (HIT theory) that describes diffusion-controlled growth of precipitates with shapes approximating to needles or plates. The calculated results using HIT theory with experimental values of the radius of the advancing tip agree well with the experimental observations. It is found that the ratio between calculated and experimental values of the radius of the advancing tip is inversely proportional to the degree of supersaturation. The influence from transformation strain/stress and/or anisotropy of interphase energy on precipitate morphology, which was ignored in the development of HIT theory, is discussed.