High-strength extra-thick quenched and tempered steel plate with good obdurability matching and manufacturing method thereof

Abstract

The invention relates to a high-strength extra-thick quenched and tempered steel plate with good obdurability matching and a manufacturing method thereof. The manufacturing method comprises the following steps: adopting a component system of low C-Mn-(Ti+V+B) micro-alloyed steel as a basis to appropriately increase the content of acid soluble Als in the steel, wherein the Als is more than or equalto (Mn equivalent weight / C)*(Ntotal-0.292Ti); controlling the ratio of (Mn equivalent weight) to C to between 10 and 30; alloying (Cu+Ni+Mo+Cr), wherein Ni / Cu is more than or equal to 1.0; performingCa processing, wherein the ratio of Ca to S is between 0.80 and 3.00, and (Ca)(S)<0.18> is less than or equal to 2.5*10<-3>; controlling the F*DI index to be more than or equal to 0.65*the thicknessof a finished steel plate and other metallurgy technological means; and performing optimization, crystallization and controlled rolling, and performing a quenching and tempering process (Q+T) so as toensure that the microscopic structure of the finished steel plate is a tiny tempered bainite (probably containing a minute quantity of ferrite), and the average crystal group size is below 25 mum. Through the method, a large-scale steel structure, which has excellent obdurability / strong plastic matching and even mechanical property along the plate thickness direction and is particularly suitablefor water and electricity pressure water pipes, volutes, ocean platforms and the like, is obtained.

Description

technical field [0001] The invention relates to a quenched and tempered steel plate and a manufacturing method thereof, in particular to a high-strength extra-thick quenched and tempered steel plate with good strength and toughness matching and a manufacturing method thereof. Background technique [0002] As we all know, low-carbon (high-strength) low-alloy steel is one of the most important engineering structural materials, widely used in oil and gas pipelines, offshore platforms, shipbuilding, bridge structures, boiler containers, building structures, automobile industry, railway transportation and machinery manufacturing. middle. The properties of low-carbon (high-strength) low-alloy steel depend on its chemical composition and the process system of the manufacturing process, among which strength, toughness and weldability are the most important properties of low-carbon (high-strength) low-alloy steel, which are ultimately determined by the finished steel state of the mi...

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Problems solved by technology

[0008] The object of the present invention is to provide a high-strength extra-thick quenched and tempered steel plate with good strength and toughness matching and its manufacturing method. Through the combination design of steel plate alloy elements and special quenched and tempered process (RCR+QT), the excellent extra-thickness ( ≥60mm) quenched and tempered steel plate strength, low temperature toughness and toughness match, the weldability of the steel plate is also excellent, and solve the problem of uneven strength and toughness of extra thick quenched and tempered steel plate along the thickness direction of the steel plate; its tensile strength ≥650MPa, Tensile strength ≥ 650MPa, Charpy impact energy (single value) ≥ 47J at -40°C, excellent weldability; at the same time, good weldability saves the cost of steel component manufacturing for users, shortens the time for steel component manufacturing for users, and provides customers with created great value

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