Steel plate HT690 capable of being subjected to high heat input welding and manufacturing method thereof

Abstract

The invention relates to an HT690 steel plate capable of being subjected to high heat inputwelding and a manufacturing method thereof. A component system treated by low C-high Mn-(Nb+V+B) microalloying-ultramicro Ti is adopted, the acid-soluble Als content in steel is properly improved, the Als is not less than (Mn equivalent / C)*(Ntotal-0.292Ti), (Mn equivalent) / C is between 20 and 40, Pcm is not more than 0.205 percent, the Ti / N is between 2.0 and 4.0, (Cu+Ni+Mo+Cr) is alloyed and Ni / Cu is not less than 1.0, the Ca is treated and the Ca / S ratio is between 0.80 and 3.00 and the F*DI index is controlled to be not less than 0.80*finished steel plate thickness, a TMCP (Thermo-Mechanical Control Process) and a tempering process are optimized to ensure that the microscopic structure of a finished steel plate is fine tempering bainite, and the average crystal cluster size is below 25mum. The steel plate can bear high heat input welding at the same time of obtaining the properties of uniform and excellent obdurability and strong plasticity matching, is especially suitable for large steel structures of a hydroelectric pressure water pipe, a vortex, a sea platform and the like, and can realize low-cost and stable batch industrialized production.

Description

technical field [0001] The present invention relates to a steel plate that can be welded with large heat input and a manufacturing method thereof, in particular to a HT690 steel plate that can be welded with large heat input and a manufacturing method thereof. single value) ≥ 47J. 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, plasticity, toughness and weldability are the most important properties of low-carbon (high-strength) low-alloy steel, which are ultimately determined by Microstructural ...

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Problems solved by technology

In this way, the alloy content of the steel plate is high, which not only leads to high manufacturing cost of the steel plate, but also high carbon equivalent Ceq and welding cold crack sensitivity index Pcm, which brings great difficulties to on-site welding. Preheating is required before welding. After heat treatment is required, the welding cost increases, the welding efficiency decreases, and the working environment at the welding site deteriorates

A large number of existing patent documents only explain how to realize the strength and low-temperature toughness of the base metal steel plate, improve the weldability of the steel plate, and obtain excellent low-temperature toughness of the welding heat-affected zone HAZ. To ensure the strength and toughness of the steel plate and the uniformity of strength and toughness along the thickness direction of the steel plate

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