Process for producing a rolled steel product having high weldability, a high yield strength and a good notch impact toughness at very low temperatures

摘要

A process for producing rolled steel products, especially reinforcing rod for concrete or other elements to be encased in concrete and having good weldability, a high yield strength and high energy absorption for the Charpy V impact test at very low temperatures comprising forming a silicon and aluminum containing steel whose carbon content (C), manganese content (MN), and niobium content (NB) are related by the relationship set forth below. The steel blank is rolled so that the last three passes result in more than 20% of the total cross section reduction, these rolling passes are carried out so that the temperature T1 before, the temperature T2 during, and the temperature T3 after rolling are also related to the diameter D in the manner set forth below to yield a high yield strength LE and a high energy absorption expressed as KCV at -120 DEG C. The relationships are: LE=1035+510 C+192 MN+2270 NB-0.21 T1-0.42 T2-0.48 T3-3.51 D and KCV=2202-2066 C+23.20 MN-2064 NB-0.77 T1-1.24 T2-0.23 T3-1.98 D.