Thick steel plate for low temperature use and capable of being welded in superhigh energy and its production process

Abstract

The thick steel plate for low temperature use and capable of being welded in superhigh energy has the material comprising C 0.030-0.050 wt%, Si not more than 0.2 wt%, Mn 1.50-1.80 wt%, P not more than 0.01 wt%, S not more than 0.002 wt%, Nb 0.010-0.020 wt%, Als 0.040-0.060 wt%, Ti 0.008-0.012 wt%, N not more than 0.0035 wt%, Ca 0.001-0.005 wt%, B 0.001-0.003 wt%, and Fe and inevitable impurity for the rest, with Pcm not more than 0.18 wt%. The present invention has low alloy steel as basis, properly raised Als content, C / Mn ratio of 0.020-0.050, Ti-B microalloying, Ca or REM treatment, Ti / N ratio of 3.0-3.5, optimized TMCP treatment, microscopic structure comprising small amount of ferrite and diffused bainite crystal of average crystal grain size below 15 micron, excellent mechanical performance and welding performance, and is especially suitable for being used as high strength ship deck, low temperature pressure container, offshore platform, etc.

Description

technical field [0001] The invention relates to a thick steel plate with a yield strength ≥ 415 MPa in a low C-high Mn-high Als-Ti-B alloy system that can be welded with super large heat input 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, bridges, pressure vessels, building structures, automobile industry, railway transportation and machinery manufacturing . 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 microstructure. With the continuous development of science and tech...

AI Technical Summary

Problems solved by technology

[0005] However, the C / Mn of the above-mentioned thick steel plates used in the world is generally low, generally above 0.05, and there is no special composite Al, Ti, B, N microalloying treatment, which is reflected in the absence of Al, Ti, B, The quantitative relationship between N makes the low-temperature toughness (below -50°C) of the thick steel plate unstable, especially the low-temperature toughness of the heat-affected zone (HAZ) of the welded steel plate is low, which makes the thick plate unable to withstand super-large heat input welding, thus affecting the steel structure. Manufacturing efficiency and scope of application

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