Super-thick quenched and tempered steel plate with good obdurability matching, and manufacturing method thereof

Abstract

The invention relates to a super-thick quenched and tempered steel plate with good obdurability matching, which is manufactured by 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 equal to (Mn equivalent weight / C)*(Ntotal-0.292Ti); controllingthe 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 1.5; performing Ca processing, wherein the ratio of Ca to S is between 0.80 and 3.00; controlling the F*DI index to be more than or equal to 0.50*the thickness of 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 to ensure 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 even and excellent obdurability / strong plastic matching and is particularly suitable for water and electricity pressure water pipes, volutes, ocean platforms and the like, is obtained, and the stable mass industrial production with low cost can be achieved.

Description

technical field [0001] The invention relates to a low-carbon (high-strength) low-alloy steel / steel plate and a manufacturing method thereof, in particular to an extra-thick quenched and tempered steel plate with good strength and toughness matching and a manufacturing method thereof, which is a low C—Mn—high Als—(Cu+Ni+Mo+Cr) alloying—(Ti+V+B) microalloying composition system through recrystallization controlled rolling + quenching and tempering process (Q+T) to obtain yield strength ≥ 500MPa, tensile strength Extra-thick quenched and tempered steel plate with strength ≥610MPa, Charpy impact energy (single value) ≥47J at -40°C, excellent weldability, and finished plate thickness ≥60mm. 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 ...

AI Technical Summary

Problems solved by technology

[0009] The object of the present invention is to provide an extra-thick quenched and tempered steel plate with good strength and toughness matching and its manufacturing method. Through the combination design of alloy elements of the steel plate and the special quenched and tempered process (RCR+QT), the excellent extra-thickness (≥ 80mm) quenched and tempered steel plate strength, low temperature toughness and strength and toughness match at the same time, the weldability of the steel plate is also excellent, and successfully solved the problem of uneven strength and toughness of extra thick quenched and tempered steel plate along the thickness direction of the steel plate

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