Development of Hot Rolled Ribbed Bars for V-N Micro-alloyed HRB500E

The difficulty in developing the HRB500 E hot-rolled ribbed steel bars is not only to satisfy the high strength,but also ensure that the ratio of tensile/yield strength required for seismic resistance is greater than or equal to 1.25.Some domestic steel mills utilize the VN16 alloying process to produce HRB500 E,but the ratio of tensile/yield strength(R_m/R_eL) is hard to reach 1.25.In view of the above problems,the "VN16+FeV80" V-N alloying process is added to control vanadium and nitrogen contents between 0.07%～0.11% and 0.011%～0.015%,respectively.Precipitation strengthening effect of vanadium had played its role,but on the other hand,excessive precipitation of vanadium had been avoided in order to control reasonable the R_m/R_eL.Through controlling the vanadium precipitation,HRB500 E hot rolled rebars of ø12～ø32 mm specifications had been successfully developed.