Precipitation behavior of strain-induced v precipitates in ferrite at different temperatures in a 0.2 wt% carbon steel

Abstract

The evolution of strain-induced V precipitates at two different temperatures (600 and 700°C) in ferrite was studied via atom probe tomography and transmission electron microscopy. The interpretation of experimental results is supported by simulation data, which was calculated by means of MatCalc. The study reveals that V carbonitrides are formed independently from the formation temperature. Initially, the precipitates have a higher N content than C. With longer dwell times, the C to N ratio changes from N- to C-rich V carbonitrides. At 700°C formation temperature, the growth of precipitates and the change from higher N to higher C occurs faster than at 600°C. Due to the faster growth, the V content in solid solution decreases earlier. The precipitates exhibit an elliptical shape and have NaCl type f.c.c structure. A [012]α//[011]V(C, N) and a [001] α//[011]V(C, N) orientation relationship with the ferrite matrix were detected. The aim of this work was to investigate the precipitate evolution of strain induced V particles in ferrite at 700 and 600°C by means of Transmission electron microscopy and atom probe tomography. The experimental results are compared with simulation data, which were calculated by MatCalc. During the precipitate evolution of the V carbonitrides the C/N ratio of them changes from N rich at the early stages to C rich after longer dwell times. At 700°C the precipitate evolution is faster than at 600°C. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.