Steel plate, and processes for preparing it, and to obtain a transition temperature from ductile to brittle (dbtt) less than approximately - 73 ° C in the heat affected zone (haz) of the steel plate.

摘要

"STEEL PLATE, AND, PROCESSES FOR PREPARING THE SAME, AND TO OBTAIN A TRANSITION TEMPERATURE FROM DUCTILE TO BREAKING (DBTT) LESS THAN APPROXIMATELY -73 ° C IN THE AREA AFFECTED BY THE HEAT OF THE STEEL PLATE" A steel " light alloy, ultra-high strength, weldable, containing less than 9% nickel by weight, with excellent firmness at cryogenic temperature on the base plate and in the heat affected zone (HAZ) when welded, having a greater tensile strength than 830 MPa and a microstructure composed predominantly of fine granulated ripped martensite and / or fine granulated lower bainite, is prepared by heating a steel plate containing iron and some or all of the additives carbon, manganese, nickel, nitrogen, copper, chromium , molybdenum, silicon, niobium, vanadium, titanium, aluminum, and boron; reduction of the plate to form a plate in one or more passages in a temperature range in which the austenite recrystallizes; finishing lamination of the plate in one or more passes in a temperature range below the recrystallization temperature and above the transformation temperature Ar ~ 3 ~; rapid cooling of the laminated finishing plate (10 '' ') to a Quenching temperature: rapid cooling stop; and tempering the plate (10 '' ') at a suitable temperature for a period of time sufficient to cause precipitation of hardening particles.