Sulfuric acid resistant ferritic stainless steel and manufacturing method thereof

Abstract

The invention relates to a sulfuric acid resistant ferritic stainless steel and a manufacturing method thereof. The sulfuric acid resistant ferritic stainless steel comprises the following chemical components by weight: 0.002-0.015% of C, 0.002-0.015% of N, 0.2-1.0% of Si, 0.2-0.5% of Mn, less than or equal to 0.030% of P, less than or equal to 0.003% of S, 28-30% of Cr, 1.5-3% of Ni, 2.0-4.0% of Mo, 0.1-0.3% of V, 0.10-0.30% of Ti, 0.2-0.5% of Nb, 0.05-0.1% of Al, with the sum of Cr+3.3*Mo being greater than or equal to 38%, and Ti+Nb being greater than or equal to 16(C+N), less than or equal to 0.005% of O, and the balance Fe and inevitable impurities. The ferritic stainless steel provided by the invention can tolerate the corrosion of various concentration sulfuric acids at a temperature of less than 60 DEG C and at a concentration of less than or equal to 98wt%, also has good impact toughness and welding performance. With a pitting resistance equivalent PREN of greater than or equal to 38, the ferritic stainless steel has corrosion resistance far superior to conventional ferritic stainless steel, and is equivalent to superaustenitic stainless steel and nickel based alloys.

Description

technical field [0001] The invention relates to a sulfuric acid-resistant ferritic stainless steel and a manufacturing method thereof. The ferritic stainless steel can be used in various environments in contact with sulfuric acid, such as towers, tanks, tanks, pipelines and acid Refrigerators and other equipment, as well as sulfur-containing exhaust gas chimneys, flues, and exhaust gas desulfurization devices in petrochemical and other industries. Background technique [0002] Sulfuric acid is widely used in the national economy and is an important raw material for fertilizer industry, chemical fiber industry, nonferrous metallurgy industry and various organic and inorganic chemical industries. Sulfuric acid is a highly corrosive and extremely complex process acid. Therefore, both sulfuric acid manufacturers and users are facing headaches of corrosion. [0003] An important feature of sulfuric acid corrosion is that it is oxidative or reductive depending on the temperature...

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Problems solved by technology

[0012] Chinese patents CN201110134627.2, CN95110069.6 and CN03141708.6 can withstand a certain concentration of sulfuric acid corrosion, but all contain a large amount of precious metal Ni, which belongs to austenitic stainless steel and is expensive;

[0013] Chinese patent 201110300454.7 is a ferritic stainless steel resistant to concentrated sulfuric acid, Nb is mono-stable, without adding Ti, Al, V, Ni and other elements, the impact toughness and weldability are insufficient, and it can only withstand 98% concentrated sulfuric acid, and it is resistant to dilute sulfuric acid. Corrosion in general

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