Investigating nano-precipitation in a V-containing HSLA steel using small angle neutron scattering

• Published in: Acta materialia Vol. 145; pp. 84 - 96
• Main Authors: Wang, Y.Q., Clark, S.J., Janik, V., Heenan, R.K., Venero, D. Alba, Yan, K., McCartney, D.G., Sridhar, S., Lee, P.D.
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.02.2018
• Subjects: Microalloyed steel; Precipitation; Small angle scattering; Transmission electron microscopy; Small angle scattering; Precipitation; Transmission electron microscopy; Microalloyed steel
• ISSN: 1359-6454; 1873-2453
• DOI: 10.1016/j.actamat.2017.11.032

Interphase precipitation (IPP) of nanoscale carbides in a vanadium-containing high-strength low-alloy steel has been investigated. Small angle neutron scattering (SANS) and transmission electron microscopy (TEM) were employed to characterize the precipitates and their size distributions in Fe-0.047C-0.2V-1.6Mn (in wt.%) alloy samples which had been austenitized, isothermally transformed at 700 °C for between 3 and 600 min and water quenched. TEM confirms that, following heat treatment, rows of vanadium-containing nanoscale interphase precipitates were present. Model-independent analysis of the nuclear SANS signal and model fitting calculations, using oblate spheroid and disc-shapes, were performed. The major axis diameter increased from 18 nm after 3 min to 35 nm after 600 min. Precipitate volume percent increased from 0.09 to 0.22 vol% over the same period and number density fell from 2 × 1021 to 5 × 1020 m−3. A limited number of measurements of precipitate maximum diameters from TEM images showed the mean value increased from 8 nm after 5 min to 28 nm after 600 min which is in reasonable agreement with the SANS data. [Display omitted]