| 摘要 |
<p>A method is provided for producing an ultra-high strength steel having a tensile strength of at least about 900 MPa (130 Ksi), a toughness as measured by Charpy V-notch impact test at -40 °C (-40 °F) of at least about 120 joules (90 ft-lbs), and a microstructure comprising predominantly fine-grained lower bainite, fine-grained lath martensite, or mixtures thereof, transformed from substantially unrecrystallized austenite grains and comprising iron and specified weight percentages of the additives: carbon, silicon, manganese, copper, nickel, niobium, vanadium, molybdenum, chromium, titanium, aluminium, calcium, Rare Earth Metals, and magnesium. A steel slab is heated to a suitable temperature; the slab is reduced to form plate in one or more hot rolling passes in a first temperature range in which austenite recrystallizes; said plate is further reduced in one or more hot rolling passes (10) in a second temperature range below said first temperature range and above the temperature at which austenite begins to transform to ferrite during cooling; said plate is quenched (12) to a suitable Quench Stop Temperature (16); and said quenching is stopped and said plate is allowed to air cool (18) to ambient temperature.</p> |
