Super-thick steel plate with obdurability matching and excellent high-temperature performance and manufacturing method thereof

Abstract

The invention relates to a super-thick steel plate with obdurability matching and excellent high-temperature performance and a manufacturing method thereof. The method comprises the following steps: adopting a component system of low alloy steel with medium C, high Mn and medium N as a basis; properly improving the acid soluble Als content in the steel and controlling the range of the content; controlling the ratio of Mn equivalent weight to C to between 10 and 20; alloying Cu, Ni, Cr, Mo and V; performing Nb and ultromicro Ti treatment, wherein the ratio of Nb to Ti is more than or equal to 1.50; performing Ca treatment, wherein the ratio of Ca to S is between 1.00 and 3.00; and optimizing the process of controlled rolling and subsequent heat treatment, thus the super-thick steel plate obtains excellent obdurability matching, exhaustion creep resistance, temper embrittlement resistance and welding manufacturability, in particular to excellent exhaustion creep resistance for a weldingjoint, and is particularly suitable to serve as a heat resistant pressure vessel body.

Description

technical field [0001] The invention relates to an extra-thick steel plate and a manufacturing method thereof, in particular to an extra-thick steel plate with excellent strength-toughness matching and high-temperature performance and a manufacturing method thereof. ≥300Mpa. Background technique [0002] Extra-thick steel plates for heat-resistant pressure vessel shells are medium and high-temperature structural materials that require comprehensive mechanical properties (strength-toughness matching, strong-plastic matching, and yield ratio), welding performance, and high-temperature performance. The key part of the hot pressure vessel - the carcass; during the service of the heat-resistant pressure vessel, the carcass steel plate must not only bear the structural bearing capacity and thermal stress, but also must have high thermal fatigue resistance, creep performance, temper embrittlement performance and stress Corrosion performance to improve the safety and service life o...

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Problems solved by technology

[0003] Steels for traditional medium and high temperature heat-resistant pressure vessels are generally steels containing 0.3-0.50% Mo, Cr-Mo series steels, and Mn-Ni-Mo steels. 86-87 Xishan Commemorative Technical Lectures", P259-P312), it is inevitable to add a large amount of precious alloying elements such as Cr, Mo, Ni to these steel plates; Steel plates with high Mo element content have poor surface quality of cast slabs, and generally need to go off-line for surface cleaning, and sometimes need to carry out surface coloring penetration PT inspection, slab surface grinding, hot cutting, etc.); and the steel plate The alloy content is high, the carbon equivalent Ceq and welding cold crack sensitivity index Pcm are also high, which brings great difficulties to on-site welding. Preheating is required before welding, and heat treatment is required after welding. The on-site welding environment deteriorates and welding efficiency decreases. The cost of processing and production is increased; and problems such as hydrogen corrosion, hydrogen-induced embrittlement, temper embrittlement, lamellar spalling of welded parts and creep embrittlement are prone to occur during the production and use of components

[0004] At the same time, a large number of existing patent documents only explain how to achieve the strength and low-temperature toughness of the base steel plate, improve the welding performance of the steel plate, and obtain excellent HAZ toughness in the welding heat-affected zone. The structure in the central part is fine and uniform along the thickness direction of the plate 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. Open 4-285119, special open 4-308035, flat 3-264614, flat 2-250917, flat 4-143246 "and US Patent 4855106, US Patent 5183198, US Patent 4137104 disclosed

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