Ti alloying technology for reducing layering defect of TP321 stainless steel seamless tube

Abstract

The invention relates to the technical field of stainless steel smelting, and provides a Ti alloying technology for reducing the layering defect of a TP321 stainless steel seamless tube. The Ti alloying technology comprises the following steps of providing crude molten steel by an electric arc furnace, carrying out AOD oxygen blowing decarburization, carrying out AOD ferrosilicon reduction, carrying out AOD aluminum deep deoxidation, tapping after AOD first Ti alloying, carrying out LF refining furnace calcium treatment and then carrying out second Ti alloying, taking out of a station after LF refining furnace third Ti alloying, and carrying out die casting. According to the Ti alloying technology, a three-step technology in a titanium alloying process is originally created, the yield of three-step Ti alloying is gradually increased, generation of TiOx inclusions is reduced, the content of large-size inclusions such as SiO2-Al2O3-MnO-CaO and TiOx-MnO in stainless steel is effectively reduced, the layering defect in the stainless steel seamless tube is reduced, and the ultrasonic flaw detection qualification rate of the stainless steel seamless tube is increased.

Description

technical field [0001] The invention relates to the technical field of stainless steel smelting, in particular to a Ti alloying process for reducing delamination defects of TP321 stainless steel seamless pipes. Background technique [0002] Austenitic stainless steel is widely used in petroleum, nuclear industry, transportation, aerospace and other industrial sectors and daily necessities industry due to its excellent corrosion resistance, formability and strength and toughness in a wide temperature range. Its output accounts for about 70% of the total stainless steel. Ti element is widely used in stainless steel, mainly through the precipitation of TiN(C,N) particles of different sizes and uniform distribution to achieve stabilization, pinning and dispersion strengthening, thereby further improving the corrosion resistance and toughness of stainless steel. TP321 is a typical titanium-containing austenitic stainless steel, which has better high-temperature corrosion resista...

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Problems solved by technology

[0006] The purpose of the present invention is to at least overcome one of the deficiencies in the prior art, aiming at the problem of unstable control of delamination defects of TP321 stainless steel seamless pipes at present, a Ti alloying process for reducing delamination defects of TP321 stainless steel seamless pipes is provided, The process route of "electric arc furnace + 20t AOD refining furnace + LF refining furnace + mold casting" is adopted to strictly control the composition and temperature of molten steel entering AOD furnace, and reduce the degree of overoxidation of molten steel during oxygen blowing decarburization; reasonably control Ti alloy During the melting process, the content of Al and Ca elements in molten steel can be reduced to reduce MgO·Al 2 o 3 Inclusion content; optimized Ti alloying, original three-step process, in which the first Ti alloying after deep deoxidation of Al in the AOD refining furnace, part of the Ti element was burned to complete the slagging task of the LF refining furnace, and the LF refining furnace Ca treatment The second Ti alloying prevents the addition of Ti alloy in place to cause uneven Ti element content in molten steel, and reduces Ti element and some Al that did not float up in time 2 o 3 -MgO-CaO oxide reaction, the third Ti alloying before the LF refining furnace exits the station to make the content of Ti element in molten steel meet the target composition, the yield of three-step Ti alloying gradually increases, and reduces TiO x The formation of inclusions effectively reduces the size of SiO in stainless steel 2 -Al 2 o 3 -MnO-CaO and TiO x -The content of MnO inclusions reduces the delamination defects in stainless steel seamless pipes and improves the pass rate of ultrasonic flaw detection of stainless steel seamless pipes

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