Influence of Boron on Mechanical Properties and Microstructures of Hot-Rolled Interstitial Free Steel
This paper examines an effect of boron (B) on dynamic softening behavior, mechanical properties and microstructures for Nb-Ti added high strength interstitial free (IF) steel. For this purpose, IF steels containing 0ppm B, 5ppm B and 30ppm B were chosen. Continuous cooling compression test was performed to investigate dynamic softening behavior. Mechanical properties and microstructures of pilot hot-rolled IF steel sheet were analyzed by uni-axial tensile test and electron back-scattered diffraction (EBSD). It was found that no-dynamic recrystallization temperature (Tndrx) which can be determined from the relationship between flow stress and temperature is a constant of 955oC for all IF steels. However, an addition of B into IF steels increases work hardening rate at the temperature below Tndrx. It was also verified that B retards phase transformation of austenite into ferrite. EBSD analysis revealed that absence of B induces fine ferrite grain size and many high angle grain boundaries.
Paul Van Houtte and Leo Kestens
S.I. Kim et al., "Influence of Boron on Mechanical Properties and Microstructures of Hot-Rolled Interstitial Free Steel ", Materials Science Forum, Vols. 495-497, pp. 537-542, 2005