HIGH-STRENGTH HOT-STEEL STEEL WITH HIGH SHOCK STRENGTH AND TEMPORARY RESISTANCE OF 800 MPA AND METHOD OF ITS PRODUCTION

摘要

A high-toughness hot-rolled high-strength steel with a yield strength of Grade 800 MPa with its chemical components, in weight percentages, being C 0.02-0.05%, Si≤0.5%, Mn 1.5-2.5%, P≤0.015%, S≤0.005%, Al 0.02-0.10%, N≤0.006%, Nb 0.01-0.05%, Ti 0.01-0.03%, 0.03%≤Nb+Ti≤0.06%, Cr 0.1%-0.5%, Mo 0.1-0.5%, B 0.0005-0.0025%, and the balance of Fe and unavoidable impurities, and a preparation method thereof. The present invention acquires, via direct quenching, an ultra-low carbon martensite structure with a yield strength of 800 Mpa and an impact energy of more than 100J under a temperature of −80° C.