80 kg class ultra-high toughness, extremely thick steel plate and manufacturing method thereof

Abstract

The invention discloses a 80Kg grade steel plate with ultrahigh toughness and extreme thickness and a manufacturing method of the steel plate. The steel plate comprises the following components in percentage by weight: 0.08-0.13% of C, Si smaller than or equal to 0.10%, 0.80-1.20% of Mn, P smaller than or equal to 0.013%, S smaller than or equal to 0.0030%, 0.20-0.45% of Cu, 1.00-1.60% of Ni, 0.35-0.65% of Cr, 0.30-0.60% of Mo, 0.040-0.070% of Als, 0.010-0.030% of Nb, 0.030-0.060% of V, 0.004-0.010% of Ti, N smaller than or equal to 0.0050%, 0.001-0.004% of Ca, 0.0008-0.0016% of B, and balance of Fe. According to the manufacturing method, a component system of low C-ultralow Si-medium Mn-(Ti+V+Nb+B) microalloyed steel is used as a basis, special rolling control and offline gradient tempering technology (QQ+T) are optimized, so that microstructures of the produced steel plate are small tempered bainite+ tempered martensite, the average crystal colony size is less than 20 microns, excellent obdurability and plasticity match is obtained, and mechanical performance in the direction of the thickness of the steel plate is uniform.

Description

technical field [0001] The present invention relates to the manufacturing technology of low-carbon, high-strength and low-alloy steel, in particular to 80-kilogram class ultra-high toughness, ultra-thick steel plate and its manufacturing method. 5 ≥18%, -60°C Charpy transverse impact energy (single value) ≥70J, excellent weldability, Charpy impact energy (single value) of welding heat affected zone (HAZ) at -60°C ≥47J, 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 manufacturing process, among which stren...

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Problems solved by technology

[0007] The purpose of the present invention is to provide a kind of 80 kilogram class ultra-high toughness, extremely thick steel plate and its manufacturing method, through the combined design of steel plate alloy elements and special manufacturing process (CR+QQT), when obtaining excellent extra thick (≥100mm ) Quenched and tempered steel plate strength, ultra-low temperature toughness and strength and toughness matching, the weldability of the steel plate is also excellent, and successfully solved the problem of uneven strength and toughness of the extra thick quenched and tempered steel plate along the thickness direction of the steel plate

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