Effects of Boron Addition on Undercooled Austenite Transformation of Low Carbon Mn-Nb Steels

The effects of boron on the undercooled austenite transformation of low carbon Mn-Nb steels during continuous cooling were investigated in this study. Five kinds of steel specimens were fabricated by varying boron contents. Continuous cooling transformation (CCT) curves of the investigated steels under deformed conditions were constructed by a combination of deformation dilatometry and metallographic methods. The results indicated that a small amount of boron efficiently increased the hardenability of steels and lowered transformation temperature, which leading to a finer bainite microstructure and an increase in hardness.