Alloy steel for high-pressure container and preparation method thereof

Abstract

The invention relates to alloy steel for a high-pressure container. The alloy steel comprises the following components in percentage by weight: 0.27 to 0.33 percent of C, 0.60 to 1.00 percent of Mn, 1.40 to 1.70 percent of Si, less than or equal to 0.003 percent of S, less than or equal to 0.006 percent of P, 0.80 to 1.20 percent of Cr, 0.30 to 0.50 percent of Mo, 0.10 to 0.15 percent of V and the balance of Fe and inevitable impurities, wherein the total content of impurity elements and gas, namely, S+P+H+O+N is less than or equal to 100 ppm. In the smelting process of the invention, the form of electric furnace or electric furnace and electroslag remelting is replaced by the form of vacuum induction furnace and consumable electrode vacuum furnace, so that the problem of low toughness, particularly low fracture toughness caused by the low impurity of an original type of steel; in a processing procedure, high-speed forging or steam hammering of which the processing ratio is more than 5 is replaced by high-speed forging and radial forging of which the processing ratio is more than 10, so that the problems of non-uniform grain size and structure caused by non-uniform forging of the original type of steel are solved; and in a thermal refining process, the form of quenching and high temperature tempering is replaced by the form of quenching and low temperature tempering, and the sorbite structure of the original type of steel is replaced by a martensite structure, so that the problem of insufficient intensity is solved.

Description

technical field [0001] The invention relates to compositional design and manufacture of alloy structural steel, in particular to alloy steel for high-pressure vessels such as autoclaves and storage tanks and a manufacturing method thereof. Background technique [0002] Steel for high-pressure vessels belongs to alloy structural steel. According to the different conditions of use (working environment), the steel for high-pressure vessels can be divided into medium and low-grade steel for high-pressure vessels, and high-grade steel for high-pressure vessels. [0003] At present, most of the steels used for high-pressure vessels in my country are low- and medium-grade steels for high-pressure vessels. Among them, low-grade steels generally use CrMn, CrMnSi, and CrNiMo low- and medium-carbon low-alloy structural steels (the alloy content does not exceed 5%, and its strength is low. (300-600MPa), due to the general ladle refining process, the manufacturing cost is also very low; ...

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Problems solved by technology

[0013] On the basis of 30CrMnSiA alloy steel, Mo, V elements and Si content are added to solve the problems of insufficient penetration of the original steel, coarse grains, and easy embrittlement after tempering; the smelting process is composed of "vacuum induction furnace + vacuum self-consumption Furnace" to replace the original "electric furnace or electric furnace + electroslag remelting" to solve the problem of toughness, especially low fracture toughness caused by insufficient purity of the original steel; the processing technology is changed from "fast forging + radial forging, and the processing ratio is greater than 10 "Replacing the original "fast forging or steam hammer, the processing ratio is greater than 5" to solve the problem of uneven grain size and structure of the original steel due to uneven forging; the quenching and tempering treatment is changed from "quenching + low temperature tempering" Instead of "quenching + high temperature tempering", the martensitic structure is used to solve the problem of insufficient strength caused by the sorbite structure of the original steel type. This quenching and tempering process is an indispensable element to achieve the expected quality effect with the steel type of the present invention

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