Ultra Low Nb (ULNb) solution for commodity grade structural steels
The construction and infrastructure sectors account for over 50% of steels produced worldwide. In 2019 this amounted to approximately 935 Mt , out of which at least 150 Mt is estimated to be in the form of hot rolled beams and sections. With a value close to US$ 100 Bn, the vast majority of this steel tonnage was produced as commodity grades with yield strengths (YS) ranging from 235 to 355 MPa and mainly in the form of light to medium sections (in kg/m terms).
Till now, Niobium usage in steel manufacturing has been synonymous to Thermo-Mechanical ( TM ) processing and High Strength Low Alloy steels, a process well-known and well-accepted by steelmakers across the world for producing high strength steels ≥355 MPa. Hence, Niobium usage has not been widely associated with commodity grades. However, with published research, ultra low Nb additions (i.e. ≤0.010wt.%) can be used to directly reduce Mn and/or eliminate V additions in such commodity grades.