Effects of hot rolling and titanium content on the microstructure and mechanical properties of high boron Fe-B alloys

High boron Fe-B alloys (1.8 wt.% B) with different titanium contents are fabricated by Vacuum Induction Melting (VIM) technique. The integrated mechanical properties of the as-cast alloys are poor, especially the ductility. In this investigation, hot-rolling technology is used to improve the microstructure and mechanical properties. The microstructure analysis shows that hot rolling can reduce the size and improve the distribution of the reinforcements. The mechanical properties testing indicates that the yield strength is unchanged basically, but the tensile strength and elongation are improved greatly by hot rolling, especially the elongation. The content of titanium also has great effects on the microstructures and mechanical properties of the hot-rolled alloys. For the hot-rolled alloys, with the titanium content increasing, the ultimate tensile strength and yield strength first decrease slightly and then increase. The elongation and impact toughness are improved significantly. In particular, when the atomic ratio of Ti to B is 0.5, the reinforcements are almost entirely TiB2 and uniformly distributed in the Fe-matrix. The ternary Fe-B-Ti alloy exhibits balanced mechanical properties: yield strength, ultimate tensile strength, elongation and impact toughness are 334 MPa, 602 MPa, 16.2% and 213 kJ/m(2), respectively. (C) 2011 Elsevier Ltd. All rights reserved.