HIGH STRENGTH STEEL PLATE AND HIGH STRENGTH GALVANISED STEEL PLATE WITH GOOD FORMABILITY AND METHODS OF THEIR MANUFACTURING

摘要

FIELD: metallurgy.SUBSTANCE: plate is made from steel containing in wt %: C: from 0.075 to 0.30, Si: from 0.30 to 2.50, Mn: from 1.30 to 3.50, P: from 0.001 to 0.030, S: from 0.0001 to 0.010, Al: from 0.005 to 1.50, Cu: from 0.15 to 2.0, N: from 0.0001 to 0.010, O: from 0.0001 to 0.010, additionally, if necessary, Ti: from 0.005 to 0.15, Nb: from 0.005 to 0.15, B: from 0.0001 to 0.010, Cr: from 0.01 to 2.0, Ni: from 0.01 to 2.0, Mo: from 0.01 to 1.0, W: from 0.01 to 1.0, V: from 0.005 to 0.15 and one or more of Ca, Ce, Mg and REM: in total from 0.0001 to 0.5, iron and inevitable admixtures - rest. Plate has microstructure containing ferrite phase and martensite phase. Share of Cu particles, not coherent with volume-centred cubical lattice (bcc) of iron is 15% or over relatively to all Cu particles, density of Cu particles in the ferrite phase is 1.0×10/mor over, and mean size of Cu particles in the ferrite phase is 2.0 nm or over.EFFECT: high strength with maximum ultimate tensile strength 900 MPa or over and high formability.10 cl, 22 tbl