Forging and forgings manufactured from high-grade structural steel of bainite structure, high-grade structural steel of bainite structure

摘要

The present invention provides a steel having a high strength and a small tendency to bend without requiring a complicated heat treatment process. To this end, the engineering steel according to the present invention comprises at most 0.25% C, 1.5% Si, 0.20-2.00% Mn, 4.00% Cr, 0.6-3.0% Mo, 0.004-0.020 % Of N, at most 0.40% of S, 0.001-0.035% of Al, 0.0005-0.0025% of B, at most 0.015% of Nb, at most 0.01% of Ti, at most 0.10% of V, at most 1.5% of Ni, % Al,% Nb content% Nb,% Ti content,% V content and% N content N of the engineering steel. % Al / 27 +% Nb / 45 +% Ti / 48 +% V / 25% N / 3.75. The yield strength of the engineering steel according to the present invention is at least 750 MPa, the tensile strength is at least 950 MPa, and at least 80% by volume of bainite and at most 20% by volume of residual austenite, ferrite, perlite and / or martensite Respectively. According to the characteristic profile of the steel according to the present invention, the engineering steel according to the present invention is suitable for manufacturing a product whose cross section greatly changes over the entire product length, by forging technique. The present invention discloses a method for manufacturing such forgings.