PRODUCTION METHOD OF THICK ROLLED PLATES OF STRENGTH CLASSES K52-K60, X52-X70, L360-L485 TO MANUFACTURE ELECTRIC WELDED PIPES OF MAIN PIPELINES Russian patent published in 2015 - IPC B21B1/32 C22C38/38 C22C38/40 C22C38/58 

FIELD: metallurgy.

SUBSTANCE: method includes manufacturing of rolled steel plates, containing in wt %: carbon 0.03-0.11, silicon 0.15-0.45, manganese 1.40-1.95; chrome 0.01-0.30, nickel 0.01-0.30, copper 0.01-0.30, molybdenum 0.01-0.30, aluminium 0.02-0.05, niobium 0.03-0.07, vanadium 0.001-0.10, titanium 0.010-0.035, sulphur 0.0005-0.003, phosphorus 0.002-0.015, nitrogen 0.001-0.009, iron and inevitable admixtures - rest, at that carbon equivalent C_E is: C_E=0.0005σ_t+0.09±0.04, where σ_t is rated value of ultimate transient tensile strength, N/mm². Ratio of semifinished rolled stock for final rolling is determined as follows: H_s/H_rr=(0.0080σ_y+0.1)±0.5, where σ_y is rated yield strength of rolled product, N/mm²; Hs_п is thickness of semifinished rolled stock for finished rolling, mm; H_rr is thickness of ready rolled product, mm. Process diagram of rolling is selected depending on design factor K determined by equation K=σ_t×H, where H is rated thickness of ready rolled product, mm. At K below 11000±2000 N/mm the controlled rolling with air cooling is accepted, at K over 11000±2000 N/mm controlled rolling with accelerated cooling is accepted.

EFFECT: rolled plates manufacturing of strength classes K52-K60, X52-X70, L385-L485 for electric welded pipes of main pipelines with increased mechanical characteristics.

2 cl, 1 tbl