METHOD OF MANUFACTURING OF HIGH STRENGTH MARTENSITE STEEL, AND PLATE PRODUCED USING THIS METHOD Russian patent published in 2015 - IPC C21D8/02 C21D6/02 C22C38/04 

FIELD: metallurgy.

SUBSTANCE: semifinished steel contains in wt %: 0,15 ≤ C ≤ 0.40, 1.5 ≤ Mn ≤ 3, 0.005 ≤ Si ≤ 2, 0.005 ≤ Al ≤ 0.1, S ≤ 0.05, P ≤ 0.1, 0.025 ≤ Nb ≤ 0.1 and optionally: 0.01 ≤ Ti ≤ 0.1, 0 ≤ Cr ≤ 4, 0 ≤ Mo ≤ 2, 0.0005 ≤ B ≤ 0.005, 0.0005 ≤ Ca ≤ 0.005, Fe and inevitable admixture the rest, is heated to temperature T₁ from 1050° to 1250°C, then roughing is performed at temperature T₂ from 1050° to 1150°C, with total reduction coefficient ε_a over 100% with production of the plate with incompletely recrystallized austenite structure with average grain size below 40 microns. The plate is cooled to temperature T₃ from 970° to Ar3+30°C with rate V_R1 exceeding 2°C/s, then hot finish rolling of this cooled plate is performed at temperature T₃ with total reduction coefficient ε_b over 50% to produce plate, then plate is cooled with rate V_R2 exceeding critical rate of hardening to martensite.

EFFECT: increased mechanical strength, assurance of elastic strength over 1300 MPa.

5 cl, 1 ex