Steel reinforcing bars for concrete - with shaped surface conformation for improved bonding produced by cold deformation to ensure good mechanical properties

摘要

Steel reinforcement bars of approx. round cross-section partic. for reinforcement mats are mfd. in which steel hot-rolled bars are cold deformed to produce a surface structure strengthening the bond in concrete, partic. with ribs or contours, whereby the surface deformation is in several axially parallel areas distributed over the bar circumference. The starting material is a steel with at least the following compsn.: 0.06-0.18% C, 0.01-0.10% Si (semi-killed) or 0.10-0.6% Si (killed steel), 0.30-1.50% Mn, 0.00-0.06% P, 0.00-0.05% S, 0.00-0.01% N (0.00-0.013% electric steel), 0.02-0.15% Nb, or 0.02-0.20% V, in which Si can be replaced with equivalent part of Al, and Nb and/or V with Cr and/or Ni and/or Ti. Hot rolled bars receive 15-25% volume change with respect to their original length, including the surface deformation, by cold working. Assurance of required tolerances and mechanical properties through the cold forming process, over a wider range of diameters than previously.