Super-thick quenched-tempered steel plate with 60kg-grade tensile strength and production method of the super-thick quenched-tempered steel plate

Abstract

The invention discloses a super-thick quenched-tempered steel plate with 60kg-grade tensile strength and a production method of the super-thick quenched-tempered steel plate. The production method includes the means as follows: adopting a component system of low C-Mn-(Ti plus Nb plus V plus B) micro-alloy steel as base, appropriately improving the content of acid solution Als which is greater than or equal to (Mn equivalent / C) * (Ntotal minus 0.0292Ti); controlling (Mn equivalent) / C to be greater than or equal to 15, alloying (Cu plus Ni plus Mo plus Cr); controlling Ni equivalent to be greater than or equal to 0.90%, Mo equivalent to be greater than or equal to 0.25%, and Nb / Ti to be between 1.0 and 2.5; conducting Ca treatment, and controlling the ratio of Ca / S to be between 0.80 and 3.00, (Ca)*(S)0.18 to be less than or equal to 2.5*10 minus 3, and F*DI index to be greater than or equal to 0.65* thickness of a finished steel plate. Optimization control rolling plus an off-line special quenching-tempering technology enable the microstructural of the finished steel plate to be tiny tempering bainite plus tempered martensite, the average colony size is below 25 Mum, excellent matching of strong toughness / strong plasticity is obtained and the mechanical property along the direction of the thickness of the plate is uniform; the super-thick quenched-tempered steel plate with 60kg-grade tensile strength is specially applicable to large-sized steel structures and equipment such as water-electricity penstocks, volutes, ocean platforms, large-sized engineering machinery and can realize low-cost industrial production in stable batches.

Description

technical field [0001] The present invention relates to a quenched and tempered steel plate and a manufacturing method thereof, in particular to a 60-kg super-thick quenched and tempered steel plate and a manufacturing method thereof, the tensile strength of which is 610MPa to 730MPa, the yield strength ≥ 490MPa, and the Charpy transverse impact energy at -40°C (single value ) ≥ 80J, super thick quenched and tempered steel plate with excellent weldability, finished plate thickness ≥ 100mm. 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 man...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a kind of ultra-thick quenched and tempered steel plate with a tensile strength of 60 kg and its manufacturing method. Through the combined design of steel plate alloy elements, controlled rolling process and special quenched and tempered process, excellent extra thickness ( ≥100mm) quenched and tempered steel plate strength, low temperature toughness and toughness matching, 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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