Development of Low Carbon Boron Steel for Wire Drawing
From the mechanical point of view, the successful cold drawing of wire-rods of low carbon steel requires a high ductility and a ratio between the yield stress and tensile strength as lowest as possible, both for diminish the fractures during the process. Small boron additions in the cast of this kind of steel produce an increase in the size of austenitic grain, and consequently the ferritic one, and a diminution of the deformation hardening due to the reduction in the nitrogen content in the solid solution. In this way, the goal of this work is to study the effect of small boron additions (67 to 117 ppm) in the mechanical properties of 5.5 mm diameter wire-rods of low carbon steel. The wire-rods were characterized by means of traction tests, metallographic analysis with optic and electronic microscopy, and the results were compared with the corresponding one for wire-rod of standard steel, i.e., without boron contents. The metallographic analysis confirms the increase in size of ferritic grain. The measured ductility present only slight increases in boron steel, no significant from the quality point of view, however, the ratio between yield stress and tensile strength in boron steels shown a clear improvement respect to the standard. Traction tests in samples obtained at the exit of each one of the matrixes used during the cold drawing process shows an improve in the behavior of low carbon steel with boron contents.
T. Chandra, K. Tsuzaki, M. Militzer , C. Ravindran
C. Camurri et al., "Development of Low Carbon Boron Steel for Wire Drawing", Materials Science Forum, Vols. 539-543, pp. 4238-4242, 2007